[RFC PATCH 6/7] ArmVirtPkg/MemoryInitPeiLib: split memory HOB based on MAX_ALLOC_ADDRESS

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

The current ArmVirtMemoryInitPeiLib code splits the memory region passed
via PcdSystemMemoryBase/PcdSystemMemorySize in two if the region extends
beyond the MAX_ADDRESS limit. This was introduced for 32-bit ARM, which
may support more than 4 GB of physical address space, but cannot address
all of it via a 1:1 mapping, and a single region that is not mappable
in its entirety is unusable by the PEI core.

AArch64 is in a similar situation now: platforms may support more than
256 TB of physical address space, but only 256 TB is addressable by the
CPU, and so a memory region that extends from below this limit to above
it should be split.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 ArmVirtPkg/Library/ArmVirtMemoryInitPeiLib/ArmVirtMemoryInitPeiLib.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/ArmVirtPkg/Library/ArmVirtMemoryInitPeiLib/ArmVirtMemoryInitPeiLib.c b/ArmVirtPkg/Library/ArmVirtMemoryInitPeiLib/ArmVirtMemoryInitPeiLib.c
index 05afd1282422..66925fc05ebd 100644
--- a/ArmVirtPkg/Library/ArmVirtMemoryInitPeiLib/ArmVirtMemoryInitPeiLib.c
+++ b/ArmVirtPkg/Library/ArmVirtMemoryInitPeiLib/ArmVirtMemoryInitPeiLib.c
@@ -75,18 +75,18 @@ MemoryPeim (
   SystemMemoryTop = PcdGet64 (PcdSystemMemoryBase) +
                     PcdGet64 (PcdSystemMemorySize);
 
-  if (SystemMemoryTop - 1 > MAX_ADDRESS) {
+  if (SystemMemoryTop - 1 > MAX_ALLOC_ADDRESS) {
     BuildResourceDescriptorHob (
         EFI_RESOURCE_SYSTEM_MEMORY,
         ResourceAttributes,
         PcdGet64 (PcdSystemMemoryBase),
-        (UINT64)MAX_ADDRESS - PcdGet64 (PcdSystemMemoryBase) + 1
+        (UINT64)MAX_ALLOC_ADDRESS - PcdGet64 (PcdSystemMemoryBase) + 1
         );
     BuildResourceDescriptorHob (
         EFI_RESOURCE_SYSTEM_MEMORY,
         ResourceAttributes,
-        (UINT64)MAX_ADDRESS + 1,
-        SystemMemoryTop - MAX_ADDRESS - 1
+        (UINT64)MAX_ALLOC_ADDRESS + 1,
+        SystemMemoryTop - MAX_ALLOC_ADDRESS - 1
         );
   } else {
     BuildResourceDescriptorHob (
-- 
2.19.2