[PATCH v4 02/12] Revert "ArmVirtPkg/FdtClientDxe: install DT configuration table at ReadyToBoot"

[Laszlo Ersek <lersek@redhat.com>]

This reverts commit 18f6d4df9ece8b91b86511bcdd1cf7da478c3627.

We realized that DXE drivers that are independent of AcpiPlatformDxe (that
is, independent of QEMU's ACPI generation), such as RamDiskDxe and
BootGraphicsResourceTableDxe, may produce and/or manipulate ACPI tables,
at driver dispatch or even at Ready To Boot.

This makes it unsafe for us to check for ACPI presence in the UEFI system
config table in a Ready To Boot callback, in order to decide about
exposing the DT.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---

Notes:
    v3:
    - pick up Ard's R-b

 ArmVirtPkg/FdtClientDxe/FdtClientDxe.inf |  1 -
 ArmVirtPkg/FdtClientDxe/FdtClientDxe.c   | 49 ++++----------------
 2 files changed, 9 insertions(+), 41 deletions(-)

diff --git a/ArmVirtPkg/FdtClientDxe/FdtClientDxe.inf b/ArmVirtPkg/FdtClientDxe/FdtClientDxe.inf
index 00017727c32c..3a0cd37040eb 100644
--- a/ArmVirtPkg/FdtClientDxe/FdtClientDxe.inf
+++ b/ArmVirtPkg/FdtClientDxe/FdtClientDxe.inf
@@ -42,7 +42,6 @@ [Protocols]
   gFdtClientProtocolGuid                  ## PRODUCES
 
 [Guids]
-  gEfiEventReadyToBootGuid
   gFdtHobGuid
   gFdtTableGuid
 
diff --git a/ArmVirtPkg/FdtClientDxe/FdtClientDxe.c b/ArmVirtPkg/FdtClientDxe/FdtClientDxe.c
index 4cf79f70cb2a..547a29fce62c 100644
--- a/ArmVirtPkg/FdtClientDxe/FdtClientDxe.c
+++ b/ArmVirtPkg/FdtClientDxe/FdtClientDxe.c
@@ -20,7 +20,6 @@
 #include <Library/HobLib.h>
 #include <libfdt.h>
 
-#include <Guid/EventGroup.h>
 #include <Guid/Fdt.h>
 #include <Guid/FdtHob.h>
 
@@ -307,30 +306,6 @@ STATIC FDT_CLIENT_PROTOCOL mFdtClientProtocol = {
   GetOrInsertChosenNode,
 };
 
-STATIC
-VOID
-EFIAPI
-OnReadyToBoot (
-  EFI_EVENT       Event,
-  VOID            *Context
-  )
-{
-  EFI_STATUS      Status;
-
-  if (!FeaturePcdGet (PcdPureAcpiBoot)) {
-    //
-    // Only install the FDT as a configuration table if we want to leave it up
-    // to the OS to decide whether it prefers ACPI over DT.
-    //
-    Status = gBS->InstallConfigurationTable (&gFdtTableGuid, mDeviceTreeBase);
-    ASSERT_EFI_ERROR (Status);
-  }
-
-  gBS->CloseEvent (Event);
-}
-
-STATIC EFI_EVENT         mReadyToBootEvent;
-
 EFI_STATUS
 EFIAPI
 InitializeFdtClientDxe (
@@ -358,21 +333,15 @@ InitializeFdtClientDxe (
 
   DEBUG ((EFI_D_INFO, "%a: DTB @ 0x%p\n", __FUNCTION__, mDeviceTreeBase));
 
-  Status = gBS->InstallProtocolInterface (&ImageHandle, &gFdtClientProtocolGuid,
-                  EFI_NATIVE_INTERFACE, &mFdtClientProtocol);
-  if (EFI_ERROR (Status)) {
-    return Status;
+  if (!FeaturePcdGet (PcdPureAcpiBoot)) {
+    //
+    // Only install the FDT as a configuration table if we want to leave it up
+    // to the OS to decide whether it prefers ACPI over DT.
+    //
+    Status = gBS->InstallConfigurationTable (&gFdtTableGuid, DeviceTreeBase);
+    ASSERT_EFI_ERROR (Status);
   }
 
-  Status = gBS->CreateEventEx (
-                  EVT_NOTIFY_SIGNAL,
-                  TPL_CALLBACK,
-                  OnReadyToBoot,
-                  NULL,
-                  &gEfiEventReadyToBootGuid,
-                  &mReadyToBootEvent
-                  );
-  ASSERT_EFI_ERROR (Status);
-
-  return EFI_SUCCESS;
+  return gBS->InstallProtocolInterface (&ImageHandle, &gFdtClientProtocolGuid,
+                EFI_NATIVE_INTERFACE, &mFdtClientProtocol);
 }
-- 
2.9.3