[PATCH] StandaloneMmPkg: Support CLANGPDB X64 builds

["Marvin Häuser" <mhaeuser@posteo.de>]

Currently, the flag "-fpie" is passed for all builds with a GCC
family toolchain, including CLANGPDB. CLANGPDB however does not
support this flag as it generates PE/COFF files directly.

As the flag is mostly required for AArch64-specific self-relocation,
drop it for X64 builds and document the limitation to enable X64
CLANGPDB builds of StandaloneMmCore.

Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Sami Mujawar <sami.mujawar@arm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Supreeth Venkatesh <supreeth.venkatesh@arm.com>
Cc: Vitaly Cheptsov <vit9696@protonmail.com>
Signed-off-by: Marvin Häuser <mhaeuser@posteo.de>
---
 StandaloneMmPkg/Core/StandaloneMmCore.inf                                         | 9 +++++++--
 StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/StandaloneMmCoreEntryPoint.inf | 7 ++++++-
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/StandaloneMmPkg/Core/StandaloneMmCore.inf b/StandaloneMmPkg/Core/StandaloneMmCore.inf
index 87bf6e9440a7..e3349fff29cc 100644
--- a/StandaloneMmPkg/Core/StandaloneMmCore.inf
+++ b/StandaloneMmPkg/Core/StandaloneMmCore.inf
@@ -76,6 +76,11 @@ [Guids]
   gEfiEventExitBootServicesGuid
   gEfiEventReadyToBootGuid
 
+#
+# This configuration fails for CLANGPDB, which does not support PIE in the GCC
+# sense. Such however is required for AArch64 StandaloneMmCore self-relocation,
+# and thus the CLANGPDB toolchain is unsupported for AArch64 for this module.
+#
 [BuildOptions]
-  GCC:*_*_*_CC_FLAGS = -fpie
-  GCC:*_*_*_DLINK_FLAGS = -Wl,-z,text,-Bsymbolic,-pie
+  GCC:*_*_AARCH64_CC_FLAGS = -fpie
+  GCC:*_*_AARCH64_DLINK_FLAGS = -Wl,-z,text,-Bsymbolic,-pie
diff --git a/StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/StandaloneMmCoreEntryPoint.inf b/StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/StandaloneMmCoreEntryPoint.inf
index 4fa426f58ef4..dcbb082d4ab8 100644
--- a/StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/StandaloneMmCoreEntryPoint.inf
+++ b/StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/StandaloneMmCoreEntryPoint.inf
@@ -54,5 +54,10 @@ [Guids]
 [FeaturePcd.AARCH64]
   gArmTokenSpaceGuid.PcdFfaEnable
 
+#
+# This configuration fails for CLANGPDB, which does not support PIE in the GCC
+# sense. Such however is required for AArch64 StandaloneMmCore self-relocation,
+# and thus the CLANGPDB toolchain is unsupported for AArch64 for this module.
+#
 [BuildOptions]
-  GCC:*_*_*_CC_FLAGS = -fpie
+  GCC:*_*_AARCH64_CC_FLAGS = -fpie
-- 
2.31.1