[PATCH 0/1] EmbeddedPkg/Library: Add VirtualRealTimeClockLib

[PATCH 0/1] EmbeddedPkg/Library: Add VirtualRealTimeClockLib

[Pete Batard]

This is work, which was requested as part of the Raspberry Pi 3 platform
integration, is designed to remove the need to provide various custom RTC
implementations for platforms that don't have a real RTC.

The library, which is arch-agnostic (through usage of the perf counter) is
designed to emulate as much as it can as of a hardware backed RTC, including
time zones, daylight savings and nanosecond precision.

Note that, since it relies on automatically setting of the epoch value at
compilation-time, it is currently only meant to support gcc based build
environments and relies on UNIX-like shells that provide a 'date' command.
For other environments, the compilation is designed to break in a manner that
will direct the builder to contact the edk2 mailing list, so that we can look
at adding support for their setup.

Regards,

/Pete

Pete Batard (1):
  EmbeddedPkg/Library: Add VirtualRealTimeClockLib

 .../VirtualRealTimeClockLib.c                 | 400 ++++++++++++++++++
 .../VirtualRealTimeClockLib.inf               |  43 ++
 2 files changed, 443 insertions(+)
 create mode 100644 EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
 create mode 100644 EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf

-- 
2.17.0.windows.1

[PATCH 1/1] EmbeddedPkg/Library: Add VirtualRealTimeClockLib

[Pete Batard]

This is designed to be used on platforms where a a real RTC is not
available and relies on an RtcEpochSeconds variable having been set or,
if that is not the case, falls back to using the epoch embedded at
compilation time.

Note that, in order to keep things simple for the setting of the
compilation time variable, only GCC environments with UNIX-like shells
and where a 'date' command is available are meant to be supported for
now.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Pete Batard <pete@akeo.ie>
---
 EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c   | 400 ++++++++++++++++++++
 EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf |  43 +++
 2 files changed, 443 insertions(+)

diff --git a/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
new file mode 100644
index 000000000000..4c354730d02b
--- /dev/null
+++ b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
@@ -0,0 +1,400 @@
+/** @file
+ *
+ *  Implement virtual EFI RealTimeClock runtime services.
+ *
+ *  Coypright (c) 2019, Pete Batard <pete@akeo.ie>
+ *  Copyright (c) 2018, Andrei Warkentin <andrey.warkentin@gmail.com>
+ *  Copyright (c) 2011-2014, ARM Ltd. All rights reserved.
+ *  Copyright (c) 2008-2010, Apple Inc. All rights reserved.
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *
+ *  This program and the accompanying materials
+ *  are licensed and made available under the terms and conditions of the BSD License
+ *  which accompanies this distribution.  The full text of the license may be found at
+ *  http://opensource.org/licenses/bsd-license.php
+ *
+ *  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+ *
+ *  Based on ArmPlatformPkg/Library/PL031RealTimeClockLib/PL031RealTimeClockLib.inf
+ *
+ **/
+
+#include <PiDxe.h>
+#include <Library/BaseLib.h>
+#include <Library/DebugLib.h>
+#include <Library/IoLib.h>
+#include <Library/RealTimeClockLib.h>
+#include <Library/TimerLib.h>
+#include <Library/TimeBaseLib.h>
+#include <Library/UefiRuntimeLib.h>
+
+STATIC CONST CHAR16  mEpochVariableName[]     = L"RtcEpochSeconds";
+STATIC CONST CHAR16  mTimeZoneVariableName[]  = L"RtcTimeZone";
+STATIC CONST CHAR16  mDaylightVariableName[]  = L"RtcDaylight";
+
+/**
+   Returns the current time and date information, and the time-keeping capabilities
+   of the virtual RTC.
+
+   @param  Time                  A pointer to storage to receive a snapshot of the current time.
+   @param  Capabilities          An optional pointer to a buffer to receive the real time clock
+                                 device's capabilities.
+
+   @retval EFI_SUCCESS           The operation completed successfully.
+   @retval EFI_INVALID_PARAMETER Time is NULL.
+   @retval EFI_DEVICE_ERROR      The time could not be retrieved due to hardware error.
+
+**/
+EFI_STATUS
+EFIAPI
+LibGetTime (
+  OUT EFI_TIME               *Time,
+  OUT EFI_TIME_CAPABILITIES  *Capabilities
+  )
+{
+  EFI_STATUS  Status;
+  UINT32      EpochSeconds;
+  INT16       TimeZone;
+  UINT8       Daylight;
+  UINT64      Freq;
+  UINT64      Counter;
+  UINT64      Remainder;
+  UINTN       ElapsedSeconds;
+  UINTN       Size;
+
+  if (Time == NULL) {
+    return EFI_INVALID_PARAMETER;
+  }
+
+  // Get the counter frequency
+  Freq = GetPerformanceCounterProperties (NULL, NULL);
+  if (Freq == 0) {
+    return EFI_DEVICE_ERROR;
+  }
+
+  // Get the epoch time from non-volatile storage
+  Size = sizeof (UINTN);
+  ElapsedSeconds = 0;
+  Status = EfiGetVariable (
+             (CHAR16 *)mEpochVariableName,
+             &gEfiCallerIdGuid,
+             NULL,
+             &Size,
+             (VOID *)&ElapsedSeconds
+             );
+  // Fall back to compilation-time epoch if not set
+  if (EFI_ERROR (Status)) {
+    ASSERT(Status != EFI_INVALID_PARAMETER);
+    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
+    //
+    // The following is intended to produce a compilation error on build
+    // environments where BUILD_EPOCH can not be set from inline shell.
+    // If you are attempting to use this library on such an environment, please
+    // contact the edk2 mailing list, so we can try to add support for it.
+    //
+    ElapsedSeconds = BUILD_EPOCH;
+    DEBUG ((
+      DEBUG_INFO,
+      "LibGetTime: %s non volatile variable was not found - Using compilation time epoch.\n",
+      mEpochVariableName
+      ));
+  }
+  Counter = GetPerformanceCounter ();
+  ElapsedSeconds += DivU64x64Remainder (Counter, Freq, &Remainder);
+
+  // Get the current time zone information from non-volatile storage
+  Size = sizeof (TimeZone);
+  Status = EfiGetVariable (
+             (CHAR16 *)mTimeZoneVariableName,
+             &gEfiCallerIdGuid,
+             NULL,
+             &Size,
+             (VOID *)&TimeZone
+             );
+
+  if (EFI_ERROR (Status)) {
+    ASSERT(Status != EFI_INVALID_PARAMETER);
+    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
+
+    if (Status != EFI_NOT_FOUND) {
+      return Status;
+    }
+
+    // The time zone variable does not exist in non-volatile storage, so create it.
+    Time->TimeZone = EFI_UNSPECIFIED_TIMEZONE;
+    // Store it
+    Status = EfiSetVariable (
+               (CHAR16 *)mTimeZoneVariableName,
+               &gEfiCallerIdGuid,
+               EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
+               Size,
+               (VOID *)&(Time->TimeZone)
+               );
+    if (EFI_ERROR (Status)) {
+      DEBUG ((
+        DEBUG_ERROR,
+        "LibGetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
+        mTimeZoneVariableName,
+        Status
+        ));
+      return Status;
+    }
+  } else {
+    // Got the time zone
+    Time->TimeZone = TimeZone;
+
+    // Check TimeZone bounds: -1440 to 1440 or 2047
+    if (((Time->TimeZone < -1440) || (Time->TimeZone > 1440))
+        && (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE)) {
+      Time->TimeZone = EFI_UNSPECIFIED_TIMEZONE;
+    }
+
+    // Adjust for the correct time zone
+    if (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE) {
+      EpochSeconds += Time->TimeZone * SEC_PER_MIN;
+    }
+  }
+
+  // Get the current daylight information from non-volatile storage
+  Size = sizeof (Daylight);
+  Status = EfiGetVariable (
+             (CHAR16 *)mDaylightVariableName,
+             &gEfiCallerIdGuid,
+             NULL,
+             &Size,
+             (VOID *)&Daylight
+           );
+
+  if (EFI_ERROR (Status)) {
+    ASSERT(Status != EFI_INVALID_PARAMETER);
+    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
+
+    if (Status != EFI_NOT_FOUND) {
+      return Status;
+    }
+
+    // The daylight variable does not exist in non-volatile storage, so create it.
+    Time->Daylight = 0;
+    // Store it
+    Status = EfiSetVariable (
+               (CHAR16 *)mDaylightVariableName,
+               &gEfiCallerIdGuid,
+               EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
+               Size,
+               (VOID *)&(Time->Daylight)
+               );
+    if (EFI_ERROR (Status)) {
+      DEBUG ((
+        DEBUG_ERROR,
+        "LibGetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
+        mDaylightVariableName,
+        Status
+        ));
+      return Status;
+    }
+  } else {
+    // Got the daylight information
+    Time->Daylight = Daylight;
+
+    // Adjust for the correct period
+    if ((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == EFI_TIME_IN_DAYLIGHT) {
+      // Convert to adjusted time, i.e. spring forwards one hour
+      EpochSeconds += SEC_PER_HOUR;
+    }
+  }
+
+  EpochToEfiTime (ElapsedSeconds, Time);
+
+  // Because we use the performance counter, we can fill the Nanosecond attribute
+  // provided that the remainder doesn't overflow 64-bit during multiplication.
+  if (Remainder <= 18446744073U) {
+    Time->Nanosecond = MultU64x64 (Remainder, 1000000000U) / Freq;
+  } else {
+    DEBUG ((DEBUG_WARN, "LibGetTime: Nanosecond value not set (64-bit overflow).\n"));
+  }
+
+  if (Capabilities) {
+    Capabilities->Accuracy   = 0;
+    Capabilities->Resolution = Freq;
+    Capabilities->SetsToZero = FALSE;
+  }
+
+  return EFI_SUCCESS;
+}
+
+/**
+   Sets the current local time and date information.
+
+   @param  Time                  A pointer to the current time.
+
+   @retval EFI_SUCCESS           The operation completed successfully.
+   @retval EFI_INVALID_PARAMETER A time field is out of range.
+   @retval EFI_DEVICE_ERROR      The time could not be set due due to hardware error.
+
+**/
+EFI_STATUS
+EFIAPI
+LibSetTime (
+  IN EFI_TIME  *Time
+  )
+{
+  EFI_STATUS  Status;
+  UINTN       EpochSeconds;
+
+  if (!IsTimeValid (Time)) {
+    return EFI_INVALID_PARAMETER;
+  }
+
+  EpochSeconds = EfiTimeToEpoch (Time);
+
+  // Adjust for the correct time zone, i.e. convert to UTC time zone
+  if (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE) {
+    EpochSeconds -= Time->TimeZone * SEC_PER_MIN;
+  }
+
+  // Adjust for the correct period
+  if ((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == EFI_TIME_IN_DAYLIGHT) {
+    // Convert to un-adjusted time, i.e. fall back one hour
+    EpochSeconds -= SEC_PER_HOUR;
+  }
+
+  // Save the current time zone information into non-volatile storage
+  Status = EfiSetVariable (
+             (CHAR16 *)mTimeZoneVariableName,
+             &gEfiCallerIdGuid,
+             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
+             sizeof (Time->TimeZone),
+             (VOID *)&(Time->TimeZone)
+             );
+  if (EFI_ERROR (Status)) {
+    DEBUG ((
+      DEBUG_ERROR,
+      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
+      mTimeZoneVariableName,
+      Status
+      ));
+    return Status;
+  }
+
+  // Save the current daylight information into non-volatile storage
+  Status = EfiSetVariable (
+             (CHAR16 *)mDaylightVariableName,
+             &gEfiCallerIdGuid,
+             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
+             sizeof(Time->Daylight),
+             (VOID *)&(Time->Daylight)
+           );
+  if (EFI_ERROR (Status)) {
+    DEBUG ((
+      DEBUG_ERROR,
+      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
+      mDaylightVariableName,
+      Status
+      ));
+    return Status;
+  }
+
+  Status = EfiSetVariable (
+             (CHAR16 *)mEpochVariableName,
+             &gEfiCallerIdGuid,
+             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
+             sizeof (EpochSeconds),
+             &EpochSeconds
+             );
+  if (EFI_ERROR (Status)) {
+    DEBUG ((
+      DEBUG_ERROR,
+      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
+      mDaylightVariableName,
+      Status
+      ));
+    return Status;
+  }
+
+  return EFI_SUCCESS;
+}
+
+/**
+   Returns the current wakeup alarm clock setting.
+
+   @param  Enabled               Indicates if the alarm is currently enabled or disabled.
+   @param  Pending               Indicates if the alarm signal is pending and requires acknowledgement.
+   @param  Time                  The current alarm setting.
+
+   @retval EFI_SUCCESS           The alarm settings were returned.
+   @retval EFI_INVALID_PARAMETER Any parameter is NULL.
+   @retval EFI_DEVICE_ERROR      The wakeup time could not be retrieved due to a hardware error.
+
+**/
+EFI_STATUS
+EFIAPI
+LibGetWakeupTime (
+  OUT BOOLEAN   *Enabled,
+  OUT BOOLEAN   *Pending,
+  OUT EFI_TIME  *Time
+  )
+{
+  return EFI_UNSUPPORTED;
+}
+
+/**
+   Sets the system wakeup alarm clock time.
+
+   @param  Enabled               Enable or disable the wakeup alarm.
+   @param  Time                  If Enable is TRUE, the time to set the wakeup alarm for.
+
+   @retval EFI_SUCCESS           If Enable is TRUE, then the wakeup alarm was enabled. If
+   Enable is FALSE, then the wakeup alarm was disabled.
+   @retval EFI_INVALID_PARAMETER A time field is out of range.
+   @retval EFI_DEVICE_ERROR      The wakeup time could not be set due to a hardware error.
+   @retval EFI_UNSUPPORTED       A wakeup timer is not supported on this platform.
+
+**/
+EFI_STATUS
+EFIAPI
+LibSetWakeupTime (
+  IN  BOOLEAN   Enabled,
+  OUT EFI_TIME  *Time
+  )
+{
+  return EFI_UNSUPPORTED;
+}
+
+/**
+   This is the declaration of an EFI image entry point. This can be the entry point to an application
+   written to this specification, an EFI boot service driver, or an EFI runtime driver.
+
+   @param  ImageHandle           Handle that identifies the loaded image.
+   @param  SystemTable           System Table for this image.
+
+   @retval EFI_SUCCESS           The operation completed successfully.
+
+**/
+EFI_STATUS
+EFIAPI
+LibRtcInitialize (
+  IN EFI_HANDLE        ImageHandle,
+  IN EFI_SYSTEM_TABLE  *SystemTable
+  )
+{
+  return EFI_SUCCESS;
+}
+
+/**
+   Fixup internal data so that EFI can be call in virtual mode.
+   Call the passed in Child Notify event and convert any pointers in
+   lib to virtual mode.
+
+   @param[in]    Event   The Event that is being processed
+   @param[in]    Context Event Context
+**/
+VOID
+EFIAPI
+LibRtcVirtualNotifyEvent (
+  IN EFI_EVENT  Event,
+  IN VOID       *Context
+  )
+{
+  return;
+}
diff --git a/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
new file mode 100644
index 000000000000..ed69faad4205
--- /dev/null
+++ b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
@@ -0,0 +1,43 @@
+#/** @file
+#
+#  Implement virtual EFI RealTimeClock runtime services.
+#
+#  Copyright (c) 2019, Pete Batard <pete@akeo.ie>
+#  Copyright (c) 2018, Andrei Warkentin <andrey.warkentin@gmail.com>
+#  Copyright (c) Microsoft Corporation. All rights reserved.
+#
+#  This program and the accompanying materials
+#  are licensed and made available under the terms and conditions of the BSD License
+#  which accompanies this distribution.  The full text of the license may be found at
+#  http://opensource.org/licenses/bsd-license.php
+#
+#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+#
+#**/
+
+[Defines]
+  INF_VERSION                    = 0x0001001A
+  BASE_NAME                      = VirtualRealTimeClockLib
+  FILE_GUID                      = 1E27D461-78F3-4F7D-B1C2-F72384F13A6E
+  MODULE_TYPE                    = BASE
+  VERSION_STRING                 = 1.0
+  LIBRARY_CLASS                  = RealTimeClockLib
+
+[Sources.common]
+  VirtualRealTimeClockLib.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+  EmbeddedPkg/EmbeddedPkg.dec
+
+[LibraryClasses]
+  IoLib
+  DebugLib
+  TimerLib
+  TimeBaseLib
+  UefiRuntimeLib
+
+# Current usage of this library expects GCC in a UNIX-like shell environment with the date command
+[BuildOptions]
+  GCC:*_*_*_CC_FLAGS = -DBUILD_EPOCH=`date +%s`
-- 
2.17.0.windows.1

Re: [PATCH 1/1] EmbeddedPkg/Library: Add VirtualRealTimeClockLib

[Philippe Mathieu-Daudé]

Hi Pete,

On 2/4/19 1:47 PM, Pete Batard wrote:
> This is designed to be used on platforms where a a real RTC is not
> available and relies on an RtcEpochSeconds variable having been set or,
> if that is not the case, falls back to using the epoch embedded at
> compilation time.
> 
> Note that, in order to keep things simple for the setting of the
> compilation time variable, only GCC environments with UNIX-like shells
> and where a 'date' command is available are meant to be supported for
> now.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Pete Batard <pete@akeo.ie>
> ---
>  EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c   | 400 ++++++++++++++++++++
>  EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf |  43 +++
>  2 files changed, 443 insertions(+)
> 
> diff --git a/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
> new file mode 100644
> index 000000000000..4c354730d02b
> --- /dev/null
> +++ b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
> @@ -0,0 +1,400 @@
> +/** @file
> + *
> + *  Implement virtual EFI RealTimeClock runtime services.
> + *
> + *  Coypright (c) 2019, Pete Batard <pete@akeo.ie>
> + *  Copyright (c) 2018, Andrei Warkentin <andrey.warkentin@gmail.com>
> + *  Copyright (c) 2011-2014, ARM Ltd. All rights reserved.
> + *  Copyright (c) 2008-2010, Apple Inc. All rights reserved.
> + *  Copyright (c) Microsoft Corporation. All rights reserved.
> + *
> + *  This program and the accompanying materials
> + *  are licensed and made available under the terms and conditions of the BSD License
> + *  which accompanies this distribution.  The full text of the license may be found at
> + *  http://opensource.org/licenses/bsd-license.php
> + *
> + *  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> + *  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> + *
> + *  Based on ArmPlatformPkg/Library/PL031RealTimeClockLib/PL031RealTimeClockLib.inf
> + *
> + **/
> +
> +#include <PiDxe.h>
> +#include <Library/BaseLib.h>
> +#include <Library/DebugLib.h>
> +#include <Library/IoLib.h>
> +#include <Library/RealTimeClockLib.h>
> +#include <Library/TimerLib.h>
> +#include <Library/TimeBaseLib.h>
> +#include <Library/UefiRuntimeLib.h>
> +
> +STATIC CONST CHAR16  mEpochVariableName[]     = L"RtcEpochSeconds";
> +STATIC CONST CHAR16  mTimeZoneVariableName[]  = L"RtcTimeZone";
> +STATIC CONST CHAR16  mDaylightVariableName[]  = L"RtcDaylight";
> +
> +/**
> +   Returns the current time and date information, and the time-keeping capabilities
> +   of the virtual RTC.
> +
> +   @param  Time                  A pointer to storage to receive a snapshot of the current time.
> +   @param  Capabilities          An optional pointer to a buffer to receive the real time clock
> +                                 device's capabilities.
> +
> +   @retval EFI_SUCCESS           The operation completed successfully.
> +   @retval EFI_INVALID_PARAMETER Time is NULL.
> +   @retval EFI_DEVICE_ERROR      The time could not be retrieved due to hardware error.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +LibGetTime (
> +  OUT EFI_TIME               *Time,
> +  OUT EFI_TIME_CAPABILITIES  *Capabilities
> +  )
> +{
> +  EFI_STATUS  Status;
> +  UINT32      EpochSeconds;
> +  INT16       TimeZone;
> +  UINT8       Daylight;
> +  UINT64      Freq;
> +  UINT64      Counter;
> +  UINT64      Remainder;
> +  UINTN       ElapsedSeconds;
> +  UINTN       Size;
> +
> +  if (Time == NULL) {
> +    return EFI_INVALID_PARAMETER;
> +  }
> +
> +  // Get the counter frequency
> +  Freq = GetPerformanceCounterProperties (NULL, NULL);
> +  if (Freq == 0) {
> +    return EFI_DEVICE_ERROR;
> +  }
> +
> +  // Get the epoch time from non-volatile storage
> +  Size = sizeof (UINTN);
> +  ElapsedSeconds = 0;
> +  Status = EfiGetVariable (
> +             (CHAR16 *)mEpochVariableName,
> +             &gEfiCallerIdGuid,
> +             NULL,
> +             &Size,
> +             (VOID *)&ElapsedSeconds
> +             );
> +  // Fall back to compilation-time epoch if not set
> +  if (EFI_ERROR (Status)) {
> +    ASSERT(Status != EFI_INVALID_PARAMETER);
> +    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
> +    //
> +    // The following is intended to produce a compilation error on build
> +    // environments where BUILD_EPOCH can not be set from inline shell.
> +    // If you are attempting to use this library on such an environment, please
> +    // contact the edk2 mailing list, so we can try to add support for it.
> +    //

What about:

#ifndef BUILD_EPOCH
#define BUILD_EPOCH 1549396000 /* As of this commit */
#endif

> +    ElapsedSeconds = BUILD_EPOCH;
> +    DEBUG ((
> +      DEBUG_INFO,
> +      "LibGetTime: %s non volatile variable was not found - Using compilation time epoch.\n",
> +      mEpochVariableName
> +      ));
> +  }
> +  Counter = GetPerformanceCounter ();
> +  ElapsedSeconds += DivU64x64Remainder (Counter, Freq, &Remainder);
> +
> +  // Get the current time zone information from non-volatile storage
> +  Size = sizeof (TimeZone);
> +  Status = EfiGetVariable (
> +             (CHAR16 *)mTimeZoneVariableName,
> +             &gEfiCallerIdGuid,
> +             NULL,
> +             &Size,
> +             (VOID *)&TimeZone
> +             );
> +
> +  if (EFI_ERROR (Status)) {
> +    ASSERT(Status != EFI_INVALID_PARAMETER);
> +    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
> +
> +    if (Status != EFI_NOT_FOUND) {
> +      return Status;
> +    }
> +
> +    // The time zone variable does not exist in non-volatile storage, so create it.
> +    Time->TimeZone = EFI_UNSPECIFIED_TIMEZONE;
> +    // Store it
> +    Status = EfiSetVariable (
> +               (CHAR16 *)mTimeZoneVariableName,
> +               &gEfiCallerIdGuid,
> +               EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
> +               Size,
> +               (VOID *)&(Time->TimeZone)
> +               );
> +    if (EFI_ERROR (Status)) {
> +      DEBUG ((
> +        DEBUG_ERROR,
> +        "LibGetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
> +        mTimeZoneVariableName,
> +        Status
> +        ));
> +      return Status;
> +    }
> +  } else {
> +    // Got the time zone
> +    Time->TimeZone = TimeZone;
> +
> +    // Check TimeZone bounds: -1440 to 1440 or 2047

Since you use SEC_PER_HOUR, why not add MIN_PER_DAY?

> +    if (((Time->TimeZone < -1440) || (Time->TimeZone > 1440))
> +        && (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE)) {
> +      Time->TimeZone = EFI_UNSPECIFIED_TIMEZONE;
> +    }
> +
> +    // Adjust for the correct time zone
> +    if (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE) {
> +      EpochSeconds += Time->TimeZone * SEC_PER_MIN;
> +    }
> +  }
> +
> +  // Get the current daylight information from non-volatile storage
> +  Size = sizeof (Daylight);
> +  Status = EfiGetVariable (
> +             (CHAR16 *)mDaylightVariableName,
> +             &gEfiCallerIdGuid,
> +             NULL,
> +             &Size,
> +             (VOID *)&Daylight
> +           );
> +
> +  if (EFI_ERROR (Status)) {
> +    ASSERT(Status != EFI_INVALID_PARAMETER);
> +    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
> +
> +    if (Status != EFI_NOT_FOUND) {
> +      return Status;
> +    }
> +
> +    // The daylight variable does not exist in non-volatile storage, so create it.
> +    Time->Daylight = 0;
> +    // Store it
> +    Status = EfiSetVariable (
> +               (CHAR16 *)mDaylightVariableName,
> +               &gEfiCallerIdGuid,
> +               EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
> +               Size,
> +               (VOID *)&(Time->Daylight)
> +               );
> +    if (EFI_ERROR (Status)) {
> +      DEBUG ((
> +        DEBUG_ERROR,
> +        "LibGetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
> +        mDaylightVariableName,
> +        Status
> +        ));
> +      return Status;
> +    }
> +  } else {
> +    // Got the daylight information
> +    Time->Daylight = Daylight;
> +
> +    // Adjust for the correct period
> +    if ((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == EFI_TIME_IN_DAYLIGHT) {
> +      // Convert to adjusted time, i.e. spring forwards one hour
> +      EpochSeconds += SEC_PER_HOUR;
> +    }
> +  }
> +
> +  EpochToEfiTime (ElapsedSeconds, Time);
> +
> +  // Because we use the performance counter, we can fill the Nanosecond attribute
> +  // provided that the remainder doesn't overflow 64-bit during multiplication.
> +  if (Remainder <= 18446744073U) {
> +    Time->Nanosecond = MultU64x64 (Remainder, 1000000000U) / Freq;
> +  } else {
> +    DEBUG ((DEBUG_WARN, "LibGetTime: Nanosecond value not set (64-bit overflow).\n"));
> +  }
> +
> +  if (Capabilities) {
> +    Capabilities->Accuracy   = 0;
> +    Capabilities->Resolution = Freq;
> +    Capabilities->SetsToZero = FALSE;
> +  }
> +
> +  return EFI_SUCCESS;
> +}
> +
> +/**
> +   Sets the current local time and date information.
> +
> +   @param  Time                  A pointer to the current time.
> +
> +   @retval EFI_SUCCESS           The operation completed successfully.
> +   @retval EFI_INVALID_PARAMETER A time field is out of range.
> +   @retval EFI_DEVICE_ERROR      The time could not be set due due to hardware error.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +LibSetTime (
> +  IN EFI_TIME  *Time
> +  )
> +{
> +  EFI_STATUS  Status;
> +  UINTN       EpochSeconds;
> +
> +  if (!IsTimeValid (Time)) {
> +    return EFI_INVALID_PARAMETER;
> +  }
> +
> +  EpochSeconds = EfiTimeToEpoch (Time);
> +
> +  // Adjust for the correct time zone, i.e. convert to UTC time zone
> +  if (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE) {
> +    EpochSeconds -= Time->TimeZone * SEC_PER_MIN;
> +  }
> +
> +  // Adjust for the correct period
> +  if ((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == EFI_TIME_IN_DAYLIGHT) {
> +    // Convert to un-adjusted time, i.e. fall back one hour
> +    EpochSeconds -= SEC_PER_HOUR;
> +  }
> +
> +  // Save the current time zone information into non-volatile storage
> +  Status = EfiSetVariable (
> +             (CHAR16 *)mTimeZoneVariableName,
> +             &gEfiCallerIdGuid,
> +             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
> +             sizeof (Time->TimeZone),
> +             (VOID *)&(Time->TimeZone)
> +             );
> +  if (EFI_ERROR (Status)) {
> +    DEBUG ((
> +      DEBUG_ERROR,
> +      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
> +      mTimeZoneVariableName,
> +      Status
> +      ));
> +    return Status;
> +  }
> +
> +  // Save the current daylight information into non-volatile storage
> +  Status = EfiSetVariable (
> +             (CHAR16 *)mDaylightVariableName,
> +             &gEfiCallerIdGuid,
> +             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
> +             sizeof(Time->Daylight),
> +             (VOID *)&(Time->Daylight)
> +           );
> +  if (EFI_ERROR (Status)) {
> +    DEBUG ((
> +      DEBUG_ERROR,
> +      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
> +      mDaylightVariableName,
> +      Status
> +      ));
> +    return Status;
> +  }
> +
> +  Status = EfiSetVariable (
> +             (CHAR16 *)mEpochVariableName,
> +             &gEfiCallerIdGuid,
> +             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
> +             sizeof (EpochSeconds),
> +             &EpochSeconds
> +             );
> +  if (EFI_ERROR (Status)) {
> +    DEBUG ((
> +      DEBUG_ERROR,
> +      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
> +      mDaylightVariableName,
> +      Status
> +      ));
> +    return Status;
> +  }
> +
> +  return EFI_SUCCESS;
> +}
> +
> +/**
> +   Returns the current wakeup alarm clock setting.
> +
> +   @param  Enabled               Indicates if the alarm is currently enabled or disabled.
> +   @param  Pending               Indicates if the alarm signal is pending and requires acknowledgement.
> +   @param  Time                  The current alarm setting.
> +
> +   @retval EFI_SUCCESS           The alarm settings were returned.
> +   @retval EFI_INVALID_PARAMETER Any parameter is NULL.
> +   @retval EFI_DEVICE_ERROR      The wakeup time could not be retrieved due to a hardware error.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +LibGetWakeupTime (
> +  OUT BOOLEAN   *Enabled,
> +  OUT BOOLEAN   *Pending,
> +  OUT EFI_TIME  *Time
> +  )
> +{
> +  return EFI_UNSUPPORTED;
> +}
> +
> +/**
> +   Sets the system wakeup alarm clock time.
> +
> +   @param  Enabled               Enable or disable the wakeup alarm.
> +   @param  Time                  If Enable is TRUE, the time to set the wakeup alarm for.
> +
> +   @retval EFI_SUCCESS           If Enable is TRUE, then the wakeup alarm was enabled. If
> +   Enable is FALSE, then the wakeup alarm was disabled.
> +   @retval EFI_INVALID_PARAMETER A time field is out of range.
> +   @retval EFI_DEVICE_ERROR      The wakeup time could not be set due to a hardware error.
> +   @retval EFI_UNSUPPORTED       A wakeup timer is not supported on this platform.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +LibSetWakeupTime (
> +  IN  BOOLEAN   Enabled,
> +  OUT EFI_TIME  *Time
> +  )
> +{
> +  return EFI_UNSUPPORTED;
> +}
> +
> +/**
> +   This is the declaration of an EFI image entry point. This can be the entry point to an application
> +   written to this specification, an EFI boot service driver, or an EFI runtime driver.
> +
> +   @param  ImageHandle           Handle that identifies the loaded image.
> +   @param  SystemTable           System Table for this image.
> +
> +   @retval EFI_SUCCESS           The operation completed successfully.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +LibRtcInitialize (
> +  IN EFI_HANDLE        ImageHandle,
> +  IN EFI_SYSTEM_TABLE  *SystemTable
> +  )
> +{
> +  return EFI_SUCCESS;
> +}
> +
> +/**
> +   Fixup internal data so that EFI can be call in virtual mode.
> +   Call the passed in Child Notify event and convert any pointers in
> +   lib to virtual mode.
> +
> +   @param[in]    Event   The Event that is being processed
> +   @param[in]    Context Event Context
> +**/
> +VOID
> +EFIAPI
> +LibRtcVirtualNotifyEvent (
> +  IN EFI_EVENT  Event,
> +  IN VOID       *Context
> +  )
> +{
> +  return;
> +}
> diff --git a/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
> new file mode 100644
> index 000000000000..ed69faad4205
> --- /dev/null
> +++ b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
> @@ -0,0 +1,43 @@
> +#/** @file
> +#
> +#  Implement virtual EFI RealTimeClock runtime services.
> +#
> +#  Copyright (c) 2019, Pete Batard <pete@akeo.ie>
> +#  Copyright (c) 2018, Andrei Warkentin <andrey.warkentin@gmail.com>
> +#  Copyright (c) Microsoft Corporation. All rights reserved.
> +#
> +#  This program and the accompanying materials
> +#  are licensed and made available under the terms and conditions of the BSD License
> +#  which accompanies this distribution.  The full text of the license may be found at
> +#  http://opensource.org/licenses/bsd-license.php
> +#
> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> +#
> +#**/
> +
> +[Defines]
> +  INF_VERSION                    = 0x0001001A
> +  BASE_NAME                      = VirtualRealTimeClockLib
> +  FILE_GUID                      = 1E27D461-78F3-4F7D-B1C2-F72384F13A6E
> +  MODULE_TYPE                    = BASE
> +  VERSION_STRING                 = 1.0
> +  LIBRARY_CLASS                  = RealTimeClockLib
> +
> +[Sources.common]
> +  VirtualRealTimeClockLib.c
> +
> +[Packages]
> +  MdePkg/MdePkg.dec
> +  EmbeddedPkg/EmbeddedPkg.dec
> +
> +[LibraryClasses]
> +  IoLib
> +  DebugLib
> +  TimerLib
> +  TimeBaseLib
> +  UefiRuntimeLib
> +
> +# Current usage of this library expects GCC in a UNIX-like shell environment with the date command
> +[BuildOptions]
> +  GCC:*_*_*_CC_FLAGS = -DBUILD_EPOCH=`date +%s`
> 

Re: [PATCH 1/1] EmbeddedPkg/Library: Add VirtualRealTimeClockLib

[Leif Lindholm]

On Mon, Feb 04, 2019 at 12:47:36PM +0000, Pete Batard wrote:
> This is designed to be used on platforms where a a real RTC is not
> available and relies on an RtcEpochSeconds variable having been set or,
> if that is not the case, falls back to using the epoch embedded at
> compilation time.
> 
> Note that, in order to keep things simple for the setting of the
> compilation time variable, only GCC environments with UNIX-like shells
> and where a 'date' command is available are meant to be supported for
> now.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Pete Batard <pete@akeo.ie>

On the whole, this looks good to me.
One addition we'll need, so that we can build this library standalone
is an entry in EmbeddedPkg.dsc:

diff --git a/EmbeddedPkg/EmbeddedPkg.dsc b/EmbeddedPkg/EmbeddedPkg.dsc
index 4d9e6399d5..dc5040e611 100644
--- a/EmbeddedPkg/EmbeddedPkg.dsc
+++ b/EmbeddedPkg/EmbeddedPkg.dsc
@@ -218,6 +218,7 @@ [Components.common]
   EmbeddedPkg/Library/CoherentDmaLib/CoherentDmaLib.inf
   EmbeddedPkg/Library/NonCoherentDmaLib/NonCoherentDmaLib.inf
   EmbeddedPkg/Library/DxeDtPlatformDtbLoaderLibDefault/DxeDtPlatformDtbLoaderLibDefault.inf
+  EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
   EmbeddedPkg/EmbeddedMonotonicCounter/EmbeddedMonotonicCounter.inf
   EmbeddedPkg/RealTimeClockRuntimeDxe/RealTimeClockRuntimeDxe.inf

I don't have any strong opinions on either of Phil's suggestions, but
if you could give some feedback on those and fold the above in, this
could go in.

Regards,

Leif

> ---
>  EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c   | 400 ++++++++++++++++++++
>  EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf |  43 +++
>  2 files changed, 443 insertions(+)
> 
> diff --git a/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
> new file mode 100644
> index 000000000000..4c354730d02b
> --- /dev/null
> +++ b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
> @@ -0,0 +1,400 @@
> +/** @file
> + *
> + *  Implement virtual EFI RealTimeClock runtime services.
> + *
> + *  Coypright (c) 2019, Pete Batard <pete@akeo.ie>
> + *  Copyright (c) 2018, Andrei Warkentin <andrey.warkentin@gmail.com>
> + *  Copyright (c) 2011-2014, ARM Ltd. All rights reserved.
> + *  Copyright (c) 2008-2010, Apple Inc. All rights reserved.
> + *  Copyright (c) Microsoft Corporation. All rights reserved.
> + *
> + *  This program and the accompanying materials
> + *  are licensed and made available under the terms and conditions of the BSD License
> + *  which accompanies this distribution.  The full text of the license may be found at
> + *  http://opensource.org/licenses/bsd-license.php
> + *
> + *  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> + *  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> + *
> + *  Based on ArmPlatformPkg/Library/PL031RealTimeClockLib/PL031RealTimeClockLib.inf
> + *
> + **/
> +
> +#include <PiDxe.h>
> +#include <Library/BaseLib.h>
> +#include <Library/DebugLib.h>
> +#include <Library/IoLib.h>
> +#include <Library/RealTimeClockLib.h>
> +#include <Library/TimerLib.h>
> +#include <Library/TimeBaseLib.h>
> +#include <Library/UefiRuntimeLib.h>
> +
> +STATIC CONST CHAR16  mEpochVariableName[]     = L"RtcEpochSeconds";
> +STATIC CONST CHAR16  mTimeZoneVariableName[]  = L"RtcTimeZone";
> +STATIC CONST CHAR16  mDaylightVariableName[]  = L"RtcDaylight";
> +
> +/**
> +   Returns the current time and date information, and the time-keeping capabilities
> +   of the virtual RTC.
> +
> +   @param  Time                  A pointer to storage to receive a snapshot of the current time.
> +   @param  Capabilities          An optional pointer to a buffer to receive the real time clock
> +                                 device's capabilities.
> +
> +   @retval EFI_SUCCESS           The operation completed successfully.
> +   @retval EFI_INVALID_PARAMETER Time is NULL.
> +   @retval EFI_DEVICE_ERROR      The time could not be retrieved due to hardware error.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +LibGetTime (
> +  OUT EFI_TIME               *Time,
> +  OUT EFI_TIME_CAPABILITIES  *Capabilities
> +  )
> +{
> +  EFI_STATUS  Status;
> +  UINT32      EpochSeconds;
> +  INT16       TimeZone;
> +  UINT8       Daylight;
> +  UINT64      Freq;
> +  UINT64      Counter;
> +  UINT64      Remainder;
> +  UINTN       ElapsedSeconds;
> +  UINTN       Size;
> +
> +  if (Time == NULL) {
> +    return EFI_INVALID_PARAMETER;
> +  }
> +
> +  // Get the counter frequency
> +  Freq = GetPerformanceCounterProperties (NULL, NULL);
> +  if (Freq == 0) {
> +    return EFI_DEVICE_ERROR;
> +  }
> +
> +  // Get the epoch time from non-volatile storage
> +  Size = sizeof (UINTN);
> +  ElapsedSeconds = 0;
> +  Status = EfiGetVariable (
> +             (CHAR16 *)mEpochVariableName,
> +             &gEfiCallerIdGuid,
> +             NULL,
> +             &Size,
> +             (VOID *)&ElapsedSeconds
> +             );
> +  // Fall back to compilation-time epoch if not set
> +  if (EFI_ERROR (Status)) {
> +    ASSERT(Status != EFI_INVALID_PARAMETER);
> +    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
> +    //
> +    // The following is intended to produce a compilation error on build
> +    // environments where BUILD_EPOCH can not be set from inline shell.
> +    // If you are attempting to use this library on such an environment, please
> +    // contact the edk2 mailing list, so we can try to add support for it.
> +    //
> +    ElapsedSeconds = BUILD_EPOCH;
> +    DEBUG ((
> +      DEBUG_INFO,
> +      "LibGetTime: %s non volatile variable was not found - Using compilation time epoch.\n",
> +      mEpochVariableName
> +      ));
> +  }
> +  Counter = GetPerformanceCounter ();
> +  ElapsedSeconds += DivU64x64Remainder (Counter, Freq, &Remainder);
> +
> +  // Get the current time zone information from non-volatile storage
> +  Size = sizeof (TimeZone);
> +  Status = EfiGetVariable (
> +             (CHAR16 *)mTimeZoneVariableName,
> +             &gEfiCallerIdGuid,
> +             NULL,
> +             &Size,
> +             (VOID *)&TimeZone
> +             );
> +
> +  if (EFI_ERROR (Status)) {
> +    ASSERT(Status != EFI_INVALID_PARAMETER);
> +    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
> +
> +    if (Status != EFI_NOT_FOUND) {
> +      return Status;
> +    }
> +
> +    // The time zone variable does not exist in non-volatile storage, so create it.
> +    Time->TimeZone = EFI_UNSPECIFIED_TIMEZONE;
> +    // Store it
> +    Status = EfiSetVariable (
> +               (CHAR16 *)mTimeZoneVariableName,
> +               &gEfiCallerIdGuid,
> +               EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
> +               Size,
> +               (VOID *)&(Time->TimeZone)
> +               );
> +    if (EFI_ERROR (Status)) {
> +      DEBUG ((
> +        DEBUG_ERROR,
> +        "LibGetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
> +        mTimeZoneVariableName,
> +        Status
> +        ));
> +      return Status;
> +    }
> +  } else {
> +    // Got the time zone
> +    Time->TimeZone = TimeZone;
> +
> +    // Check TimeZone bounds: -1440 to 1440 or 2047
> +    if (((Time->TimeZone < -1440) || (Time->TimeZone > 1440))
> +        && (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE)) {
> +      Time->TimeZone = EFI_UNSPECIFIED_TIMEZONE;
> +    }
> +
> +    // Adjust for the correct time zone
> +    if (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE) {
> +      EpochSeconds += Time->TimeZone * SEC_PER_MIN;
> +    }
> +  }
> +
> +  // Get the current daylight information from non-volatile storage
> +  Size = sizeof (Daylight);
> +  Status = EfiGetVariable (
> +             (CHAR16 *)mDaylightVariableName,
> +             &gEfiCallerIdGuid,
> +             NULL,
> +             &Size,
> +             (VOID *)&Daylight
> +           );
> +
> +  if (EFI_ERROR (Status)) {
> +    ASSERT(Status != EFI_INVALID_PARAMETER);
> +    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
> +
> +    if (Status != EFI_NOT_FOUND) {
> +      return Status;
> +    }
> +
> +    // The daylight variable does not exist in non-volatile storage, so create it.
> +    Time->Daylight = 0;
> +    // Store it
> +    Status = EfiSetVariable (
> +               (CHAR16 *)mDaylightVariableName,
> +               &gEfiCallerIdGuid,
> +               EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
> +               Size,
> +               (VOID *)&(Time->Daylight)
> +               );
> +    if (EFI_ERROR (Status)) {
> +      DEBUG ((
> +        DEBUG_ERROR,
> +        "LibGetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
> +        mDaylightVariableName,
> +        Status
> +        ));
> +      return Status;
> +    }
> +  } else {
> +    // Got the daylight information
> +    Time->Daylight = Daylight;
> +
> +    // Adjust for the correct period
> +    if ((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == EFI_TIME_IN_DAYLIGHT) {
> +      // Convert to adjusted time, i.e. spring forwards one hour
> +      EpochSeconds += SEC_PER_HOUR;
> +    }
> +  }
> +
> +  EpochToEfiTime (ElapsedSeconds, Time);
> +
> +  // Because we use the performance counter, we can fill the Nanosecond attribute
> +  // provided that the remainder doesn't overflow 64-bit during multiplication.
> +  if (Remainder <= 18446744073U) {
> +    Time->Nanosecond = MultU64x64 (Remainder, 1000000000U) / Freq;
> +  } else {
> +    DEBUG ((DEBUG_WARN, "LibGetTime: Nanosecond value not set (64-bit overflow).\n"));
> +  }
> +
> +  if (Capabilities) {
> +    Capabilities->Accuracy   = 0;
> +    Capabilities->Resolution = Freq;
> +    Capabilities->SetsToZero = FALSE;
> +  }
> +
> +  return EFI_SUCCESS;
> +}
> +
> +/**
> +   Sets the current local time and date information.
> +
> +   @param  Time                  A pointer to the current time.
> +
> +   @retval EFI_SUCCESS           The operation completed successfully.
> +   @retval EFI_INVALID_PARAMETER A time field is out of range.
> +   @retval EFI_DEVICE_ERROR      The time could not be set due due to hardware error.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +LibSetTime (
> +  IN EFI_TIME  *Time
> +  )
> +{
> +  EFI_STATUS  Status;
> +  UINTN       EpochSeconds;
> +
> +  if (!IsTimeValid (Time)) {
> +    return EFI_INVALID_PARAMETER;
> +  }
> +
> +  EpochSeconds = EfiTimeToEpoch (Time);
> +
> +  // Adjust for the correct time zone, i.e. convert to UTC time zone
> +  if (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE) {
> +    EpochSeconds -= Time->TimeZone * SEC_PER_MIN;
> +  }
> +
> +  // Adjust for the correct period
> +  if ((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == EFI_TIME_IN_DAYLIGHT) {
> +    // Convert to un-adjusted time, i.e. fall back one hour
> +    EpochSeconds -= SEC_PER_HOUR;
> +  }
> +
> +  // Save the current time zone information into non-volatile storage
> +  Status = EfiSetVariable (
> +             (CHAR16 *)mTimeZoneVariableName,
> +             &gEfiCallerIdGuid,
> +             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
> +             sizeof (Time->TimeZone),
> +             (VOID *)&(Time->TimeZone)
> +             );
> +  if (EFI_ERROR (Status)) {
> +    DEBUG ((
> +      DEBUG_ERROR,
> +      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
> +      mTimeZoneVariableName,
> +      Status
> +      ));
> +    return Status;
> +  }
> +
> +  // Save the current daylight information into non-volatile storage
> +  Status = EfiSetVariable (
> +             (CHAR16 *)mDaylightVariableName,
> +             &gEfiCallerIdGuid,
> +             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
> +             sizeof(Time->Daylight),
> +             (VOID *)&(Time->Daylight)
> +           );
> +  if (EFI_ERROR (Status)) {
> +    DEBUG ((
> +      DEBUG_ERROR,
> +      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
> +      mDaylightVariableName,
> +      Status
> +      ));
> +    return Status;
> +  }
> +
> +  Status = EfiSetVariable (
> +             (CHAR16 *)mEpochVariableName,
> +             &gEfiCallerIdGuid,
> +             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
> +             sizeof (EpochSeconds),
> +             &EpochSeconds
> +             );
> +  if (EFI_ERROR (Status)) {
> +    DEBUG ((
> +      DEBUG_ERROR,
> +      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
> +      mDaylightVariableName,
> +      Status
> +      ));
> +    return Status;
> +  }
> +
> +  return EFI_SUCCESS;
> +}
> +
> +/**
> +   Returns the current wakeup alarm clock setting.
> +
> +   @param  Enabled               Indicates if the alarm is currently enabled or disabled.
> +   @param  Pending               Indicates if the alarm signal is pending and requires acknowledgement.
> +   @param  Time                  The current alarm setting.
> +
> +   @retval EFI_SUCCESS           The alarm settings were returned.
> +   @retval EFI_INVALID_PARAMETER Any parameter is NULL.
> +   @retval EFI_DEVICE_ERROR      The wakeup time could not be retrieved due to a hardware error.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +LibGetWakeupTime (
> +  OUT BOOLEAN   *Enabled,
> +  OUT BOOLEAN   *Pending,
> +  OUT EFI_TIME  *Time
> +  )
> +{
> +  return EFI_UNSUPPORTED;
> +}
> +
> +/**
> +   Sets the system wakeup alarm clock time.
> +
> +   @param  Enabled               Enable or disable the wakeup alarm.
> +   @param  Time                  If Enable is TRUE, the time to set the wakeup alarm for.
> +
> +   @retval EFI_SUCCESS           If Enable is TRUE, then the wakeup alarm was enabled. If
> +   Enable is FALSE, then the wakeup alarm was disabled.
> +   @retval EFI_INVALID_PARAMETER A time field is out of range.
> +   @retval EFI_DEVICE_ERROR      The wakeup time could not be set due to a hardware error.
> +   @retval EFI_UNSUPPORTED       A wakeup timer is not supported on this platform.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +LibSetWakeupTime (
> +  IN  BOOLEAN   Enabled,
> +  OUT EFI_TIME  *Time
> +  )
> +{
> +  return EFI_UNSUPPORTED;
> +}
> +
> +/**
> +   This is the declaration of an EFI image entry point. This can be the entry point to an application
> +   written to this specification, an EFI boot service driver, or an EFI runtime driver.
> +
> +   @param  ImageHandle           Handle that identifies the loaded image.
> +   @param  SystemTable           System Table for this image.
> +
> +   @retval EFI_SUCCESS           The operation completed successfully.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +LibRtcInitialize (
> +  IN EFI_HANDLE        ImageHandle,
> +  IN EFI_SYSTEM_TABLE  *SystemTable
> +  )
> +{
> +  return EFI_SUCCESS;
> +}
> +
> +/**
> +   Fixup internal data so that EFI can be call in virtual mode.
> +   Call the passed in Child Notify event and convert any pointers in
> +   lib to virtual mode.
> +
> +   @param[in]    Event   The Event that is being processed
> +   @param[in]    Context Event Context
> +**/
> +VOID
> +EFIAPI
> +LibRtcVirtualNotifyEvent (
> +  IN EFI_EVENT  Event,
> +  IN VOID       *Context
> +  )
> +{
> +  return;
> +}
> diff --git a/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
> new file mode 100644
> index 000000000000..ed69faad4205
> --- /dev/null
> +++ b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
> @@ -0,0 +1,43 @@
> +#/** @file
> +#
> +#  Implement virtual EFI RealTimeClock runtime services.
> +#
> +#  Copyright (c) 2019, Pete Batard <pete@akeo.ie>
> +#  Copyright (c) 2018, Andrei Warkentin <andrey.warkentin@gmail.com>
> +#  Copyright (c) Microsoft Corporation. All rights reserved.
> +#
> +#  This program and the accompanying materials
> +#  are licensed and made available under the terms and conditions of the BSD License
> +#  which accompanies this distribution.  The full text of the license may be found at
> +#  http://opensource.org/licenses/bsd-license.php
> +#
> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> +#
> +#**/
> +
> +[Defines]
> +  INF_VERSION                    = 0x0001001A
> +  BASE_NAME                      = VirtualRealTimeClockLib
> +  FILE_GUID                      = 1E27D461-78F3-4F7D-B1C2-F72384F13A6E
> +  MODULE_TYPE                    = BASE
> +  VERSION_STRING                 = 1.0
> +  LIBRARY_CLASS                  = RealTimeClockLib
> +
> +[Sources.common]
> +  VirtualRealTimeClockLib.c
> +
> +[Packages]
> +  MdePkg/MdePkg.dec
> +  EmbeddedPkg/EmbeddedPkg.dec
> +
> +[LibraryClasses]
> +  IoLib
> +  DebugLib
> +  TimerLib
> +  TimeBaseLib
> +  UefiRuntimeLib
> +
> +# Current usage of this library expects GCC in a UNIX-like shell environment with the date command
> +[BuildOptions]
> +  GCC:*_*_*_CC_FLAGS = -DBUILD_EPOCH=`date +%s`
> -- 
> 2.17.0.windows.1
> 

Re: [PATCH 1/1] EmbeddedPkg/Library: Add VirtualRealTimeClockLib

[Pete Batard]

Hi Philippe,

Thanks fort reviewing this patch, and apologies for the late reply.

On 2019-02-05 20:57, Philippe Mathieu-Daudé wrote:
> Hi Pete,
> 
> On 2/4/19 1:47 PM, Pete Batard wrote:
>> This is designed to be used on platforms where a a real RTC is not
>> available and relies on an RtcEpochSeconds variable having been set or,
>> if that is not the case, falls back to using the epoch embedded at
>> compilation time.
>>
>> Note that, in order to keep things simple for the setting of the
>> compilation time variable, only GCC environments with UNIX-like shells
>> and where a 'date' command is available are meant to be supported for
>> now.
>>
>> Contributed-under: TianoCore Contribution Agreement 1.1
>> Signed-off-by: Pete Batard <pete@akeo.ie>
>> ---
>>   EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c   | 400 ++++++++++++++++++++
>>   EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf |  43 +++
>>   2 files changed, 443 insertions(+)
>>
>> diff --git a/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
>> new file mode 100644
>> index 000000000000..4c354730d02b
>> --- /dev/null
>> +++ b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
>> @@ -0,0 +1,400 @@
>> +/** @file
>> + *
>> + *  Implement virtual EFI RealTimeClock runtime services.
>> + *
>> + *  Coypright (c) 2019, Pete Batard <pete@akeo.ie>
>> + *  Copyright (c) 2018, Andrei Warkentin <andrey.warkentin@gmail.com>
>> + *  Copyright (c) 2011-2014, ARM Ltd. All rights reserved.
>> + *  Copyright (c) 2008-2010, Apple Inc. All rights reserved.
>> + *  Copyright (c) Microsoft Corporation. All rights reserved.
>> + *
>> + *  This program and the accompanying materials
>> + *  are licensed and made available under the terms and conditions of the BSD License
>> + *  which accompanies this distribution.  The full text of the license may be found at
>> + *  http://opensource.org/licenses/bsd-license.php
>> + *
>> + *  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>> + *  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>> + *
>> + *  Based on ArmPlatformPkg/Library/PL031RealTimeClockLib/PL031RealTimeClockLib.inf
>> + *
>> + **/
>> +
>> +#include <PiDxe.h>
>> +#include <Library/BaseLib.h>
>> +#include <Library/DebugLib.h>
>> +#include <Library/IoLib.h>
>> +#include <Library/RealTimeClockLib.h>
>> +#include <Library/TimerLib.h>
>> +#include <Library/TimeBaseLib.h>
>> +#include <Library/UefiRuntimeLib.h>
>> +
>> +STATIC CONST CHAR16  mEpochVariableName[]     = L"RtcEpochSeconds";
>> +STATIC CONST CHAR16  mTimeZoneVariableName[]  = L"RtcTimeZone";
>> +STATIC CONST CHAR16  mDaylightVariableName[]  = L"RtcDaylight";
>> +
>> +/**
>> +   Returns the current time and date information, and the time-keeping capabilities
>> +   of the virtual RTC.
>> +
>> +   @param  Time                  A pointer to storage to receive a snapshot of the current time.
>> +   @param  Capabilities          An optional pointer to a buffer to receive the real time clock
>> +                                 device's capabilities.
>> +
>> +   @retval EFI_SUCCESS           The operation completed successfully.
>> +   @retval EFI_INVALID_PARAMETER Time is NULL.
>> +   @retval EFI_DEVICE_ERROR      The time could not be retrieved due to hardware error.
>> +
>> +**/
>> +EFI_STATUS
>> +EFIAPI
>> +LibGetTime (
>> +  OUT EFI_TIME               *Time,
>> +  OUT EFI_TIME_CAPABILITIES  *Capabilities
>> +  )
>> +{
>> +  EFI_STATUS  Status;
>> +  UINT32      EpochSeconds;
>> +  INT16       TimeZone;
>> +  UINT8       Daylight;
>> +  UINT64      Freq;
>> +  UINT64      Counter;
>> +  UINT64      Remainder;
>> +  UINTN       ElapsedSeconds;
>> +  UINTN       Size;
>> +
>> +  if (Time == NULL) {
>> +    return EFI_INVALID_PARAMETER;
>> +  }
>> +
>> +  // Get the counter frequency
>> +  Freq = GetPerformanceCounterProperties (NULL, NULL);
>> +  if (Freq == 0) {
>> +    return EFI_DEVICE_ERROR;
>> +  }
>> +
>> +  // Get the epoch time from non-volatile storage
>> +  Size = sizeof (UINTN);
>> +  ElapsedSeconds = 0;
>> +  Status = EfiGetVariable (
>> +             (CHAR16 *)mEpochVariableName,
>> +             &gEfiCallerIdGuid,
>> +             NULL,
>> +             &Size,
>> +             (VOID *)&ElapsedSeconds
>> +             );
>> +  // Fall back to compilation-time epoch if not set
>> +  if (EFI_ERROR (Status)) {
>> +    ASSERT(Status != EFI_INVALID_PARAMETER);
>> +    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
>> +    //
>> +    // The following is intended to produce a compilation error on build
>> +    // environments where BUILD_EPOCH can not be set from inline shell.
>> +    // If you are attempting to use this library on such an environment, please
>> +    // contact the edk2 mailing list, so we can try to add support for it.
>> +    //
> 
> What about:
> 
> #ifndef BUILD_EPOCH
> #define BUILD_EPOCH 1549396000 /* As of this commit */
> #endif

Well, the plan is to see what we can actually do for platforms that 
can't define BUILD_EPOCH to the actual compilation time through shell 
invocation.

Rather than assume that we won't be able to do anything for those, and 
therefore default to an epoch that would have a very large offset even 
when the user went the trouble of recompiling the firmware, I'd rather 
we get a better idea of the environments this might apply to, and see if 
there's anything that could be achieved there.

Of course, if there are other people here that support your suggestion, 
I don't have much of an objection to fall back to a static BUILD_EPOCH 
instead.

>> +    ElapsedSeconds = BUILD_EPOCH;
>> +    DEBUG ((
>> +      DEBUG_INFO,
>> +      "LibGetTime: %s non volatile variable was not found - Using compilation time epoch.\n",
>> +      mEpochVariableName
>> +      ));
>> +  }
>> +  Counter = GetPerformanceCounter ();
>> +  ElapsedSeconds += DivU64x64Remainder (Counter, Freq, &Remainder);
>> +
>> +  // Get the current time zone information from non-volatile storage
>> +  Size = sizeof (TimeZone);
>> +  Status = EfiGetVariable (
>> +             (CHAR16 *)mTimeZoneVariableName,
>> +             &gEfiCallerIdGuid,
>> +             NULL,
>> +             &Size,
>> +             (VOID *)&TimeZone
>> +             );
>> +
>> +  if (EFI_ERROR (Status)) {
>> +    ASSERT(Status != EFI_INVALID_PARAMETER);
>> +    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
>> +
>> +    if (Status != EFI_NOT_FOUND) {
>> +      return Status;
>> +    }
>> +
>> +    // The time zone variable does not exist in non-volatile storage, so create it.
>> +    Time->TimeZone = EFI_UNSPECIFIED_TIMEZONE;
>> +    // Store it
>> +    Status = EfiSetVariable (
>> +               (CHAR16 *)mTimeZoneVariableName,
>> +               &gEfiCallerIdGuid,
>> +               EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
>> +               Size,
>> +               (VOID *)&(Time->TimeZone)
>> +               );
>> +    if (EFI_ERROR (Status)) {
>> +      DEBUG ((
>> +        DEBUG_ERROR,
>> +        "LibGetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
>> +        mTimeZoneVariableName,
>> +        Status
>> +        ));
>> +      return Status;
>> +    }
>> +  } else {
>> +    // Got the time zone
>> +    Time->TimeZone = TimeZone;
>> +
>> +    // Check TimeZone bounds: -1440 to 1440 or 2047
> 
> Since you use SEC_PER_HOUR, why not add MIN_PER_DAY?

Mostly because I copy/pasted this part of the code straight from
ArmPlatformPkg/Library/PL031RealTimeClockLib/ and they don't use that there.

Likewise, if you or someone else feel this is an important change to 
have, I don't mind sending a v2, though it may be a week or two before 
I'm in a position to do that.

Regards,

/Pete

>> +    if (((Time->TimeZone < -1440) || (Time->TimeZone > 1440))
>> +        && (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE)) {
>> +      Time->TimeZone = EFI_UNSPECIFIED_TIMEZONE;
>> +    }
>> +
>> +    // Adjust for the correct time zone
>> +    if (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE) {
>> +      EpochSeconds += Time->TimeZone * SEC_PER_MIN;
>> +    }
>> +  }
>> +
>> +  // Get the current daylight information from non-volatile storage
>> +  Size = sizeof (Daylight);
>> +  Status = EfiGetVariable (
>> +             (CHAR16 *)mDaylightVariableName,
>> +             &gEfiCallerIdGuid,
>> +             NULL,
>> +             &Size,
>> +             (VOID *)&Daylight
>> +           );
>> +
>> +  if (EFI_ERROR (Status)) {
>> +    ASSERT(Status != EFI_INVALID_PARAMETER);
>> +    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
>> +
>> +    if (Status != EFI_NOT_FOUND) {
>> +      return Status;
>> +    }
>> +
>> +    // The daylight variable does not exist in non-volatile storage, so create it.
>> +    Time->Daylight = 0;
>> +    // Store it
>> +    Status = EfiSetVariable (
>> +               (CHAR16 *)mDaylightVariableName,
>> +               &gEfiCallerIdGuid,
>> +               EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
>> +               Size,
>> +               (VOID *)&(Time->Daylight)
>> +               );
>> +    if (EFI_ERROR (Status)) {
>> +      DEBUG ((
>> +        DEBUG_ERROR,
>> +        "LibGetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
>> +        mDaylightVariableName,
>> +        Status
>> +        ));
>> +      return Status;
>> +    }
>> +  } else {
>> +    // Got the daylight information
>> +    Time->Daylight = Daylight;
>> +
>> +    // Adjust for the correct period
>> +    if ((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == EFI_TIME_IN_DAYLIGHT) {
>> +      // Convert to adjusted time, i.e. spring forwards one hour
>> +      EpochSeconds += SEC_PER_HOUR;
>> +    }
>> +  }
>> +
>> +  EpochToEfiTime (ElapsedSeconds, Time);
>> +
>> +  // Because we use the performance counter, we can fill the Nanosecond attribute
>> +  // provided that the remainder doesn't overflow 64-bit during multiplication.
>> +  if (Remainder <= 18446744073U) {
>> +    Time->Nanosecond = MultU64x64 (Remainder, 1000000000U) / Freq;
>> +  } else {
>> +    DEBUG ((DEBUG_WARN, "LibGetTime: Nanosecond value not set (64-bit overflow).\n"));
>> +  }
>> +
>> +  if (Capabilities) {
>> +    Capabilities->Accuracy   = 0;
>> +    Capabilities->Resolution = Freq;
>> +    Capabilities->SetsToZero = FALSE;
>> +  }
>> +
>> +  return EFI_SUCCESS;
>> +}
>> +
>> +/**
>> +   Sets the current local time and date information.
>> +
>> +   @param  Time                  A pointer to the current time.
>> +
>> +   @retval EFI_SUCCESS           The operation completed successfully.
>> +   @retval EFI_INVALID_PARAMETER A time field is out of range.
>> +   @retval EFI_DEVICE_ERROR      The time could not be set due due to hardware error.
>> +
>> +**/
>> +EFI_STATUS
>> +EFIAPI
>> +LibSetTime (
>> +  IN EFI_TIME  *Time
>> +  )
>> +{
>> +  EFI_STATUS  Status;
>> +  UINTN       EpochSeconds;
>> +
>> +  if (!IsTimeValid (Time)) {
>> +    return EFI_INVALID_PARAMETER;
>> +  }
>> +
>> +  EpochSeconds = EfiTimeToEpoch (Time);
>> +
>> +  // Adjust for the correct time zone, i.e. convert to UTC time zone
>> +  if (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE) {
>> +    EpochSeconds -= Time->TimeZone * SEC_PER_MIN;
>> +  }
>> +
>> +  // Adjust for the correct period
>> +  if ((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == EFI_TIME_IN_DAYLIGHT) {
>> +    // Convert to un-adjusted time, i.e. fall back one hour
>> +    EpochSeconds -= SEC_PER_HOUR;
>> +  }
>> +
>> +  // Save the current time zone information into non-volatile storage
>> +  Status = EfiSetVariable (
>> +             (CHAR16 *)mTimeZoneVariableName,
>> +             &gEfiCallerIdGuid,
>> +             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
>> +             sizeof (Time->TimeZone),
>> +             (VOID *)&(Time->TimeZone)
>> +             );
>> +  if (EFI_ERROR (Status)) {
>> +    DEBUG ((
>> +      DEBUG_ERROR,
>> +      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
>> +      mTimeZoneVariableName,
>> +      Status
>> +      ));
>> +    return Status;
>> +  }
>> +
>> +  // Save the current daylight information into non-volatile storage
>> +  Status = EfiSetVariable (
>> +             (CHAR16 *)mDaylightVariableName,
>> +             &gEfiCallerIdGuid,
>> +             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
>> +             sizeof(Time->Daylight),
>> +             (VOID *)&(Time->Daylight)
>> +           );
>> +  if (EFI_ERROR (Status)) {
>> +    DEBUG ((
>> +      DEBUG_ERROR,
>> +      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
>> +      mDaylightVariableName,
>> +      Status
>> +      ));
>> +    return Status;
>> +  }
>> +
>> +  Status = EfiSetVariable (
>> +             (CHAR16 *)mEpochVariableName,
>> +             &gEfiCallerIdGuid,
>> +             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
>> +             sizeof (EpochSeconds),
>> +             &EpochSeconds
>> +             );
>> +  if (EFI_ERROR (Status)) {
>> +    DEBUG ((
>> +      DEBUG_ERROR,
>> +      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
>> +      mDaylightVariableName,
>> +      Status
>> +      ));
>> +    return Status;
>> +  }
>> +
>> +  return EFI_SUCCESS;
>> +}
>> +
>> +/**
>> +   Returns the current wakeup alarm clock setting.
>> +
>> +   @param  Enabled               Indicates if the alarm is currently enabled or disabled.
>> +   @param  Pending               Indicates if the alarm signal is pending and requires acknowledgement.
>> +   @param  Time                  The current alarm setting.
>> +
>> +   @retval EFI_SUCCESS           The alarm settings were returned.
>> +   @retval EFI_INVALID_PARAMETER Any parameter is NULL.
>> +   @retval EFI_DEVICE_ERROR      The wakeup time could not be retrieved due to a hardware error.
>> +
>> +**/
>> +EFI_STATUS
>> +EFIAPI
>> +LibGetWakeupTime (
>> +  OUT BOOLEAN   *Enabled,
>> +  OUT BOOLEAN   *Pending,
>> +  OUT EFI_TIME  *Time
>> +  )
>> +{
>> +  return EFI_UNSUPPORTED;
>> +}
>> +
>> +/**
>> +   Sets the system wakeup alarm clock time.
>> +
>> +   @param  Enabled               Enable or disable the wakeup alarm.
>> +   @param  Time                  If Enable is TRUE, the time to set the wakeup alarm for.
>> +
>> +   @retval EFI_SUCCESS           If Enable is TRUE, then the wakeup alarm was enabled. If
>> +   Enable is FALSE, then the wakeup alarm was disabled.
>> +   @retval EFI_INVALID_PARAMETER A time field is out of range.
>> +   @retval EFI_DEVICE_ERROR      The wakeup time could not be set due to a hardware error.
>> +   @retval EFI_UNSUPPORTED       A wakeup timer is not supported on this platform.
>> +
>> +**/
>> +EFI_STATUS
>> +EFIAPI
>> +LibSetWakeupTime (
>> +  IN  BOOLEAN   Enabled,
>> +  OUT EFI_TIME  *Time
>> +  )
>> +{
>> +  return EFI_UNSUPPORTED;
>> +}
>> +
>> +/**
>> +   This is the declaration of an EFI image entry point. This can be the entry point to an application
>> +   written to this specification, an EFI boot service driver, or an EFI runtime driver.
>> +
>> +   @param  ImageHandle           Handle that identifies the loaded image.
>> +   @param  SystemTable           System Table for this image.
>> +
>> +   @retval EFI_SUCCESS           The operation completed successfully.
>> +
>> +**/
>> +EFI_STATUS
>> +EFIAPI
>> +LibRtcInitialize (
>> +  IN EFI_HANDLE        ImageHandle,
>> +  IN EFI_SYSTEM_TABLE  *SystemTable
>> +  )
>> +{
>> +  return EFI_SUCCESS;
>> +}
>> +
>> +/**
>> +   Fixup internal data so that EFI can be call in virtual mode.
>> +   Call the passed in Child Notify event and convert any pointers in
>> +   lib to virtual mode.
>> +
>> +   @param[in]    Event   The Event that is being processed
>> +   @param[in]    Context Event Context
>> +**/
>> +VOID
>> +EFIAPI
>> +LibRtcVirtualNotifyEvent (
>> +  IN EFI_EVENT  Event,
>> +  IN VOID       *Context
>> +  )
>> +{
>> +  return;
>> +}
>> diff --git a/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
>> new file mode 100644
>> index 000000000000..ed69faad4205
>> --- /dev/null
>> +++ b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
>> @@ -0,0 +1,43 @@
>> +#/** @file
>> +#
>> +#  Implement virtual EFI RealTimeClock runtime services.
>> +#
>> +#  Copyright (c) 2019, Pete Batard <pete@akeo.ie>
>> +#  Copyright (c) 2018, Andrei Warkentin <andrey.warkentin@gmail.com>
>> +#  Copyright (c) Microsoft Corporation. All rights reserved.
>> +#
>> +#  This program and the accompanying materials
>> +#  are licensed and made available under the terms and conditions of the BSD License
>> +#  which accompanies this distribution.  The full text of the license may be found at
>> +#  http://opensource.org/licenses/bsd-license.php
>> +#
>> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>> +#
>> +#**/
>> +
>> +[Defines]
>> +  INF_VERSION                    = 0x0001001A
>> +  BASE_NAME                      = VirtualRealTimeClockLib
>> +  FILE_GUID                      = 1E27D461-78F3-4F7D-B1C2-F72384F13A6E
>> +  MODULE_TYPE                    = BASE
>> +  VERSION_STRING                 = 1.0
>> +  LIBRARY_CLASS                  = RealTimeClockLib
>> +
>> +[Sources.common]
>> +  VirtualRealTimeClockLib.c
>> +
>> +[Packages]
>> +  MdePkg/MdePkg.dec
>> +  EmbeddedPkg/EmbeddedPkg.dec
>> +
>> +[LibraryClasses]
>> +  IoLib
>> +  DebugLib
>> +  TimerLib
>> +  TimeBaseLib
>> +  UefiRuntimeLib
>> +
>> +# Current usage of this library expects GCC in a UNIX-like shell environment with the date command
>> +[BuildOptions]
>> +  GCC:*_*_*_CC_FLAGS = -DBUILD_EPOCH=`date +%s`
>>

Re: [PATCH 1/1] EmbeddedPkg/Library: Add VirtualRealTimeClockLib

[Pete Batard]

Hi Leif,

On 2019-02-12 19:14, Leif Lindholm wrote:
> On Mon, Feb 04, 2019 at 12:47:36PM +0000, Pete Batard wrote:
>> This is designed to be used on platforms where a a real RTC is not
>> available and relies on an RtcEpochSeconds variable having been set or,
>> if that is not the case, falls back to using the epoch embedded at
>> compilation time.
>>
>> Note that, in order to keep things simple for the setting of the
>> compilation time variable, only GCC environments with UNIX-like shells
>> and where a 'date' command is available are meant to be supported for
>> now.
>>
>> Contributed-under: TianoCore Contribution Agreement 1.1
>> Signed-off-by: Pete Batard <pete@akeo.ie>
> 
> On the whole, this looks good to me.

Thanks for the review.

> One addition we'll need, so that we can build this library standalone
> is an entry in EmbeddedPkg.dsc:
> 
> diff --git a/EmbeddedPkg/EmbeddedPkg.dsc b/EmbeddedPkg/EmbeddedPkg.dsc
> index 4d9e6399d5..dc5040e611 100644
> --- a/EmbeddedPkg/EmbeddedPkg.dsc
> +++ b/EmbeddedPkg/EmbeddedPkg.dsc
> @@ -218,6 +218,7 @@ [Components.common]
>     EmbeddedPkg/Library/CoherentDmaLib/CoherentDmaLib.inf
>     EmbeddedPkg/Library/NonCoherentDmaLib/NonCoherentDmaLib.inf
>     EmbeddedPkg/Library/DxeDtPlatformDtbLoaderLibDefault/DxeDtPlatformDtbLoaderLibDefault.inf
> +  EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
>     EmbeddedPkg/EmbeddedMonotonicCounter/EmbeddedMonotonicCounter.inf
>     EmbeddedPkg/RealTimeClockRuntimeDxe/RealTimeClockRuntimeDxe.inf

Well, I actually tried just that but got a build failure when trying to 
compile it (sorry can't remember exactly what was the issue and I don't 
have access to an edk2 test env at the moment) and I saw that some 
libraries in the same location, such as TimeLib which I believe is used 
by some edk2-platforms, are also not referenced at all in the dsc.

So my take was that not all of the libs are required to be included in 
the dsc, especially if they are meant to be referenced directly.

If you feel this is important, I can look into adding the .dsc ref 
again, though provided I can figure out my issue (which may very well 
boil down to me not being too familiar with compiling a standalone 
EmbeddedPkg) it might be a week or two before I can send an updated patch.

Regards,

/Pete

> I don't have any strong opinions on either of Phil's suggestions, but
> if you could give some feedback on those and fold the above in, this
> could go in.
> 
> Regards,
> 
> Leif
> 
>> ---
>>   EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c   | 400 ++++++++++++++++++++
>>   EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf |  43 +++
>>   2 files changed, 443 insertions(+)
>>
>> diff --git a/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
>> new file mode 100644
>> index 000000000000..4c354730d02b
>> --- /dev/null
>> +++ b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
>> @@ -0,0 +1,400 @@
>> +/** @file
>> + *
>> + *  Implement virtual EFI RealTimeClock runtime services.
>> + *
>> + *  Coypright (c) 2019, Pete Batard <pete@akeo.ie>
>> + *  Copyright (c) 2018, Andrei Warkentin <andrey.warkentin@gmail.com>
>> + *  Copyright (c) 2011-2014, ARM Ltd. All rights reserved.
>> + *  Copyright (c) 2008-2010, Apple Inc. All rights reserved.
>> + *  Copyright (c) Microsoft Corporation. All rights reserved.
>> + *
>> + *  This program and the accompanying materials
>> + *  are licensed and made available under the terms and conditions of the BSD License
>> + *  which accompanies this distribution.  The full text of the license may be found at
>> + *  http://opensource.org/licenses/bsd-license.php
>> + *
>> + *  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>> + *  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>> + *
>> + *  Based on ArmPlatformPkg/Library/PL031RealTimeClockLib/PL031RealTimeClockLib.inf
>> + *
>> + **/
>> +
>> +#include <PiDxe.h>
>> +#include <Library/BaseLib.h>
>> +#include <Library/DebugLib.h>
>> +#include <Library/IoLib.h>
>> +#include <Library/RealTimeClockLib.h>
>> +#include <Library/TimerLib.h>
>> +#include <Library/TimeBaseLib.h>
>> +#include <Library/UefiRuntimeLib.h>
>> +
>> +STATIC CONST CHAR16  mEpochVariableName[]     = L"RtcEpochSeconds";
>> +STATIC CONST CHAR16  mTimeZoneVariableName[]  = L"RtcTimeZone";
>> +STATIC CONST CHAR16  mDaylightVariableName[]  = L"RtcDaylight";
>> +
>> +/**
>> +   Returns the current time and date information, and the time-keeping capabilities
>> +   of the virtual RTC.
>> +
>> +   @param  Time                  A pointer to storage to receive a snapshot of the current time.
>> +   @param  Capabilities          An optional pointer to a buffer to receive the real time clock
>> +                                 device's capabilities.
>> +
>> +   @retval EFI_SUCCESS           The operation completed successfully.
>> +   @retval EFI_INVALID_PARAMETER Time is NULL.
>> +   @retval EFI_DEVICE_ERROR      The time could not be retrieved due to hardware error.
>> +
>> +**/
>> +EFI_STATUS
>> +EFIAPI
>> +LibGetTime (
>> +  OUT EFI_TIME               *Time,
>> +  OUT EFI_TIME_CAPABILITIES  *Capabilities
>> +  )
>> +{
>> +  EFI_STATUS  Status;
>> +  UINT32      EpochSeconds;
>> +  INT16       TimeZone;
>> +  UINT8       Daylight;
>> +  UINT64      Freq;
>> +  UINT64      Counter;
>> +  UINT64      Remainder;
>> +  UINTN       ElapsedSeconds;
>> +  UINTN       Size;
>> +
>> +  if (Time == NULL) {
>> +    return EFI_INVALID_PARAMETER;
>> +  }
>> +
>> +  // Get the counter frequency
>> +  Freq = GetPerformanceCounterProperties (NULL, NULL);
>> +  if (Freq == 0) {
>> +    return EFI_DEVICE_ERROR;
>> +  }
>> +
>> +  // Get the epoch time from non-volatile storage
>> +  Size = sizeof (UINTN);
>> +  ElapsedSeconds = 0;
>> +  Status = EfiGetVariable (
>> +             (CHAR16 *)mEpochVariableName,
>> +             &gEfiCallerIdGuid,
>> +             NULL,
>> +             &Size,
>> +             (VOID *)&ElapsedSeconds
>> +             );
>> +  // Fall back to compilation-time epoch if not set
>> +  if (EFI_ERROR (Status)) {
>> +    ASSERT(Status != EFI_INVALID_PARAMETER);
>> +    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
>> +    //
>> +    // The following is intended to produce a compilation error on build
>> +    // environments where BUILD_EPOCH can not be set from inline shell.
>> +    // If you are attempting to use this library on such an environment, please
>> +    // contact the edk2 mailing list, so we can try to add support for it.
>> +    //
>> +    ElapsedSeconds = BUILD_EPOCH;
>> +    DEBUG ((
>> +      DEBUG_INFO,
>> +      "LibGetTime: %s non volatile variable was not found - Using compilation time epoch.\n",
>> +      mEpochVariableName
>> +      ));
>> +  }
>> +  Counter = GetPerformanceCounter ();
>> +  ElapsedSeconds += DivU64x64Remainder (Counter, Freq, &Remainder);
>> +
>> +  // Get the current time zone information from non-volatile storage
>> +  Size = sizeof (TimeZone);
>> +  Status = EfiGetVariable (
>> +             (CHAR16 *)mTimeZoneVariableName,
>> +             &gEfiCallerIdGuid,
>> +             NULL,
>> +             &Size,
>> +             (VOID *)&TimeZone
>> +             );
>> +
>> +  if (EFI_ERROR (Status)) {
>> +    ASSERT(Status != EFI_INVALID_PARAMETER);
>> +    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
>> +
>> +    if (Status != EFI_NOT_FOUND) {
>> +      return Status;
>> +    }
>> +
>> +    // The time zone variable does not exist in non-volatile storage, so create it.
>> +    Time->TimeZone = EFI_UNSPECIFIED_TIMEZONE;
>> +    // Store it
>> +    Status = EfiSetVariable (
>> +               (CHAR16 *)mTimeZoneVariableName,
>> +               &gEfiCallerIdGuid,
>> +               EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
>> +               Size,
>> +               (VOID *)&(Time->TimeZone)
>> +               );
>> +    if (EFI_ERROR (Status)) {
>> +      DEBUG ((
>> +        DEBUG_ERROR,
>> +        "LibGetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
>> +        mTimeZoneVariableName,
>> +        Status
>> +        ));
>> +      return Status;
>> +    }
>> +  } else {
>> +    // Got the time zone
>> +    Time->TimeZone = TimeZone;
>> +
>> +    // Check TimeZone bounds: -1440 to 1440 or 2047
>> +    if (((Time->TimeZone < -1440) || (Time->TimeZone > 1440))
>> +        && (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE)) {
>> +      Time->TimeZone = EFI_UNSPECIFIED_TIMEZONE;
>> +    }
>> +
>> +    // Adjust for the correct time zone
>> +    if (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE) {
>> +      EpochSeconds += Time->TimeZone * SEC_PER_MIN;
>> +    }
>> +  }
>> +
>> +  // Get the current daylight information from non-volatile storage
>> +  Size = sizeof (Daylight);
>> +  Status = EfiGetVariable (
>> +             (CHAR16 *)mDaylightVariableName,
>> +             &gEfiCallerIdGuid,
>> +             NULL,
>> +             &Size,
>> +             (VOID *)&Daylight
>> +           );
>> +
>> +  if (EFI_ERROR (Status)) {
>> +    ASSERT(Status != EFI_INVALID_PARAMETER);
>> +    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
>> +
>> +    if (Status != EFI_NOT_FOUND) {
>> +      return Status;
>> +    }
>> +
>> +    // The daylight variable does not exist in non-volatile storage, so create it.
>> +    Time->Daylight = 0;
>> +    // Store it
>> +    Status = EfiSetVariable (
>> +               (CHAR16 *)mDaylightVariableName,
>> +               &gEfiCallerIdGuid,
>> +               EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
>> +               Size,
>> +               (VOID *)&(Time->Daylight)
>> +               );
>> +    if (EFI_ERROR (Status)) {
>> +      DEBUG ((
>> +        DEBUG_ERROR,
>> +        "LibGetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
>> +        mDaylightVariableName,
>> +        Status
>> +        ));
>> +      return Status;
>> +    }
>> +  } else {
>> +    // Got the daylight information
>> +    Time->Daylight = Daylight;
>> +
>> +    // Adjust for the correct period
>> +    if ((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == EFI_TIME_IN_DAYLIGHT) {
>> +      // Convert to adjusted time, i.e. spring forwards one hour
>> +      EpochSeconds += SEC_PER_HOUR;
>> +    }
>> +  }
>> +
>> +  EpochToEfiTime (ElapsedSeconds, Time);
>> +
>> +  // Because we use the performance counter, we can fill the Nanosecond attribute
>> +  // provided that the remainder doesn't overflow 64-bit during multiplication.
>> +  if (Remainder <= 18446744073U) {
>> +    Time->Nanosecond = MultU64x64 (Remainder, 1000000000U) / Freq;
>> +  } else {
>> +    DEBUG ((DEBUG_WARN, "LibGetTime: Nanosecond value not set (64-bit overflow).\n"));
>> +  }
>> +
>> +  if (Capabilities) {
>> +    Capabilities->Accuracy   = 0;
>> +    Capabilities->Resolution = Freq;
>> +    Capabilities->SetsToZero = FALSE;
>> +  }
>> +
>> +  return EFI_SUCCESS;
>> +}
>> +
>> +/**
>> +   Sets the current local time and date information.
>> +
>> +   @param  Time                  A pointer to the current time.
>> +
>> +   @retval EFI_SUCCESS           The operation completed successfully.
>> +   @retval EFI_INVALID_PARAMETER A time field is out of range.
>> +   @retval EFI_DEVICE_ERROR      The time could not be set due due to hardware error.
>> +
>> +**/
>> +EFI_STATUS
>> +EFIAPI
>> +LibSetTime (
>> +  IN EFI_TIME  *Time
>> +  )
>> +{
>> +  EFI_STATUS  Status;
>> +  UINTN       EpochSeconds;
>> +
>> +  if (!IsTimeValid (Time)) {
>> +    return EFI_INVALID_PARAMETER;
>> +  }
>> +
>> +  EpochSeconds = EfiTimeToEpoch (Time);
>> +
>> +  // Adjust for the correct time zone, i.e. convert to UTC time zone
>> +  if (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE) {
>> +    EpochSeconds -= Time->TimeZone * SEC_PER_MIN;
>> +  }
>> +
>> +  // Adjust for the correct period
>> +  if ((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == EFI_TIME_IN_DAYLIGHT) {
>> +    // Convert to un-adjusted time, i.e. fall back one hour
>> +    EpochSeconds -= SEC_PER_HOUR;
>> +  }
>> +
>> +  // Save the current time zone information into non-volatile storage
>> +  Status = EfiSetVariable (
>> +             (CHAR16 *)mTimeZoneVariableName,
>> +             &gEfiCallerIdGuid,
>> +             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
>> +             sizeof (Time->TimeZone),
>> +             (VOID *)&(Time->TimeZone)
>> +             );
>> +  if (EFI_ERROR (Status)) {
>> +    DEBUG ((
>> +      DEBUG_ERROR,
>> +      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
>> +      mTimeZoneVariableName,
>> +      Status
>> +      ));
>> +    return Status;
>> +  }
>> +
>> +  // Save the current daylight information into non-volatile storage
>> +  Status = EfiSetVariable (
>> +             (CHAR16 *)mDaylightVariableName,
>> +             &gEfiCallerIdGuid,
>> +             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
>> +             sizeof(Time->Daylight),
>> +             (VOID *)&(Time->Daylight)
>> +           );
>> +  if (EFI_ERROR (Status)) {
>> +    DEBUG ((
>> +      DEBUG_ERROR,
>> +      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
>> +      mDaylightVariableName,
>> +      Status
>> +      ));
>> +    return Status;
>> +  }
>> +
>> +  Status = EfiSetVariable (
>> +             (CHAR16 *)mEpochVariableName,
>> +             &gEfiCallerIdGuid,
>> +             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
>> +             sizeof (EpochSeconds),
>> +             &EpochSeconds
>> +             );
>> +  if (EFI_ERROR (Status)) {
>> +    DEBUG ((
>> +      DEBUG_ERROR,
>> +      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
>> +      mDaylightVariableName,
>> +      Status
>> +      ));
>> +    return Status;
>> +  }
>> +
>> +  return EFI_SUCCESS;
>> +}
>> +
>> +/**
>> +   Returns the current wakeup alarm clock setting.
>> +
>> +   @param  Enabled               Indicates if the alarm is currently enabled or disabled.
>> +   @param  Pending               Indicates if the alarm signal is pending and requires acknowledgement.
>> +   @param  Time                  The current alarm setting.
>> +
>> +   @retval EFI_SUCCESS           The alarm settings were returned.
>> +   @retval EFI_INVALID_PARAMETER Any parameter is NULL.
>> +   @retval EFI_DEVICE_ERROR      The wakeup time could not be retrieved due to a hardware error.
>> +
>> +**/
>> +EFI_STATUS
>> +EFIAPI
>> +LibGetWakeupTime (
>> +  OUT BOOLEAN   *Enabled,
>> +  OUT BOOLEAN   *Pending,
>> +  OUT EFI_TIME  *Time
>> +  )
>> +{
>> +  return EFI_UNSUPPORTED;
>> +}
>> +
>> +/**
>> +   Sets the system wakeup alarm clock time.
>> +
>> +   @param  Enabled               Enable or disable the wakeup alarm.
>> +   @param  Time                  If Enable is TRUE, the time to set the wakeup alarm for.
>> +
>> +   @retval EFI_SUCCESS           If Enable is TRUE, then the wakeup alarm was enabled. If
>> +   Enable is FALSE, then the wakeup alarm was disabled.
>> +   @retval EFI_INVALID_PARAMETER A time field is out of range.
>> +   @retval EFI_DEVICE_ERROR      The wakeup time could not be set due to a hardware error.
>> +   @retval EFI_UNSUPPORTED       A wakeup timer is not supported on this platform.
>> +
>> +**/
>> +EFI_STATUS
>> +EFIAPI
>> +LibSetWakeupTime (
>> +  IN  BOOLEAN   Enabled,
>> +  OUT EFI_TIME  *Time
>> +  )
>> +{
>> +  return EFI_UNSUPPORTED;
>> +}
>> +
>> +/**
>> +   This is the declaration of an EFI image entry point. This can be the entry point to an application
>> +   written to this specification, an EFI boot service driver, or an EFI runtime driver.
>> +
>> +   @param  ImageHandle           Handle that identifies the loaded image.
>> +   @param  SystemTable           System Table for this image.
>> +
>> +   @retval EFI_SUCCESS           The operation completed successfully.
>> +
>> +**/
>> +EFI_STATUS
>> +EFIAPI
>> +LibRtcInitialize (
>> +  IN EFI_HANDLE        ImageHandle,
>> +  IN EFI_SYSTEM_TABLE  *SystemTable
>> +  )
>> +{
>> +  return EFI_SUCCESS;
>> +}
>> +
>> +/**
>> +   Fixup internal data so that EFI can be call in virtual mode.
>> +   Call the passed in Child Notify event and convert any pointers in
>> +   lib to virtual mode.
>> +
>> +   @param[in]    Event   The Event that is being processed
>> +   @param[in]    Context Event Context
>> +**/
>> +VOID
>> +EFIAPI
>> +LibRtcVirtualNotifyEvent (
>> +  IN EFI_EVENT  Event,
>> +  IN VOID       *Context
>> +  )
>> +{
>> +  return;
>> +}
>> diff --git a/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
>> new file mode 100644
>> index 000000000000..ed69faad4205
>> --- /dev/null
>> +++ b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
>> @@ -0,0 +1,43 @@
>> +#/** @file
>> +#
>> +#  Implement virtual EFI RealTimeClock runtime services.
>> +#
>> +#  Copyright (c) 2019, Pete Batard <pete@akeo.ie>
>> +#  Copyright (c) 2018, Andrei Warkentin <andrey.warkentin@gmail.com>
>> +#  Copyright (c) Microsoft Corporation. All rights reserved.
>> +#
>> +#  This program and the accompanying materials
>> +#  are licensed and made available under the terms and conditions of the BSD License
>> +#  which accompanies this distribution.  The full text of the license may be found at
>> +#  http://opensource.org/licenses/bsd-license.php
>> +#
>> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>> +#
>> +#**/
>> +
>> +[Defines]
>> +  INF_VERSION                    = 0x0001001A
>> +  BASE_NAME                      = VirtualRealTimeClockLib
>> +  FILE_GUID                      = 1E27D461-78F3-4F7D-B1C2-F72384F13A6E
>> +  MODULE_TYPE                    = BASE
>> +  VERSION_STRING                 = 1.0
>> +  LIBRARY_CLASS                  = RealTimeClockLib
>> +
>> +[Sources.common]
>> +  VirtualRealTimeClockLib.c
>> +
>> +[Packages]
>> +  MdePkg/MdePkg.dec
>> +  EmbeddedPkg/EmbeddedPkg.dec
>> +
>> +[LibraryClasses]
>> +  IoLib
>> +  DebugLib
>> +  TimerLib
>> +  TimeBaseLib
>> +  UefiRuntimeLib
>> +
>> +# Current usage of this library expects GCC in a UNIX-like shell environment with the date command
>> +[BuildOptions]
>> +  GCC:*_*_*_CC_FLAGS = -DBUILD_EPOCH=`date +%s`
>> -- 
>> 2.17.0.windows.1
>>

Re: [PATCH 1/1] EmbeddedPkg/Library: Add VirtualRealTimeClockLib

[Leif Lindholm]

On Fri, Feb 15, 2019 at 01:12:11AM +0100, Pete Batard wrote:
> Hi Leif,
> 
> On 2019-02-12 19:14, Leif Lindholm wrote:
> > On Mon, Feb 04, 2019 at 12:47:36PM +0000, Pete Batard wrote:
> > > This is designed to be used on platforms where a a real RTC is not
> > > available and relies on an RtcEpochSeconds variable having been set or,
> > > if that is not the case, falls back to using the epoch embedded at
> > > compilation time.
> > > 
> > > Note that, in order to keep things simple for the setting of the
> > > compilation time variable, only GCC environments with UNIX-like shells
> > > and where a 'date' command is available are meant to be supported for
> > > now.
> > > 
> > > Contributed-under: TianoCore Contribution Agreement 1.1
> > > Signed-off-by: Pete Batard <pete@akeo.ie>
> > 
> > On the whole, this looks good to me.
> 
> Thanks for the review.
> 
> > One addition we'll need, so that we can build this library standalone
> > is an entry in EmbeddedPkg.dsc:
> > 
> > diff --git a/EmbeddedPkg/EmbeddedPkg.dsc b/EmbeddedPkg/EmbeddedPkg.dsc
> > index 4d9e6399d5..dc5040e611 100644
> > --- a/EmbeddedPkg/EmbeddedPkg.dsc
> > +++ b/EmbeddedPkg/EmbeddedPkg.dsc
> > @@ -218,6 +218,7 @@ [Components.common]
> >     EmbeddedPkg/Library/CoherentDmaLib/CoherentDmaLib.inf
> >     EmbeddedPkg/Library/NonCoherentDmaLib/NonCoherentDmaLib.inf
> >     EmbeddedPkg/Library/DxeDtPlatformDtbLoaderLibDefault/DxeDtPlatformDtbLoaderLibDefault.inf
> > +  EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
> >     EmbeddedPkg/EmbeddedMonotonicCounter/EmbeddedMonotonicCounter.inf
> >     EmbeddedPkg/RealTimeClockRuntimeDxe/RealTimeClockRuntimeDxe.inf
> 
> Well, I actually tried just that but got a build failure when trying to
> compile it (sorry can't remember exactly what was the issue and I don't have
> access to an edk2 test env at the moment) and I saw that some libraries in
> the same location, such as TimeLib which I believe is used by some
> edk2-platforms, are also not referenced at all in the dsc.
> 
> So my take was that not all of the libs are required to be included in the
> dsc, especially if they are meant to be referenced directly.

Oh, we do want all modules in the .dsc - so that we can easily compile
test everything. (And sure, we may have missed some in the past, but
we've gotten better at remembering when we add new ones :)

With the above line added, I built VirtualRealTimeClockLib succesfully
for AARCH64, ARM, IA32 and X64.

> If you feel this is important, I can look into adding the .dsc ref again,
> though provided I can figure out my issue (which may very well boil down to
> me not being too familiar with compiling a standalone EmbeddedPkg) it might
> be a week or two before I can send an updated patch.

All that should be needed is:
build -p EmbeddedPkg/EmbeddedPkg.dsc -m EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf

Regards,

Leif

> Regards,
> 
> /Pete
> 
> > I don't have any strong opinions on either of Phil's suggestions, but
> > if you could give some feedback on those and fold the above in, this
> > could go in.
> > 
> > Regards,
> > 
> > Leif
> > 
> > > ---
> > >   EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c   | 400 ++++++++++++++++++++
> > >   EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf |  43 +++
> > >   2 files changed, 443 insertions(+)
> > > 
> > > diff --git a/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
> > > new file mode 100644
> > > index 000000000000..4c354730d02b
> > > --- /dev/null
> > > +++ b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
> > > @@ -0,0 +1,400 @@
> > > +/** @file
> > > + *
> > > + *  Implement virtual EFI RealTimeClock runtime services.
> > > + *
> > > + *  Coypright (c) 2019, Pete Batard <pete@akeo.ie>
> > > + *  Copyright (c) 2018, Andrei Warkentin <andrey.warkentin@gmail.com>
> > > + *  Copyright (c) 2011-2014, ARM Ltd. All rights reserved.
> > > + *  Copyright (c) 2008-2010, Apple Inc. All rights reserved.
> > > + *  Copyright (c) Microsoft Corporation. All rights reserved.
> > > + *
> > > + *  This program and the accompanying materials
> > > + *  are licensed and made available under the terms and conditions of the BSD License
> > > + *  which accompanies this distribution.  The full text of the license may be found at
> > > + *  http://opensource.org/licenses/bsd-license.php
> > > + *
> > > + *  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> > > + *  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> > > + *
> > > + *  Based on ArmPlatformPkg/Library/PL031RealTimeClockLib/PL031RealTimeClockLib.inf
> > > + *
> > > + **/
> > > +
> > > +#include <PiDxe.h>
> > > +#include <Library/BaseLib.h>
> > > +#include <Library/DebugLib.h>
> > > +#include <Library/IoLib.h>
> > > +#include <Library/RealTimeClockLib.h>
> > > +#include <Library/TimerLib.h>
> > > +#include <Library/TimeBaseLib.h>
> > > +#include <Library/UefiRuntimeLib.h>
> > > +
> > > +STATIC CONST CHAR16  mEpochVariableName[]     = L"RtcEpochSeconds";
> > > +STATIC CONST CHAR16  mTimeZoneVariableName[]  = L"RtcTimeZone";
> > > +STATIC CONST CHAR16  mDaylightVariableName[]  = L"RtcDaylight";
> > > +
> > > +/**
> > > +   Returns the current time and date information, and the time-keeping capabilities
> > > +   of the virtual RTC.
> > > +
> > > +   @param  Time                  A pointer to storage to receive a snapshot of the current time.
> > > +   @param  Capabilities          An optional pointer to a buffer to receive the real time clock
> > > +                                 device's capabilities.
> > > +
> > > +   @retval EFI_SUCCESS           The operation completed successfully.
> > > +   @retval EFI_INVALID_PARAMETER Time is NULL.
> > > +   @retval EFI_DEVICE_ERROR      The time could not be retrieved due to hardware error.
> > > +
> > > +**/
> > > +EFI_STATUS
> > > +EFIAPI
> > > +LibGetTime (
> > > +  OUT EFI_TIME               *Time,
> > > +  OUT EFI_TIME_CAPABILITIES  *Capabilities
> > > +  )
> > > +{
> > > +  EFI_STATUS  Status;
> > > +  UINT32      EpochSeconds;
> > > +  INT16       TimeZone;
> > > +  UINT8       Daylight;
> > > +  UINT64      Freq;
> > > +  UINT64      Counter;
> > > +  UINT64      Remainder;
> > > +  UINTN       ElapsedSeconds;
> > > +  UINTN       Size;
> > > +
> > > +  if (Time == NULL) {
> > > +    return EFI_INVALID_PARAMETER;
> > > +  }
> > > +
> > > +  // Get the counter frequency
> > > +  Freq = GetPerformanceCounterProperties (NULL, NULL);
> > > +  if (Freq == 0) {
> > > +    return EFI_DEVICE_ERROR;
> > > +  }
> > > +
> > > +  // Get the epoch time from non-volatile storage
> > > +  Size = sizeof (UINTN);
> > > +  ElapsedSeconds = 0;
> > > +  Status = EfiGetVariable (
> > > +             (CHAR16 *)mEpochVariableName,
> > > +             &gEfiCallerIdGuid,
> > > +             NULL,
> > > +             &Size,
> > > +             (VOID *)&ElapsedSeconds
> > > +             );
> > > +  // Fall back to compilation-time epoch if not set
> > > +  if (EFI_ERROR (Status)) {
> > > +    ASSERT(Status != EFI_INVALID_PARAMETER);
> > > +    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
> > > +    //
> > > +    // The following is intended to produce a compilation error on build
> > > +    // environments where BUILD_EPOCH can not be set from inline shell.
> > > +    // If you are attempting to use this library on such an environment, please
> > > +    // contact the edk2 mailing list, so we can try to add support for it.
> > > +    //
> > > +    ElapsedSeconds = BUILD_EPOCH;
> > > +    DEBUG ((
> > > +      DEBUG_INFO,
> > > +      "LibGetTime: %s non volatile variable was not found - Using compilation time epoch.\n",
> > > +      mEpochVariableName
> > > +      ));
> > > +  }
> > > +  Counter = GetPerformanceCounter ();
> > > +  ElapsedSeconds += DivU64x64Remainder (Counter, Freq, &Remainder);
> > > +
> > > +  // Get the current time zone information from non-volatile storage
> > > +  Size = sizeof (TimeZone);
> > > +  Status = EfiGetVariable (
> > > +             (CHAR16 *)mTimeZoneVariableName,
> > > +             &gEfiCallerIdGuid,
> > > +             NULL,
> > > +             &Size,
> > > +             (VOID *)&TimeZone
> > > +             );
> > > +
> > > +  if (EFI_ERROR (Status)) {
> > > +    ASSERT(Status != EFI_INVALID_PARAMETER);
> > > +    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
> > > +
> > > +    if (Status != EFI_NOT_FOUND) {
> > > +      return Status;
> > > +    }
> > > +
> > > +    // The time zone variable does not exist in non-volatile storage, so create it.
> > > +    Time->TimeZone = EFI_UNSPECIFIED_TIMEZONE;
> > > +    // Store it
> > > +    Status = EfiSetVariable (
> > > +               (CHAR16 *)mTimeZoneVariableName,
> > > +               &gEfiCallerIdGuid,
> > > +               EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
> > > +               Size,
> > > +               (VOID *)&(Time->TimeZone)
> > > +               );
> > > +    if (EFI_ERROR (Status)) {
> > > +      DEBUG ((
> > > +        DEBUG_ERROR,
> > > +        "LibGetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
> > > +        mTimeZoneVariableName,
> > > +        Status
> > > +        ));
> > > +      return Status;
> > > +    }
> > > +  } else {
> > > +    // Got the time zone
> > > +    Time->TimeZone = TimeZone;
> > > +
> > > +    // Check TimeZone bounds: -1440 to 1440 or 2047
> > > +    if (((Time->TimeZone < -1440) || (Time->TimeZone > 1440))
> > > +        && (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE)) {
> > > +      Time->TimeZone = EFI_UNSPECIFIED_TIMEZONE;
> > > +    }
> > > +
> > > +    // Adjust for the correct time zone
> > > +    if (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE) {
> > > +      EpochSeconds += Time->TimeZone * SEC_PER_MIN;
> > > +    }
> > > +  }
> > > +
> > > +  // Get the current daylight information from non-volatile storage
> > > +  Size = sizeof (Daylight);
> > > +  Status = EfiGetVariable (
> > > +             (CHAR16 *)mDaylightVariableName,
> > > +             &gEfiCallerIdGuid,
> > > +             NULL,
> > > +             &Size,
> > > +             (VOID *)&Daylight
> > > +           );
> > > +
> > > +  if (EFI_ERROR (Status)) {
> > > +    ASSERT(Status != EFI_INVALID_PARAMETER);
> > > +    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
> > > +
> > > +    if (Status != EFI_NOT_FOUND) {
> > > +      return Status;
> > > +    }
> > > +
> > > +    // The daylight variable does not exist in non-volatile storage, so create it.
> > > +    Time->Daylight = 0;
> > > +    // Store it
> > > +    Status = EfiSetVariable (
> > > +               (CHAR16 *)mDaylightVariableName,
> > > +               &gEfiCallerIdGuid,
> > > +               EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
> > > +               Size,
> > > +               (VOID *)&(Time->Daylight)
> > > +               );
> > > +    if (EFI_ERROR (Status)) {
> > > +      DEBUG ((
> > > +        DEBUG_ERROR,
> > > +        "LibGetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
> > > +        mDaylightVariableName,
> > > +        Status
> > > +        ));
> > > +      return Status;
> > > +    }
> > > +  } else {
> > > +    // Got the daylight information
> > > +    Time->Daylight = Daylight;
> > > +
> > > +    // Adjust for the correct period
> > > +    if ((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == EFI_TIME_IN_DAYLIGHT) {
> > > +      // Convert to adjusted time, i.e. spring forwards one hour
> > > +      EpochSeconds += SEC_PER_HOUR;
> > > +    }
> > > +  }
> > > +
> > > +  EpochToEfiTime (ElapsedSeconds, Time);
> > > +
> > > +  // Because we use the performance counter, we can fill the Nanosecond attribute
> > > +  // provided that the remainder doesn't overflow 64-bit during multiplication.
> > > +  if (Remainder <= 18446744073U) {
> > > +    Time->Nanosecond = MultU64x64 (Remainder, 1000000000U) / Freq;
> > > +  } else {
> > > +    DEBUG ((DEBUG_WARN, "LibGetTime: Nanosecond value not set (64-bit overflow).\n"));
> > > +  }
> > > +
> > > +  if (Capabilities) {
> > > +    Capabilities->Accuracy   = 0;
> > > +    Capabilities->Resolution = Freq;
> > > +    Capabilities->SetsToZero = FALSE;
> > > +  }
> > > +
> > > +  return EFI_SUCCESS;
> > > +}
> > > +
> > > +/**
> > > +   Sets the current local time and date information.
> > > +
> > > +   @param  Time                  A pointer to the current time.
> > > +
> > > +   @retval EFI_SUCCESS           The operation completed successfully.
> > > +   @retval EFI_INVALID_PARAMETER A time field is out of range.
> > > +   @retval EFI_DEVICE_ERROR      The time could not be set due due to hardware error.
> > > +
> > > +**/
> > > +EFI_STATUS
> > > +EFIAPI
> > > +LibSetTime (
> > > +  IN EFI_TIME  *Time
> > > +  )
> > > +{
> > > +  EFI_STATUS  Status;
> > > +  UINTN       EpochSeconds;
> > > +
> > > +  if (!IsTimeValid (Time)) {
> > > +    return EFI_INVALID_PARAMETER;
> > > +  }
> > > +
> > > +  EpochSeconds = EfiTimeToEpoch (Time);
> > > +
> > > +  // Adjust for the correct time zone, i.e. convert to UTC time zone
> > > +  if (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE) {
> > > +    EpochSeconds -= Time->TimeZone * SEC_PER_MIN;
> > > +  }
> > > +
> > > +  // Adjust for the correct period
> > > +  if ((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == EFI_TIME_IN_DAYLIGHT) {
> > > +    // Convert to un-adjusted time, i.e. fall back one hour
> > > +    EpochSeconds -= SEC_PER_HOUR;
> > > +  }
> > > +
> > > +  // Save the current time zone information into non-volatile storage
> > > +  Status = EfiSetVariable (
> > > +             (CHAR16 *)mTimeZoneVariableName,
> > > +             &gEfiCallerIdGuid,
> > > +             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
> > > +             sizeof (Time->TimeZone),
> > > +             (VOID *)&(Time->TimeZone)
> > > +             );
> > > +  if (EFI_ERROR (Status)) {
> > > +    DEBUG ((
> > > +      DEBUG_ERROR,
> > > +      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
> > > +      mTimeZoneVariableName,
> > > +      Status
> > > +      ));
> > > +    return Status;
> > > +  }
> > > +
> > > +  // Save the current daylight information into non-volatile storage
> > > +  Status = EfiSetVariable (
> > > +             (CHAR16 *)mDaylightVariableName,
> > > +             &gEfiCallerIdGuid,
> > > +             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
> > > +             sizeof(Time->Daylight),
> > > +             (VOID *)&(Time->Daylight)
> > > +           );
> > > +  if (EFI_ERROR (Status)) {
> > > +    DEBUG ((
> > > +      DEBUG_ERROR,
> > > +      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
> > > +      mDaylightVariableName,
> > > +      Status
> > > +      ));
> > > +    return Status;
> > > +  }
> > > +
> > > +  Status = EfiSetVariable (
> > > +             (CHAR16 *)mEpochVariableName,
> > > +             &gEfiCallerIdGuid,
> > > +             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
> > > +             sizeof (EpochSeconds),
> > > +             &EpochSeconds
> > > +             );
> > > +  if (EFI_ERROR (Status)) {
> > > +    DEBUG ((
> > > +      DEBUG_ERROR,
> > > +      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
> > > +      mDaylightVariableName,
> > > +      Status
> > > +      ));
> > > +    return Status;
> > > +  }
> > > +
> > > +  return EFI_SUCCESS;
> > > +}
> > > +
> > > +/**
> > > +   Returns the current wakeup alarm clock setting.
> > > +
> > > +   @param  Enabled               Indicates if the alarm is currently enabled or disabled.
> > > +   @param  Pending               Indicates if the alarm signal is pending and requires acknowledgement.
> > > +   @param  Time                  The current alarm setting.
> > > +
> > > +   @retval EFI_SUCCESS           The alarm settings were returned.
> > > +   @retval EFI_INVALID_PARAMETER Any parameter is NULL.
> > > +   @retval EFI_DEVICE_ERROR      The wakeup time could not be retrieved due to a hardware error.
> > > +
> > > +**/
> > > +EFI_STATUS
> > > +EFIAPI
> > > +LibGetWakeupTime (
> > > +  OUT BOOLEAN   *Enabled,
> > > +  OUT BOOLEAN   *Pending,
> > > +  OUT EFI_TIME  *Time
> > > +  )
> > > +{
> > > +  return EFI_UNSUPPORTED;
> > > +}
> > > +
> > > +/**
> > > +   Sets the system wakeup alarm clock time.
> > > +
> > > +   @param  Enabled               Enable or disable the wakeup alarm.
> > > +   @param  Time                  If Enable is TRUE, the time to set the wakeup alarm for.
> > > +
> > > +   @retval EFI_SUCCESS           If Enable is TRUE, then the wakeup alarm was enabled. If
> > > +   Enable is FALSE, then the wakeup alarm was disabled.
> > > +   @retval EFI_INVALID_PARAMETER A time field is out of range.
> > > +   @retval EFI_DEVICE_ERROR      The wakeup time could not be set due to a hardware error.
> > > +   @retval EFI_UNSUPPORTED       A wakeup timer is not supported on this platform.
> > > +
> > > +**/
> > > +EFI_STATUS
> > > +EFIAPI
> > > +LibSetWakeupTime (
> > > +  IN  BOOLEAN   Enabled,
> > > +  OUT EFI_TIME  *Time
> > > +  )
> > > +{
> > > +  return EFI_UNSUPPORTED;
> > > +}
> > > +
> > > +/**
> > > +   This is the declaration of an EFI image entry point. This can be the entry point to an application
> > > +   written to this specification, an EFI boot service driver, or an EFI runtime driver.
> > > +
> > > +   @param  ImageHandle           Handle that identifies the loaded image.
> > > +   @param  SystemTable           System Table for this image.
> > > +
> > > +   @retval EFI_SUCCESS           The operation completed successfully.
> > > +
> > > +**/
> > > +EFI_STATUS
> > > +EFIAPI
> > > +LibRtcInitialize (
> > > +  IN EFI_HANDLE        ImageHandle,
> > > +  IN EFI_SYSTEM_TABLE  *SystemTable
> > > +  )
> > > +{
> > > +  return EFI_SUCCESS;
> > > +}
> > > +
> > > +/**
> > > +   Fixup internal data so that EFI can be call in virtual mode.
> > > +   Call the passed in Child Notify event and convert any pointers in
> > > +   lib to virtual mode.
> > > +
> > > +   @param[in]    Event   The Event that is being processed
> > > +   @param[in]    Context Event Context
> > > +**/
> > > +VOID
> > > +EFIAPI
> > > +LibRtcVirtualNotifyEvent (
> > > +  IN EFI_EVENT  Event,
> > > +  IN VOID       *Context
> > > +  )
> > > +{
> > > +  return;
> > > +}
> > > diff --git a/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
> > > new file mode 100644
> > > index 000000000000..ed69faad4205
> > > --- /dev/null
> > > +++ b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
> > > @@ -0,0 +1,43 @@
> > > +#/** @file
> > > +#
> > > +#  Implement virtual EFI RealTimeClock runtime services.
> > > +#
> > > +#  Copyright (c) 2019, Pete Batard <pete@akeo.ie>
> > > +#  Copyright (c) 2018, Andrei Warkentin <andrey.warkentin@gmail.com>
> > > +#  Copyright (c) Microsoft Corporation. All rights reserved.
> > > +#
> > > +#  This program and the accompanying materials
> > > +#  are licensed and made available under the terms and conditions of the BSD License
> > > +#  which accompanies this distribution.  The full text of the license may be found at
> > > +#  http://opensource.org/licenses/bsd-license.php
> > > +#
> > > +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> > > +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> > > +#
> > > +#**/
> > > +
> > > +[Defines]
> > > +  INF_VERSION                    = 0x0001001A
> > > +  BASE_NAME                      = VirtualRealTimeClockLib
> > > +  FILE_GUID                      = 1E27D461-78F3-4F7D-B1C2-F72384F13A6E
> > > +  MODULE_TYPE                    = BASE
> > > +  VERSION_STRING                 = 1.0
> > > +  LIBRARY_CLASS                  = RealTimeClockLib
> > > +
> > > +[Sources.common]
> > > +  VirtualRealTimeClockLib.c
> > > +
> > > +[Packages]
> > > +  MdePkg/MdePkg.dec
> > > +  EmbeddedPkg/EmbeddedPkg.dec
> > > +
> > > +[LibraryClasses]
> > > +  IoLib
> > > +  DebugLib
> > > +  TimerLib
> > > +  TimeBaseLib
> > > +  UefiRuntimeLib
> > > +
> > > +# Current usage of this library expects GCC in a UNIX-like shell environment with the date command
> > > +[BuildOptions]
> > > +  GCC:*_*_*_CC_FLAGS = -DBUILD_EPOCH=`date +%s`
> > > -- 
> > > 2.17.0.windows.1
> > > 
> 

Re: [PATCH 1/1] EmbeddedPkg/Library: Add VirtualRealTimeClockLib

[Ard Biesheuvel]

On Tue, 12 Feb 2019 at 19:14, Leif Lindholm <leif.lindholm@linaro.org> wrote:
>
> On Mon, Feb 04, 2019 at 12:47:36PM +0000, Pete Batard wrote:
> > This is designed to be used on platforms where a a real RTC is not
> > available and relies on an RtcEpochSeconds variable having been set or,
> > if that is not the case, falls back to using the epoch embedded at
> > compilation time.
> >
> > Note that, in order to keep things simple for the setting of the
> > compilation time variable, only GCC environments with UNIX-like shells
> > and where a 'date' command is available are meant to be supported for
> > now.
> >
> > Contributed-under: TianoCore Contribution Agreement 1.1
> > Signed-off-by: Pete Batard <pete@akeo.ie>
>
> On the whole, this looks good to me.
> One addition we'll need, so that we can build this library standalone
> is an entry in EmbeddedPkg.dsc:
>
> diff --git a/EmbeddedPkg/EmbeddedPkg.dsc b/EmbeddedPkg/EmbeddedPkg.dsc
> index 4d9e6399d5..dc5040e611 100644
> --- a/EmbeddedPkg/EmbeddedPkg.dsc
> +++ b/EmbeddedPkg/EmbeddedPkg.dsc
> @@ -218,6 +218,7 @@ [Components.common]
>    EmbeddedPkg/Library/CoherentDmaLib/CoherentDmaLib.inf
>    EmbeddedPkg/Library/NonCoherentDmaLib/NonCoherentDmaLib.inf
>    EmbeddedPkg/Library/DxeDtPlatformDtbLoaderLibDefault/DxeDtPlatformDtbLoaderLibDefault.inf
> +  EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
>    EmbeddedPkg/EmbeddedMonotonicCounter/EmbeddedMonotonicCounter.inf
>    EmbeddedPkg/RealTimeClockRuntimeDxe/RealTimeClockRuntimeDxe.inf
>
> I don't have any strong opinions on either of Phil's suggestions, but
> if you could give some feedback on those and fold the above in, this
> could go in.
>

WIth this addition

Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

Pushed as 1b261a705f94..64a17fadcb79

Re: [PATCH 1/1] EmbeddedPkg/Library: Add VirtualRealTimeClockLib

[Ard Biesheuvel]

On Fri, 15 Feb 2019 at 11:07, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
>
> On Tue, 12 Feb 2019 at 19:14, Leif Lindholm <leif.lindholm@linaro.org> wrote:
> >
> > On Mon, Feb 04, 2019 at 12:47:36PM +0000, Pete Batard wrote:
> > > This is designed to be used on platforms where a a real RTC is not
> > > available and relies on an RtcEpochSeconds variable having been set or,
> > > if that is not the case, falls back to using the epoch embedded at
> > > compilation time.
> > >
> > > Note that, in order to keep things simple for the setting of the
> > > compilation time variable, only GCC environments with UNIX-like shells
> > > and where a 'date' command is available are meant to be supported for
> > > now.
> > >
> > > Contributed-under: TianoCore Contribution Agreement 1.1
> > > Signed-off-by: Pete Batard <pete@akeo.ie>
> >
> > On the whole, this looks good to me.
> > One addition we'll need, so that we can build this library standalone
> > is an entry in EmbeddedPkg.dsc:
> >
> > diff --git a/EmbeddedPkg/EmbeddedPkg.dsc b/EmbeddedPkg/EmbeddedPkg.dsc
> > index 4d9e6399d5..dc5040e611 100644
> > --- a/EmbeddedPkg/EmbeddedPkg.dsc
> > +++ b/EmbeddedPkg/EmbeddedPkg.dsc
> > @@ -218,6 +218,7 @@ [Components.common]
> >    EmbeddedPkg/Library/CoherentDmaLib/CoherentDmaLib.inf
> >    EmbeddedPkg/Library/NonCoherentDmaLib/NonCoherentDmaLib.inf
> >    EmbeddedPkg/Library/DxeDtPlatformDtbLoaderLibDefault/DxeDtPlatformDtbLoaderLibDefault.inf
> > +  EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
> >    EmbeddedPkg/EmbeddedMonotonicCounter/EmbeddedMonotonicCounter.inf
> >    EmbeddedPkg/RealTimeClockRuntimeDxe/RealTimeClockRuntimeDxe.inf
> >
> > I don't have any strong opinions on either of Phil's suggestions, but
> > if you could give some feedback on those and fold the above in, this
> > could go in.
> >
>
> WIth this addition
>
> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>
> Pushed as 1b261a705f94..64a17fadcb79

OK, there is a problem with this code:

+EFI_STATUS
+EFIAPI
+LibGetTime (
+  OUT EFI_TIME               *Time,
+  OUT EFI_TIME_CAPABILITIES  *Capabilities
+  )
+{
+  EFI_STATUS  Status;
+  UINT32      EpochSeconds;

EpochSeconds is declared here, and updated depending on time zone and
DST settings. However, the resulting value is never used anywhere.

It is not clear to me what the correct fix is, so Pete, could you
please look into this?

Re: [PATCH 1/1] EmbeddedPkg/Library: Add VirtualRealTimeClockLib

[Pete Batard]

On 2019-02-15 14:39, Ard Biesheuvel wrote:
> On Fri, 15 Feb 2019 at 11:07, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
>>
>> On Tue, 12 Feb 2019 at 19:14, Leif Lindholm <leif.lindholm@linaro.org> wrote:
>>>
>>> On Mon, Feb 04, 2019 at 12:47:36PM +0000, Pete Batard wrote:
>>>> This is designed to be used on platforms where a a real RTC is not
>>>> available and relies on an RtcEpochSeconds variable having been set or,
>>>> if that is not the case, falls back to using the epoch embedded at
>>>> compilation time.
>>>>
>>>> Note that, in order to keep things simple for the setting of the
>>>> compilation time variable, only GCC environments with UNIX-like shells
>>>> and where a 'date' command is available are meant to be supported for
>>>> now.
>>>>
>>>> Contributed-under: TianoCore Contribution Agreement 1.1
>>>> Signed-off-by: Pete Batard <pete@akeo.ie>
>>>
>>> On the whole, this looks good to me.
>>> One addition we'll need, so that we can build this library standalone
>>> is an entry in EmbeddedPkg.dsc:
>>>
>>> diff --git a/EmbeddedPkg/EmbeddedPkg.dsc b/EmbeddedPkg/EmbeddedPkg.dsc
>>> index 4d9e6399d5..dc5040e611 100644
>>> --- a/EmbeddedPkg/EmbeddedPkg.dsc
>>> +++ b/EmbeddedPkg/EmbeddedPkg.dsc
>>> @@ -218,6 +218,7 @@ [Components.common]
>>>     EmbeddedPkg/Library/CoherentDmaLib/CoherentDmaLib.inf
>>>     EmbeddedPkg/Library/NonCoherentDmaLib/NonCoherentDmaLib.inf
>>>     EmbeddedPkg/Library/DxeDtPlatformDtbLoaderLibDefault/DxeDtPlatformDtbLoaderLibDefault.inf
>>> +  EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
>>>     EmbeddedPkg/EmbeddedMonotonicCounter/EmbeddedMonotonicCounter.inf
>>>     EmbeddedPkg/RealTimeClockRuntimeDxe/RealTimeClockRuntimeDxe.inf
>>>
>>> I don't have any strong opinions on either of Phil's suggestions, but
>>> if you could give some feedback on those and fold the above in, this
>>> could go in.
>>>
>>
>> WIth this addition
>>
>> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>>
>> Pushed as 1b261a705f94..64a17fadcb79
> 
> OK, there is a problem with this code:
> 
> +EFI_STATUS
> +EFIAPI
> +LibGetTime (
> +  OUT EFI_TIME               *Time,
> +  OUT EFI_TIME_CAPABILITIES  *Capabilities
> +  )
> +{
> +  EFI_STATUS  Status;
> +  UINT32      EpochSeconds;
> 
> EpochSeconds is declared here, and updated depending on time zone and
> DST settings. However, the resulting value is never used anywhere.

You're right.

Looks like I forgot to merge all the use of EpochSeconds into 
ElapsedSeconds, from the code I copy/pasted.

I'm very sorry about this, as it's something I should have picked up 
before sending this patch for review.
> It is not clear to me what the correct fix is, so Pete, could you
> please look into this?

I'll send a fix for this as soon as I have a chance. Thanks for pointing 
the mistake.

Regards,

/Pete

Re: [PATCH 1/1] EmbeddedPkg/Library: Add VirtualRealTimeClockLib

[Ard Biesheuvel]

On Fri, 15 Feb 2019 at 15:57, Pete Batard <pete@akeo.ie> wrote:
>
> On 2019-02-15 14:39, Ard Biesheuvel wrote:
> > On Fri, 15 Feb 2019 at 11:07, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
> >>
> >> On Tue, 12 Feb 2019 at 19:14, Leif Lindholm <leif.lindholm@linaro.org> wrote:
> >>>
> >>> On Mon, Feb 04, 2019 at 12:47:36PM +0000, Pete Batard wrote:
> >>>> This is designed to be used on platforms where a a real RTC is not
> >>>> available and relies on an RtcEpochSeconds variable having been set or,
> >>>> if that is not the case, falls back to using the epoch embedded at
> >>>> compilation time.
> >>>>
> >>>> Note that, in order to keep things simple for the setting of the
> >>>> compilation time variable, only GCC environments with UNIX-like shells
> >>>> and where a 'date' command is available are meant to be supported for
> >>>> now.
> >>>>
> >>>> Contributed-under: TianoCore Contribution Agreement 1.1
> >>>> Signed-off-by: Pete Batard <pete@akeo.ie>
> >>>
> >>> On the whole, this looks good to me.
> >>> One addition we'll need, so that we can build this library standalone
> >>> is an entry in EmbeddedPkg.dsc:
> >>>
> >>> diff --git a/EmbeddedPkg/EmbeddedPkg.dsc b/EmbeddedPkg/EmbeddedPkg.dsc
> >>> index 4d9e6399d5..dc5040e611 100644
> >>> --- a/EmbeddedPkg/EmbeddedPkg.dsc
> >>> +++ b/EmbeddedPkg/EmbeddedPkg.dsc
> >>> @@ -218,6 +218,7 @@ [Components.common]
> >>>     EmbeddedPkg/Library/CoherentDmaLib/CoherentDmaLib.inf
> >>>     EmbeddedPkg/Library/NonCoherentDmaLib/NonCoherentDmaLib.inf
> >>>     EmbeddedPkg/Library/DxeDtPlatformDtbLoaderLibDefault/DxeDtPlatformDtbLoaderLibDefault.inf
> >>> +  EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
> >>>     EmbeddedPkg/EmbeddedMonotonicCounter/EmbeddedMonotonicCounter.inf
> >>>     EmbeddedPkg/RealTimeClockRuntimeDxe/RealTimeClockRuntimeDxe.inf
> >>>
> >>> I don't have any strong opinions on either of Phil's suggestions, but
> >>> if you could give some feedback on those and fold the above in, this
> >>> could go in.
> >>>
> >>
> >> WIth this addition
> >>
> >> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> >>
> >> Pushed as 1b261a705f94..64a17fadcb79
> >
> > OK, there is a problem with this code:
> >
> > +EFI_STATUS
> > +EFIAPI
> > +LibGetTime (
> > +  OUT EFI_TIME               *Time,
> > +  OUT EFI_TIME_CAPABILITIES  *Capabilities
> > +  )
> > +{
> > +  EFI_STATUS  Status;
> > +  UINT32      EpochSeconds;
> >
> > EpochSeconds is declared here, and updated depending on time zone and
> > DST settings. However, the resulting value is never used anywhere.
>
> You're right.
>
> Looks like I forgot to merge all the use of EpochSeconds into
> ElapsedSeconds, from the code I copy/pasted.
>
> I'm very sorry about this, as it's something I should have picked up
> before sending this patch for review.

No need to worry about it, as long as you get it fixed :-)

> > It is not clear to me what the correct fix is, so Pete, could you
> > please look into this?
>
> I'll send a fix for this as soon as I have a chance. Thanks for pointing
> the mistake.
>

Re: [PATCH 1/1] EmbeddedPkg/Library: Add VirtualRealTimeClockLib

[Ard Biesheuvel]

On Fri, 15 Feb 2019 at 15:57, Pete Batard <pete@akeo.ie> wrote:
>
> On 2019-02-15 14:39, Ard Biesheuvel wrote:
> > On Fri, 15 Feb 2019 at 11:07, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
> >>
> >> On Tue, 12 Feb 2019 at 19:14, Leif Lindholm <leif.lindholm@linaro.org> wrote:
> >>>
> >>> On Mon, Feb 04, 2019 at 12:47:36PM +0000, Pete Batard wrote:
> >>>> This is designed to be used on platforms where a a real RTC is not
> >>>> available and relies on an RtcEpochSeconds variable having been set or,
> >>>> if that is not the case, falls back to using the epoch embedded at
> >>>> compilation time.
> >>>>
> >>>> Note that, in order to keep things simple for the setting of the
> >>>> compilation time variable, only GCC environments with UNIX-like shells
> >>>> and where a 'date' command is available are meant to be supported for
> >>>> now.
> >>>>
> >>>> Contributed-under: TianoCore Contribution Agreement 1.1
> >>>> Signed-off-by: Pete Batard <pete@akeo.ie>
> >>>
> >>> On the whole, this looks good to me.
> >>> One addition we'll need, so that we can build this library standalone
> >>> is an entry in EmbeddedPkg.dsc:
> >>>
> >>> diff --git a/EmbeddedPkg/EmbeddedPkg.dsc b/EmbeddedPkg/EmbeddedPkg.dsc
> >>> index 4d9e6399d5..dc5040e611 100644
> >>> --- a/EmbeddedPkg/EmbeddedPkg.dsc
> >>> +++ b/EmbeddedPkg/EmbeddedPkg.dsc
> >>> @@ -218,6 +218,7 @@ [Components.common]
> >>>     EmbeddedPkg/Library/CoherentDmaLib/CoherentDmaLib.inf
> >>>     EmbeddedPkg/Library/NonCoherentDmaLib/NonCoherentDmaLib.inf
> >>>     EmbeddedPkg/Library/DxeDtPlatformDtbLoaderLibDefault/DxeDtPlatformDtbLoaderLibDefault.inf
> >>> +  EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
> >>>     EmbeddedPkg/EmbeddedMonotonicCounter/EmbeddedMonotonicCounter.inf
> >>>     EmbeddedPkg/RealTimeClockRuntimeDxe/RealTimeClockRuntimeDxe.inf
> >>>
> >>> I don't have any strong opinions on either of Phil's suggestions, but
> >>> if you could give some feedback on those and fold the above in, this
> >>> could go in.
> >>>
> >>
> >> WIth this addition
> >>
> >> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> >>
> >> Pushed as 1b261a705f94..64a17fadcb79
> >
> > OK, there is a problem with this code:
> >
> > +EFI_STATUS
> > +EFIAPI
> > +LibGetTime (
> > +  OUT EFI_TIME               *Time,
> > +  OUT EFI_TIME_CAPABILITIES  *Capabilities
> > +  )
> > +{
> > +  EFI_STATUS  Status;
> > +  UINT32      EpochSeconds;
> >
> > EpochSeconds is declared here, and updated depending on time zone and
> > DST settings. However, the resulting value is never used anywhere.
>
> You're right.
>
> Looks like I forgot to merge all the use of EpochSeconds into
> ElapsedSeconds, from the code I copy/pasted.
>
> I'm very sorry about this, as it's something I should have picked up
> before sending this patch for review.
> > It is not clear to me what the correct fix is, so Pete, could you
> > please look into this?
>
> I'll send a fix for this as soon as I have a chance. Thanks for pointing
> the mistake.
>

Any progress here?

Re: [edk2] [PATCH 1/1] EmbeddedPkg/Library: Add VirtualRealTimeClockLib

[Philippe Mathieu-Daudé]

Hi Pete,

On 2/4/19 1:47 PM, Pete Batard wrote:
> This is designed to be used on platforms where a a real RTC is not
> available and relies on an RtcEpochSeconds variable having been set or,
> if that is not the case, falls back to using the epoch embedded at
> compilation time.
> 
> Note that, in order to keep things simple for the setting of the
> compilation time variable, only GCC environments with UNIX-like shells
> and where a 'date' command is available are meant to be supported for
> now.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Pete Batard <pete@akeo.ie>
> ---
>   EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c   | 400 ++++++++++++++++++++
>   EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf |  43 +++
>   2 files changed, 443 insertions(+)
> 
> diff --git a/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
> new file mode 100644
> index 000000000000..4c354730d02b
> --- /dev/null
> +++ b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
> @@ -0,0 +1,400 @@
> +/** @file
> + *
> + *  Implement virtual EFI RealTimeClock runtime services.
> + *
> + *  Coypright (c) 2019, Pete Batard <pete@akeo.ie>
> + *  Copyright (c) 2018, Andrei Warkentin <andrey.warkentin@gmail.com>
> + *  Copyright (c) 2011-2014, ARM Ltd. All rights reserved.
> + *  Copyright (c) 2008-2010, Apple Inc. All rights reserved.
> + *  Copyright (c) Microsoft Corporation. All rights reserved.

You forgot the year, it should be 2019 right?
Another occurrence below.

> + *
> + *  This program and the accompanying materials
> + *  are licensed and made available under the terms and conditions of the BSD License
> + *  which accompanies this distribution.  The full text of the license may be found at
> + *  http://opensource.org/licenses/bsd-license.php
> + *
> + *  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> + *  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> + *
> + *  Based on ArmPlatformPkg/Library/PL031RealTimeClockLib/PL031RealTimeClockLib.inf
> + *
> + **/
> +
> +#include <PiDxe.h>
> +#include <Library/BaseLib.h>
> +#include <Library/DebugLib.h>
> +#include <Library/IoLib.h>
> +#include <Library/RealTimeClockLib.h>
> +#include <Library/TimerLib.h>
> +#include <Library/TimeBaseLib.h>
> +#include <Library/UefiRuntimeLib.h>
> +
> +STATIC CONST CHAR16  mEpochVariableName[]     = L"RtcEpochSeconds";
> +STATIC CONST CHAR16  mTimeZoneVariableName[]  = L"RtcTimeZone";
> +STATIC CONST CHAR16  mDaylightVariableName[]  = L"RtcDaylight";
> +
> +/**
> +   Returns the current time and date information, and the time-keeping capabilities
> +   of the virtual RTC.
> +
> +   @param  Time                  A pointer to storage to receive a snapshot of the current time.
> +   @param  Capabilities          An optional pointer to a buffer to receive the real time clock
> +                                 device's capabilities.
> +
> +   @retval EFI_SUCCESS           The operation completed successfully.
> +   @retval EFI_INVALID_PARAMETER Time is NULL.
> +   @retval EFI_DEVICE_ERROR      The time could not be retrieved due to hardware error.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +LibGetTime (
> +  OUT EFI_TIME               *Time,
> +  OUT EFI_TIME_CAPABILITIES  *Capabilities
> +  )
> +{
> +  EFI_STATUS  Status;
> +  UINT32      EpochSeconds;
> +  INT16       TimeZone;
> +  UINT8       Daylight;
> +  UINT64      Freq;
> +  UINT64      Counter;
> +  UINT64      Remainder;
> +  UINTN       ElapsedSeconds;
> +  UINTN       Size;
> +
> +  if (Time == NULL) {
> +    return EFI_INVALID_PARAMETER;
> +  }
> +
> +  // Get the counter frequency
> +  Freq = GetPerformanceCounterProperties (NULL, NULL);
> +  if (Freq == 0) {
> +    return EFI_DEVICE_ERROR;
> +  }
> +
> +  // Get the epoch time from non-volatile storage
> +  Size = sizeof (UINTN);
> +  ElapsedSeconds = 0;
> +  Status = EfiGetVariable (
> +             (CHAR16 *)mEpochVariableName,
> +             &gEfiCallerIdGuid,
> +             NULL,
> +             &Size,
> +             (VOID *)&ElapsedSeconds
> +             );
> +  // Fall back to compilation-time epoch if not set
> +  if (EFI_ERROR (Status)) {
> +    ASSERT(Status != EFI_INVALID_PARAMETER);
> +    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
> +    //
> +    // The following is intended to produce a compilation error on build
> +    // environments where BUILD_EPOCH can not be set from inline shell.
> +    // If you are attempting to use this library on such an environment, please
> +    // contact the edk2 mailing list, so we can try to add support for it.
> +    //
> +    ElapsedSeconds = BUILD_EPOCH;
> +    DEBUG ((
> +      DEBUG_INFO,
> +      "LibGetTime: %s non volatile variable was not found - Using compilation time epoch.\n",
> +      mEpochVariableName
> +      ));
> +  }
> +  Counter = GetPerformanceCounter ();
> +  ElapsedSeconds += DivU64x64Remainder (Counter, Freq, &Remainder);
> +
> +  // Get the current time zone information from non-volatile storage
> +  Size = sizeof (TimeZone);
> +  Status = EfiGetVariable (
> +             (CHAR16 *)mTimeZoneVariableName,
> +             &gEfiCallerIdGuid,
> +             NULL,
> +             &Size,
> +             (VOID *)&TimeZone
> +             );
> +
> +  if (EFI_ERROR (Status)) {
> +    ASSERT(Status != EFI_INVALID_PARAMETER);
> +    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
> +
> +    if (Status != EFI_NOT_FOUND) {
> +      return Status;
> +    }
> +
> +    // The time zone variable does not exist in non-volatile storage, so create it.
> +    Time->TimeZone = EFI_UNSPECIFIED_TIMEZONE;
> +    // Store it
> +    Status = EfiSetVariable (
> +               (CHAR16 *)mTimeZoneVariableName,
> +               &gEfiCallerIdGuid,
> +               EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
> +               Size,
> +               (VOID *)&(Time->TimeZone)
> +               );
> +    if (EFI_ERROR (Status)) {
> +      DEBUG ((
> +        DEBUG_ERROR,
> +        "LibGetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
> +        mTimeZoneVariableName,
> +        Status
> +        ));
> +      return Status;
> +    }
> +  } else {
> +    // Got the time zone
> +    Time->TimeZone = TimeZone;
> +
> +    // Check TimeZone bounds: -1440 to 1440 or 2047
> +    if (((Time->TimeZone < -1440) || (Time->TimeZone > 1440))
> +        && (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE)) {
> +      Time->TimeZone = EFI_UNSPECIFIED_TIMEZONE;
> +    }
> +
> +    // Adjust for the correct time zone
> +    if (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE) {
> +      EpochSeconds += Time->TimeZone * SEC_PER_MIN;
> +    }
> +  }
> +
> +  // Get the current daylight information from non-volatile storage
> +  Size = sizeof (Daylight);
> +  Status = EfiGetVariable (
> +             (CHAR16 *)mDaylightVariableName,
> +             &gEfiCallerIdGuid,
> +             NULL,
> +             &Size,
> +             (VOID *)&Daylight
> +           );
> +
> +  if (EFI_ERROR (Status)) {
> +    ASSERT(Status != EFI_INVALID_PARAMETER);
> +    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
> +
> +    if (Status != EFI_NOT_FOUND) {
> +      return Status;
> +    }
> +
> +    // The daylight variable does not exist in non-volatile storage, so create it.
> +    Time->Daylight = 0;
> +    // Store it
> +    Status = EfiSetVariable (
> +               (CHAR16 *)mDaylightVariableName,
> +               &gEfiCallerIdGuid,
> +               EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
> +               Size,
> +               (VOID *)&(Time->Daylight)
> +               );
> +    if (EFI_ERROR (Status)) {
> +      DEBUG ((
> +        DEBUG_ERROR,
> +        "LibGetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
> +        mDaylightVariableName,
> +        Status
> +        ));
> +      return Status;
> +    }
> +  } else {
> +    // Got the daylight information
> +    Time->Daylight = Daylight;
> +
> +    // Adjust for the correct period
> +    if ((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == EFI_TIME_IN_DAYLIGHT) {
> +      // Convert to adjusted time, i.e. spring forwards one hour
> +      EpochSeconds += SEC_PER_HOUR;
> +    }
> +  }
> +
> +  EpochToEfiTime (ElapsedSeconds, Time);
> +
> +  // Because we use the performance counter, we can fill the Nanosecond attribute
> +  // provided that the remainder doesn't overflow 64-bit during multiplication.
> +  if (Remainder <= 18446744073U) {
> +    Time->Nanosecond = MultU64x64 (Remainder, 1000000000U) / Freq;
> +  } else {
> +    DEBUG ((DEBUG_WARN, "LibGetTime: Nanosecond value not set (64-bit overflow).\n"));
> +  }
> +
> +  if (Capabilities) {
> +    Capabilities->Accuracy   = 0;
> +    Capabilities->Resolution = Freq;
> +    Capabilities->SetsToZero = FALSE;
> +  }
> +
> +  return EFI_SUCCESS;
> +}
> +
> +/**
> +   Sets the current local time and date information.
> +
> +   @param  Time                  A pointer to the current time.
> +
> +   @retval EFI_SUCCESS           The operation completed successfully.
> +   @retval EFI_INVALID_PARAMETER A time field is out of range.
> +   @retval EFI_DEVICE_ERROR      The time could not be set due due to hardware error.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +LibSetTime (
> +  IN EFI_TIME  *Time
> +  )
> +{
> +  EFI_STATUS  Status;
> +  UINTN       EpochSeconds;
> +
> +  if (!IsTimeValid (Time)) {
> +    return EFI_INVALID_PARAMETER;
> +  }
> +
> +  EpochSeconds = EfiTimeToEpoch (Time);
> +
> +  // Adjust for the correct time zone, i.e. convert to UTC time zone
> +  if (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE) {
> +    EpochSeconds -= Time->TimeZone * SEC_PER_MIN;
> +  }
> +
> +  // Adjust for the correct period
> +  if ((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == EFI_TIME_IN_DAYLIGHT) {
> +    // Convert to un-adjusted time, i.e. fall back one hour
> +    EpochSeconds -= SEC_PER_HOUR;
> +  }
> +
> +  // Save the current time zone information into non-volatile storage
> +  Status = EfiSetVariable (
> +             (CHAR16 *)mTimeZoneVariableName,
> +             &gEfiCallerIdGuid,
> +             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
> +             sizeof (Time->TimeZone),
> +             (VOID *)&(Time->TimeZone)
> +             );
> +  if (EFI_ERROR (Status)) {
> +    DEBUG ((
> +      DEBUG_ERROR,
> +      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
> +      mTimeZoneVariableName,
> +      Status
> +      ));
> +    return Status;
> +  }
> +
> +  // Save the current daylight information into non-volatile storage
> +  Status = EfiSetVariable (
> +             (CHAR16 *)mDaylightVariableName,
> +             &gEfiCallerIdGuid,
> +             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
> +             sizeof(Time->Daylight),
> +             (VOID *)&(Time->Daylight)
> +           );
> +  if (EFI_ERROR (Status)) {
> +    DEBUG ((
> +      DEBUG_ERROR,
> +      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
> +      mDaylightVariableName,
> +      Status
> +      ));
> +    return Status;
> +  }
> +
> +  Status = EfiSetVariable (
> +             (CHAR16 *)mEpochVariableName,
> +             &gEfiCallerIdGuid,
> +             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
> +             sizeof (EpochSeconds),
> +             &EpochSeconds
> +             );
> +  if (EFI_ERROR (Status)) {
> +    DEBUG ((
> +      DEBUG_ERROR,
> +      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
> +      mDaylightVariableName,
> +      Status
> +      ));
> +    return Status;
> +  }
> +
> +  return EFI_SUCCESS;
> +}
> +
> +/**
> +   Returns the current wakeup alarm clock setting.
> +
> +   @param  Enabled               Indicates if the alarm is currently enabled or disabled.
> +   @param  Pending               Indicates if the alarm signal is pending and requires acknowledgement.
> +   @param  Time                  The current alarm setting.
> +
> +   @retval EFI_SUCCESS           The alarm settings were returned.
> +   @retval EFI_INVALID_PARAMETER Any parameter is NULL.
> +   @retval EFI_DEVICE_ERROR      The wakeup time could not be retrieved due to a hardware error.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +LibGetWakeupTime (
> +  OUT BOOLEAN   *Enabled,
> +  OUT BOOLEAN   *Pending,
> +  OUT EFI_TIME  *Time
> +  )
> +{
> +  return EFI_UNSUPPORTED;
> +}
> +
> +/**
> +   Sets the system wakeup alarm clock time.
> +
> +   @param  Enabled               Enable or disable the wakeup alarm.
> +   @param  Time                  If Enable is TRUE, the time to set the wakeup alarm for.
> +
> +   @retval EFI_SUCCESS           If Enable is TRUE, then the wakeup alarm was enabled. If
> +   Enable is FALSE, then the wakeup alarm was disabled.
> +   @retval EFI_INVALID_PARAMETER A time field is out of range.
> +   @retval EFI_DEVICE_ERROR      The wakeup time could not be set due to a hardware error.
> +   @retval EFI_UNSUPPORTED       A wakeup timer is not supported on this platform.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +LibSetWakeupTime (
> +  IN  BOOLEAN   Enabled,
> +  OUT EFI_TIME  *Time
> +  )
> +{
> +  return EFI_UNSUPPORTED;
> +}
> +
> +/**
> +   This is the declaration of an EFI image entry point. This can be the entry point to an application
> +   written to this specification, an EFI boot service driver, or an EFI runtime driver.
> +
> +   @param  ImageHandle           Handle that identifies the loaded image.
> +   @param  SystemTable           System Table for this image.
> +
> +   @retval EFI_SUCCESS           The operation completed successfully.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +LibRtcInitialize (
> +  IN EFI_HANDLE        ImageHandle,
> +  IN EFI_SYSTEM_TABLE  *SystemTable
> +  )
> +{
> +  return EFI_SUCCESS;
> +}
> +
> +/**
> +   Fixup internal data so that EFI can be call in virtual mode.
> +   Call the passed in Child Notify event and convert any pointers in
> +   lib to virtual mode.
> +
> +   @param[in]    Event   The Event that is being processed
> +   @param[in]    Context Event Context
> +**/
> +VOID
> +EFIAPI
> +LibRtcVirtualNotifyEvent (
> +  IN EFI_EVENT  Event,
> +  IN VOID       *Context
> +  )
> +{
> +  return;
> +}
> diff --git a/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
> new file mode 100644
> index 000000000000..ed69faad4205
> --- /dev/null
> +++ b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
> @@ -0,0 +1,43 @@
> +#/** @file
> +#
> +#  Implement virtual EFI RealTimeClock runtime services.
> +#
> +#  Copyright (c) 2019, Pete Batard <pete@akeo.ie>
> +#  Copyright (c) 2018, Andrei Warkentin <andrey.warkentin@gmail.com>
> +#  Copyright (c) Microsoft Corporation. All rights reserved.

Same issue here, 2019, alright?

> +#
> +#  This program and the accompanying materials
> +#  are licensed and made available under the terms and conditions of the BSD License
> +#  which accompanies this distribution.  The full text of the license may be found at
> +#  http://opensource.org/licenses/bsd-license.php
> +#
> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> +#
> +#**/
> +
> +[Defines]
> +  INF_VERSION                    = 0x0001001A
> +  BASE_NAME                      = VirtualRealTimeClockLib
> +  FILE_GUID                      = 1E27D461-78F3-4F7D-B1C2-F72384F13A6E
> +  MODULE_TYPE                    = BASE
> +  VERSION_STRING                 = 1.0
> +  LIBRARY_CLASS                  = RealTimeClockLib
> +
> +[Sources.common]
> +  VirtualRealTimeClockLib.c
> +
> +[Packages]
> +  MdePkg/MdePkg.dec
> +  EmbeddedPkg/EmbeddedPkg.dec
> +
> +[LibraryClasses]
> +  IoLib
> +  DebugLib
> +  TimerLib
> +  TimeBaseLib
> +  UefiRuntimeLib
> +
> +# Current usage of this library expects GCC in a UNIX-like shell environment with the date command
> +[BuildOptions]
> +  GCC:*_*_*_CC_FLAGS = -DBUILD_EPOCH=`date +%s`
> 

Re: [edk2] [PATCH 1/1] EmbeddedPkg/Library: Add VirtualRealTimeClockLib

[Pete Batard]

Hi Phil,

Not sure why this old 2019 patch suddenly appeared in your review inbox, 
but this was integrated last year as 
https://github.com/tianocore/edk2/commit/64a17fadcb79e2ce40524abb88a6863f47cbc0c7

Regards,

/Pete

On 2020.05.14 08:45, Philippe Mathieu-Daudé wrote:
> Hi Pete,
> 
> On 2/4/19 1:47 PM, Pete Batard wrote:
>> This is designed to be used on platforms where a a real RTC is not
>> available and relies on an RtcEpochSeconds variable having been set or,
>> if that is not the case, falls back to using the epoch embedded at
>> compilation time.
>>
>> Note that, in order to keep things simple for the setting of the
>> compilation time variable, only GCC environments with UNIX-like shells
>> and where a 'date' command is available are meant to be supported for
>> now.
>>
>> Contributed-under: TianoCore Contribution Agreement 1.1
>> Signed-off-by: Pete Batard <pete@akeo.ie>
>> ---
>>   
>> EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c   | 
>> 400 ++++++++++++++++++++
>>   
>> EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf |  
>> 43 +++
>>   2 files changed, 443 insertions(+)
>>
>> diff --git 
>> a/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c 
>>
>> new file mode 100644
>> index 000000000000..4c354730d02b
>> --- /dev/null
>> +++ 
>> b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
>> @@ -0,0 +1,400 @@
>> +/** @file
>> + *
>> + *  Implement virtual EFI RealTimeClock runtime services.
>> + *
>> + *  Coypright (c) 2019, Pete Batard <pete@akeo.ie>
>> + *  Copyright (c) 2018, Andrei Warkentin <andrey.warkentin@gmail.com>
>> + *  Copyright (c) 2011-2014, ARM Ltd. All rights reserved.
>> + *  Copyright (c) 2008-2010, Apple Inc. All rights reserved.
>> + *  Copyright (c) Microsoft Corporation. All rights reserved.
> 
> You forgot the year, it should be 2019 right?
> Another occurrence below.
> 
>> + *
>> + *  This program and the accompanying materials
>> + *  are licensed and made available under the terms and conditions of 
>> the BSD License
>> + *  which accompanies this distribution.  The full text of the 
>> license may be found at
>> + *  http://opensource.org/licenses/bsd-license.php
>> + *
>> + *  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" 
>> BASIS,
>> + *  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS 
>> OR IMPLIED.
>> + *
>> + *  Based on 
>> ArmPlatformPkg/Library/PL031RealTimeClockLib/PL031RealTimeClockLib.inf
>> + *
>> + **/
>> +
>> +#include <PiDxe.h>
>> +#include <Library/BaseLib.h>
>> +#include <Library/DebugLib.h>
>> +#include <Library/IoLib.h>
>> +#include <Library/RealTimeClockLib.h>
>> +#include <Library/TimerLib.h>
>> +#include <Library/TimeBaseLib.h>
>> +#include <Library/UefiRuntimeLib.h>
>> +
>> +STATIC CONST CHAR16  mEpochVariableName[]     = L"RtcEpochSeconds";
>> +STATIC CONST CHAR16  mTimeZoneVariableName[]  = L"RtcTimeZone";
>> +STATIC CONST CHAR16  mDaylightVariableName[]  = L"RtcDaylight";
>> +
>> +/**
>> +   Returns the current time and date information, and the 
>> time-keeping capabilities
>> +   of the virtual RTC.
>> +
>> +   @param  Time                  A pointer to storage to receive a 
>> snapshot of the current time.
>> +   @param  Capabilities          An optional pointer to a buffer to 
>> receive the real time clock
>> +                                 device's capabilities.
>> +
>> +   @retval EFI_SUCCESS           The operation completed successfully.
>> +   @retval EFI_INVALID_PARAMETER Time is NULL.
>> +   @retval EFI_DEVICE_ERROR      The time could not be retrieved due 
>> to hardware error.
>> +
>> +**/
>> +EFI_STATUS
>> +EFIAPI
>> +LibGetTime (
>> +  OUT EFI_TIME               *Time,
>> +  OUT EFI_TIME_CAPABILITIES  *Capabilities
>> +  )
>> +{
>> +  EFI_STATUS  Status;
>> +  UINT32      EpochSeconds;
>> +  INT16       TimeZone;
>> +  UINT8       Daylight;
>> +  UINT64      Freq;
>> +  UINT64      Counter;
>> +  UINT64      Remainder;
>> +  UINTN       ElapsedSeconds;
>> +  UINTN       Size;
>> +
>> +  if (Time == NULL) {
>> +    return EFI_INVALID_PARAMETER;
>> +  }
>> +
>> +  // Get the counter frequency
>> +  Freq = GetPerformanceCounterProperties (NULL, NULL);
>> +  if (Freq == 0) {
>> +    return EFI_DEVICE_ERROR;
>> +  }
>> +
>> +  // Get the epoch time from non-volatile storage
>> +  Size = sizeof (UINTN);
>> +  ElapsedSeconds = 0;
>> +  Status = EfiGetVariable (
>> +             (CHAR16 *)mEpochVariableName,
>> +             &gEfiCallerIdGuid,
>> +             NULL,
>> +             &Size,
>> +             (VOID *)&ElapsedSeconds
>> +             );
>> +  // Fall back to compilation-time epoch if not set
>> +  if (EFI_ERROR (Status)) {
>> +    ASSERT(Status != EFI_INVALID_PARAMETER);
>> +    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
>> +    //
>> +    // The following is intended to produce a compilation error on build
>> +    // environments where BUILD_EPOCH can not be set from inline shell.
>> +    // If you are attempting to use this library on such an 
>> environment, please
>> +    // contact the edk2 mailing list, so we can try to add support 
>> for it.
>> +    //
>> +    ElapsedSeconds = BUILD_EPOCH;
>> +    DEBUG ((
>> +      DEBUG_INFO,
>> +      "LibGetTime: %s non volatile variable was not found - Using 
>> compilation time epoch.\n",
>> +      mEpochVariableName
>> +      ));
>> +  }
>> +  Counter = GetPerformanceCounter ();
>> +  ElapsedSeconds += DivU64x64Remainder (Counter, Freq, &Remainder);
>> +
>> +  // Get the current time zone information from non-volatile storage
>> +  Size = sizeof (TimeZone);
>> +  Status = EfiGetVariable (
>> +             (CHAR16 *)mTimeZoneVariableName,
>> +             &gEfiCallerIdGuid,
>> +             NULL,
>> +             &Size,
>> +             (VOID *)&TimeZone
>> +             );
>> +
>> +  if (EFI_ERROR (Status)) {
>> +    ASSERT(Status != EFI_INVALID_PARAMETER);
>> +    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
>> +
>> +    if (Status != EFI_NOT_FOUND) {
>> +      return Status;
>> +    }
>> +
>> +    // The time zone variable does not exist in non-volatile storage, 
>> so create it.
>> +    Time->TimeZone = EFI_UNSPECIFIED_TIMEZONE;
>> +    // Store it
>> +    Status = EfiSetVariable (
>> +               (CHAR16 *)mTimeZoneVariableName,
>> +               &gEfiCallerIdGuid,
>> +               EFI_VARIABLE_NON_VOLATILE | 
>> EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
>> +               Size,
>> +               (VOID *)&(Time->TimeZone)
>> +               );
>> +    if (EFI_ERROR (Status)) {
>> +      DEBUG ((
>> +        DEBUG_ERROR,
>> +        "LibGetTime: Failed to save %s variable to non-volatile 
>> storage, Status = %r\n",
>> +        mTimeZoneVariableName,
>> +        Status
>> +        ));
>> +      return Status;
>> +    }
>> +  } else {
>> +    // Got the time zone
>> +    Time->TimeZone = TimeZone;
>> +
>> +    // Check TimeZone bounds: -1440 to 1440 or 2047
>> +    if (((Time->TimeZone < -1440) || (Time->TimeZone > 1440))
>> +        && (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE)) {
>> +      Time->TimeZone = EFI_UNSPECIFIED_TIMEZONE;
>> +    }
>> +
>> +    // Adjust for the correct time zone
>> +    if (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE) {
>> +      EpochSeconds += Time->TimeZone * SEC_PER_MIN;
>> +    }
>> +  }
>> +
>> +  // Get the current daylight information from non-volatile storage
>> +  Size = sizeof (Daylight);
>> +  Status = EfiGetVariable (
>> +             (CHAR16 *)mDaylightVariableName,
>> +             &gEfiCallerIdGuid,
>> +             NULL,
>> +             &Size,
>> +             (VOID *)&Daylight
>> +           );
>> +
>> +  if (EFI_ERROR (Status)) {
>> +    ASSERT(Status != EFI_INVALID_PARAMETER);
>> +    ASSERT(Status != EFI_BUFFER_TOO_SMALL);
>> +
>> +    if (Status != EFI_NOT_FOUND) {
>> +      return Status;
>> +    }
>> +
>> +    // The daylight variable does not exist in non-volatile storage, 
>> so create it.
>> +    Time->Daylight = 0;
>> +    // Store it
>> +    Status = EfiSetVariable (
>> +               (CHAR16 *)mDaylightVariableName,
>> +               &gEfiCallerIdGuid,
>> +               EFI_VARIABLE_NON_VOLATILE | 
>> EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
>> +               Size,
>> +               (VOID *)&(Time->Daylight)
>> +               );
>> +    if (EFI_ERROR (Status)) {
>> +      DEBUG ((
>> +        DEBUG_ERROR,
>> +        "LibGetTime: Failed to save %s variable to non-volatile 
>> storage, Status = %r\n",
>> +        mDaylightVariableName,
>> +        Status
>> +        ));
>> +      return Status;
>> +    }
>> +  } else {
>> +    // Got the daylight information
>> +    Time->Daylight = Daylight;
>> +
>> +    // Adjust for the correct period
>> +    if ((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == 
>> EFI_TIME_IN_DAYLIGHT) {
>> +      // Convert to adjusted time, i.e. spring forwards one hour
>> +      EpochSeconds += SEC_PER_HOUR;
>> +    }
>> +  }
>> +
>> +  EpochToEfiTime (ElapsedSeconds, Time);
>> +
>> +  // Because we use the performance counter, we can fill the 
>> Nanosecond attribute
>> +  // provided that the remainder doesn't overflow 64-bit during 
>> multiplication.
>> +  if (Remainder <= 18446744073U) {
>> +    Time->Nanosecond = MultU64x64 (Remainder, 1000000000U) / Freq;
>> +  } else {
>> +    DEBUG ((DEBUG_WARN, "LibGetTime: Nanosecond value not set (64-bit 
>> overflow).\n"));
>> +  }
>> +
>> +  if (Capabilities) {
>> +    Capabilities->Accuracy   = 0;
>> +    Capabilities->Resolution = Freq;
>> +    Capabilities->SetsToZero = FALSE;
>> +  }
>> +
>> +  return EFI_SUCCESS;
>> +}
>> +
>> +/**
>> +   Sets the current local time and date information.
>> +
>> +   @param  Time                  A pointer to the current time.
>> +
>> +   @retval EFI_SUCCESS           The operation completed successfully.
>> +   @retval EFI_INVALID_PARAMETER A time field is out of range.
>> +   @retval EFI_DEVICE_ERROR      The time could not be set due due to 
>> hardware error.
>> +
>> +**/
>> +EFI_STATUS
>> +EFIAPI
>> +LibSetTime (
>> +  IN EFI_TIME  *Time
>> +  )
>> +{
>> +  EFI_STATUS  Status;
>> +  UINTN       EpochSeconds;
>> +
>> +  if (!IsTimeValid (Time)) {
>> +    return EFI_INVALID_PARAMETER;
>> +  }
>> +
>> +  EpochSeconds = EfiTimeToEpoch (Time);
>> +
>> +  // Adjust for the correct time zone, i.e. convert to UTC time zone
>> +  if (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE) {
>> +    EpochSeconds -= Time->TimeZone * SEC_PER_MIN;
>> +  }
>> +
>> +  // Adjust for the correct period
>> +  if ((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == EFI_TIME_IN_DAYLIGHT) {
>> +    // Convert to un-adjusted time, i.e. fall back one hour
>> +    EpochSeconds -= SEC_PER_HOUR;
>> +  }
>> +
>> +  // Save the current time zone information into non-volatile storage
>> +  Status = EfiSetVariable (
>> +             (CHAR16 *)mTimeZoneVariableName,
>> +             &gEfiCallerIdGuid,
>> +             EFI_VARIABLE_NON_VOLATILE | 
>> EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
>> +             sizeof (Time->TimeZone),
>> +             (VOID *)&(Time->TimeZone)
>> +             );
>> +  if (EFI_ERROR (Status)) {
>> +    DEBUG ((
>> +      DEBUG_ERROR,
>> +      "LibSetTime: Failed to save %s variable to non-volatile 
>> storage, Status = %r\n",
>> +      mTimeZoneVariableName,
>> +      Status
>> +      ));
>> +    return Status;
>> +  }
>> +
>> +  // Save the current daylight information into non-volatile storage
>> +  Status = EfiSetVariable (
>> +             (CHAR16 *)mDaylightVariableName,
>> +             &gEfiCallerIdGuid,
>> +             EFI_VARIABLE_NON_VOLATILE | 
>> EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
>> +             sizeof(Time->Daylight),
>> +             (VOID *)&(Time->Daylight)
>> +           );
>> +  if (EFI_ERROR (Status)) {
>> +    DEBUG ((
>> +      DEBUG_ERROR,
>> +      "LibSetTime: Failed to save %s variable to non-volatile 
>> storage, Status = %r\n",
>> +      mDaylightVariableName,
>> +      Status
>> +      ));
>> +    return Status;
>> +  }
>> +
>> +  Status = EfiSetVariable (
>> +             (CHAR16 *)mEpochVariableName,
>> +             &gEfiCallerIdGuid,
>> +             EFI_VARIABLE_NON_VOLATILE | 
>> EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
>> +             sizeof (EpochSeconds),
>> +             &EpochSeconds
>> +             );
>> +  if (EFI_ERROR (Status)) {
>> +    DEBUG ((
>> +      DEBUG_ERROR,
>> +      "LibSetTime: Failed to save %s variable to non-volatile 
>> storage, Status = %r\n",
>> +      mDaylightVariableName,
>> +      Status
>> +      ));
>> +    return Status;
>> +  }
>> +
>> +  return EFI_SUCCESS;
>> +}
>> +
>> +/**
>> +   Returns the current wakeup alarm clock setting.
>> +
>> +   @param  Enabled               Indicates if the alarm is currently 
>> enabled or disabled.
>> +   @param  Pending               Indicates if the alarm signal is 
>> pending and requires acknowledgement.
>> +   @param  Time                  The current alarm setting.
>> +
>> +   @retval EFI_SUCCESS           The alarm settings were returned.
>> +   @retval EFI_INVALID_PARAMETER Any parameter is NULL.
>> +   @retval EFI_DEVICE_ERROR      The wakeup time could not be 
>> retrieved due to a hardware error.
>> +
>> +**/
>> +EFI_STATUS
>> +EFIAPI
>> +LibGetWakeupTime (
>> +  OUT BOOLEAN   *Enabled,
>> +  OUT BOOLEAN   *Pending,
>> +  OUT EFI_TIME  *Time
>> +  )
>> +{
>> +  return EFI_UNSUPPORTED;
>> +}
>> +
>> +/**
>> +   Sets the system wakeup alarm clock time.
>> +
>> +   @param  Enabled               Enable or disable the wakeup alarm.
>> +   @param  Time                  If Enable is TRUE, the time to set 
>> the wakeup alarm for.
>> +
>> +   @retval EFI_SUCCESS           If Enable is TRUE, then the wakeup 
>> alarm was enabled. If
>> +   Enable is FALSE, then the wakeup alarm was disabled.
>> +   @retval EFI_INVALID_PARAMETER A time field is out of range.
>> +   @retval EFI_DEVICE_ERROR      The wakeup time could not be set due 
>> to a hardware error.
>> +   @retval EFI_UNSUPPORTED       A wakeup timer is not supported on 
>> this platform.
>> +
>> +**/
>> +EFI_STATUS
>> +EFIAPI
>> +LibSetWakeupTime (
>> +  IN  BOOLEAN   Enabled,
>> +  OUT EFI_TIME  *Time
>> +  )
>> +{
>> +  return EFI_UNSUPPORTED;
>> +}
>> +
>> +/**
>> +   This is the declaration of an EFI image entry point. This can be 
>> the entry point to an application
>> +   written to this specification, an EFI boot service driver, or an 
>> EFI runtime driver.
>> +
>> +   @param  ImageHandle           Handle that identifies the loaded 
>> image.
>> +   @param  SystemTable           System Table for this image.
>> +
>> +   @retval EFI_SUCCESS           The operation completed successfully.
>> +
>> +**/
>> +EFI_STATUS
>> +EFIAPI
>> +LibRtcInitialize (
>> +  IN EFI_HANDLE        ImageHandle,
>> +  IN EFI_SYSTEM_TABLE  *SystemTable
>> +  )
>> +{
>> +  return EFI_SUCCESS;
>> +}
>> +
>> +/**
>> +   Fixup internal data so that EFI can be call in virtual mode.
>> +   Call the passed in Child Notify event and convert any pointers in
>> +   lib to virtual mode.
>> +
>> +   @param[in]    Event   The Event that is being processed
>> +   @param[in]    Context Event Context
>> +**/
>> +VOID
>> +EFIAPI
>> +LibRtcVirtualNotifyEvent (
>> +  IN EFI_EVENT  Event,
>> +  IN VOID       *Context
>> +  )
>> +{
>> +  return;
>> +}
>> diff --git 
>> a/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf 
>> b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
>> new file mode 100644
>> index 000000000000..ed69faad4205
>> --- /dev/null
>> +++ 
>> b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
>> @@ -0,0 +1,43 @@
>> +#/** @file
>> +#
>> +#  Implement virtual EFI RealTimeClock runtime services.
>> +#
>> +#  Copyright (c) 2019, Pete Batard <pete@akeo.ie>
>> +#  Copyright (c) 2018, Andrei Warkentin <andrey.warkentin@gmail.com>
>> +#  Copyright (c) Microsoft Corporation. All rights reserved.
> 
> Same issue here, 2019, alright?
> 
>> +#
>> +#  This program and the accompanying materials
>> +#  are licensed and made available under the terms and conditions of 
>> the BSD License
>> +#  which accompanies this distribution.  The full text of the license 
>> may be found at
>> +#  http://opensource.org/licenses/bsd-license.php
>> +#
>> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS 
>> OR IMPLIED.
>> +#
>> +#**/
>> +
>> +[Defines]
>> +  INF_VERSION                    = 0x0001001A
>> +  BASE_NAME                      = VirtualRealTimeClockLib
>> +  FILE_GUID                      = 1E27D461-78F3-4F7D-B1C2-F72384F13A6E
>> +  MODULE_TYPE                    = BASE
>> +  VERSION_STRING                 = 1.0
>> +  LIBRARY_CLASS                  = RealTimeClockLib
>> +
>> +[Sources.common]
>> +  VirtualRealTimeClockLib.c
>> +
>> +[Packages]
>> +  MdePkg/MdePkg.dec
>> +  EmbeddedPkg/EmbeddedPkg.dec
>> +
>> +[LibraryClasses]
>> +  IoLib
>> +  DebugLib
>> +  TimerLib
>> +  TimeBaseLib
>> +  UefiRuntimeLib
>> +
>> +# Current usage of this library expects GCC in a UNIX-like shell 
>> environment with the date command
>> +[BuildOptions]
>> +  GCC:*_*_*_CC_FLAGS = -DBUILD_EPOCH=`date +%s`
>>
>