From 9bdf791f7dd167b1a9ad6b3d877d96492cc834bf Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date: Mon, 10 Aug 2015 07:54:55 +0000
Subject: ArmPlatformPkg/ArmJunoPkg: use a rodata symbol for ReferenceAcpiTable

The ACPI .aslc files contain a ReferenceAcpiTable() function whose
sole purpose is to ensure that the table itself does not get optimized
away. However, when using clang, these dummy functions result in a 4 KB
section alignment requirement, which is silly since everything except
the .data section is discarded later anyway.

So instead, make ReferenceAcpiTable a CONST pointer to VOID*. This way,
we still have a .text section, which is mandatory for the PE/COFF
conversion, but no executable code with small model relocations that
impose additional alignment requirements.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
Tested-by: Leif Lindholm <leif.lindholm@linaro.org>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18194 6f19259b-4bc3-4df7-8a09-765794883524
---
 ArmPlatformPkg/ArmJunoPkg/AcpiTables/Facs.aslc | 16 +++++-----------
 ArmPlatformPkg/ArmJunoPkg/AcpiTables/Fadt.aslc | 16 +++++-----------
 ArmPlatformPkg/ArmJunoPkg/AcpiTables/Gtdt.aslc | 16 +++++-----------
 ArmPlatformPkg/ArmJunoPkg/AcpiTables/Madt.aslc | 16 +++++-----------
 4 files changed, 20 insertions(+), 44 deletions(-)

diff --git a/ArmPlatformPkg/ArmJunoPkg/AcpiTables/Facs.aslc b/ArmPlatformPkg/ArmJunoPkg/AcpiTables/Facs.aslc
index 9743ddb5ee..137ead77c1 100644
--- a/ArmPlatformPkg/ArmJunoPkg/AcpiTables/Facs.aslc
+++ b/ArmPlatformPkg/ArmJunoPkg/AcpiTables/Facs.aslc
@@ -55,14 +55,8 @@ EFI_ACPI_5_0_FIRMWARE_ACPI_CONTROL_STRUCTURE Facs = {
       EFI_ACPI_RESERVED_BYTE },                           // UINT8   Reserved1[23]
 };
 
-VOID*
-ReferenceAcpiTable (
-  VOID
-  )
-{
-  //
-  // Reference the table being generated to prevent the optimizer from removing the
-  // data structure from the executable
-  //
-  return (VOID*)&Facs;
-}
+//
+// Reference the table being generated to prevent the optimizer from removing the
+// data structure from the executable
+//
+VOID* CONST ReferenceAcpiTable = &Facs;
diff --git a/ArmPlatformPkg/ArmJunoPkg/AcpiTables/Fadt.aslc b/ArmPlatformPkg/ArmJunoPkg/AcpiTables/Fadt.aslc
index ef6d786b7c..eafdecb8af 100644
--- a/ArmPlatformPkg/ArmJunoPkg/AcpiTables/Fadt.aslc
+++ b/ArmPlatformPkg/ArmJunoPkg/AcpiTables/Fadt.aslc
@@ -92,14 +92,8 @@ EFI_ACPI_5_1_FIXED_ACPI_DESCRIPTION_TABLE Fadt = {
   NULL_GAS                                                                  // EFI_ACPI_5_0_GENERIC_ADDRESS_STRUCTURE  SleepStatusReg
 };
 
-VOID*
-ReferenceAcpiTable (
-  VOID
-  )
-{
-  //
-  // Reference the table being generated to prevent the optimizer from removing the
-  // data structure from the executable
-  //
-  return (VOID*)&Fadt;
-}
+//
+// Reference the table being generated to prevent the optimizer from removing the
+// data structure from the executable
+//
+VOID* CONST ReferenceAcpiTable = &Fadt;
diff --git a/ArmPlatformPkg/ArmJunoPkg/AcpiTables/Gtdt.aslc b/ArmPlatformPkg/ArmJunoPkg/AcpiTables/Gtdt.aslc
index 49d6e8e213..50057c2641 100644
--- a/ArmPlatformPkg/ArmJunoPkg/AcpiTables/Gtdt.aslc
+++ b/ArmPlatformPkg/ArmJunoPkg/AcpiTables/Gtdt.aslc
@@ -96,14 +96,8 @@
   };
 #endif
 
-VOID*
-ReferenceAcpiTable (
-  VOID
-  )
-{
-  //
-  // Reference the table being generated to prevent the optimizer from removing the
-  // data structure from the exeutable
-  //
-  return (VOID*)&Gtdt;
-}
+//
+// Reference the table being generated to prevent the optimizer from removing the
+// data structure from the executable
+//
+VOID* CONST ReferenceAcpiTable = &Gtdt;
diff --git a/ArmPlatformPkg/ArmJunoPkg/AcpiTables/Madt.aslc b/ArmPlatformPkg/ArmJunoPkg/AcpiTables/Madt.aslc
index f8f50800c0..406bd94f56 100644
--- a/ArmPlatformPkg/ArmJunoPkg/AcpiTables/Madt.aslc
+++ b/ArmPlatformPkg/ArmJunoPkg/AcpiTables/Madt.aslc
@@ -123,14 +123,8 @@
   };
 #endif
 
-VOID*
-ReferenceAcpiTable (
-  VOID
-  )
-{
-  //
-  // Reference the table being generated to prevent the optimizer from removing the
-  // data structure from the executable
-  //
-  return (VOID*)&Madt;
-}
+//
+// Reference the table being generated to prevent the optimizer from removing the
+// data structure from the executable
+//
+VOID* CONST ReferenceAcpiTable = &Madt;
-- 
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