Re: [edk2-devel] [PATCH v1 1/1] StandaloneMmPkg: Initialise serial port early in StandaloneMmEntryPoint

["levi.yun" <yeoreum.yun@arm.com>]

+ ardb+tianocore@kernel.org

________________________________________
From: levi.yun <yeoreum.yun@arm.com>
Sent: 05 January 2024 11:49
To: devel@edk2.groups.io
Cc: Yeo Reum Yun; ard.biesheuvel@linaro.org; Sami Mujawar; ray.ni@intel.com; Pierre Gondois; nd
Subject: [PATCH v1 1/1] StandaloneMmPkg: Initialise serial port early in StandaloneMmEntryPoint

Serial port used by the DEBUG macro is initialised in StandaloneMmMain
by the DebugLib constructor.

When we use a serial port initialised by TF-A it is not a problem.
However, if we use a serial port that is not initialised by TF-A,
the debug log prints hangs.

Therefore, initialise the serial port early on in the entry point.

Signed-off-by: levi.yun <yeoreum.yun@arm.com>
---
These changes can be seen at
https://github.com/LeviYeoReum/edk2/tree/levi/2956_init_serial too.

 StandaloneMmPkg/StandaloneMmPkg.dsc                                                 | 1 +
 StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/StandaloneMmCoreEntryPoint.inf   | 1 +
 StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/Arm/StandaloneMmCoreEntryPoint.c | 3 +++
 3 files changed, 5 insertions(+)

diff --git a/StandaloneMmPkg/StandaloneMmPkg.dsc b/StandaloneMmPkg/StandaloneMmPkg.dsc
index 8012f93b7dcc38ea8fdd2de98912bbc09157ec53..040a4aa5b3d268fdfaaec9a975cfc6ff31aa37b4 100644
--- a/StandaloneMmPkg/StandaloneMmPkg.dsc
+++ b/StandaloneMmPkg/StandaloneMmPkg.dsc
@@ -66,6 +66,7 @@ [LibraryClasses.AARCH64, LibraryClasses.ARM]
   ArmSvcLib|ArmPkg/Library/ArmSvcLib/ArmSvcLib.inf
   CacheMaintenanceLib|ArmPkg/Library/ArmCacheMaintenanceLib/ArmCacheMaintenanceLib.inf
   PeCoffExtraActionLib|StandaloneMmPkg/Library/StandaloneMmPeCoffExtraActionLib/StandaloneMmPeCoffExtraActionLib.inf
+  SerialPortLib|MdePkg/Library/BaseSerialPortLibNull/BaseSerialPortLibNull.inf

   NULL|ArmPkg/Library/CompilerIntrinsicsLib/CompilerIntrinsicsLib.inf
   NULL|MdePkg/Library/BaseStackCheckLib/BaseStackCheckLib.inf
diff --git a/StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/StandaloneMmCoreEntryPoint.inf b/StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/StandaloneMmCoreEntryPoint.inf
index 75cfb98c0e75cd7cee2a59723035679612da4528..086639ecfbc983627aed73817815e2485104375e 100644
--- a/StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/StandaloneMmCoreEntryPoint.inf
+++ b/StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/StandaloneMmCoreEntryPoint.inf
@@ -42,6 +42,7 @@ [LibraryClasses]
   DebugLib

 [LibraryClasses.ARM, LibraryClasses.AARCH64]
+  SerialPortLib
   StandaloneMmMmuLib
   ArmSvcLib

diff --git a/StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/Arm/StandaloneMmCoreEntryPoint.c b/StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/Arm/StandaloneMmCoreEntryPoint.c
index 96de10405af829c66e3f43ed4692f785d8df113e..66b56bdfe4959d5ab6152ff024caa6e900e7a948 100644
--- a/StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/Arm/StandaloneMmCoreEntryPoint.c
+++ b/StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/Arm/StandaloneMmCoreEntryPoint.c
@@ -335,6 +335,9 @@ _ModuleEntryPoint (
   UINTN                           TeDataSize;
   EFI_PHYSICAL_ADDRESS            ImageBase;

+  // Initialize the Serial Port early to print debug log before StandaloneMmMain.
+  SerialPortInitialize ();
+
   // Get Secure Partition Manager Version Information
   Status = GetSpmVersion ();
   if (EFI_ERROR (Status)) {
--
Guid("CE165669-3EF3-493F-B85D-6190EE5B9759")

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