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

[Leif Lindholm <leif.lindholm@linaro.org>]

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
> > > 
>