[PATCH edk2-platforms v1 1/1] Platform/ARM: Reduce System Memory Size for FVP with RME extensions

["Sami Mujawar" <sami.mujawar@arm.com>]

For older FVPs (without support for RME extension) the top 16MB of
DRAM1 is reserved as Trusted DRAM. However, the latest FVP Base RevC
AEM Model [1] has support for RME extension. When RME extension is
present the top 64MB of DRAM1 (i.e. at the top of the 32bit address
space) is carved out for four-world support in TF-A [2].

Therefore, reduce the System Memory size by 64MB.

Reference:
[1] FVP Base RevC AEM Model (available on x86_64 / Arm64 Linux)
(https://developer.arm.com/Tools%20and%20Software/
Fixed%20Virtual%20Platforms)

[2] commit c872072 (https://review.trustedfirmware.org/plugins/gitiles/
TF-A/trusted-firmware-a/+/c8720729726faffc39ec64f3a02440a48c8c305a))

Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
---
 Platform/ARM/VExpressPkg/ArmVExpress-FVP-AArch64.dsc | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/Platform/ARM/VExpressPkg/ArmVExpress-FVP-AArch64.dsc b/Platform/ARM/VExpressPkg/ArmVExpress-FVP-AArch64.dsc
index dc081794cf98a27c667ef85bd27dacd80e9e8bd2..f70a4d52ba06f570e017ab5286f06d87193753e5 100644
--- a/Platform/ARM/VExpressPkg/ArmVExpress-FVP-AArch64.dsc
+++ b/Platform/ARM/VExpressPkg/ArmVExpress-FVP-AArch64.dsc
@@ -107,9 +107,12 @@ [PcdsFixedAtBuild.common]
   gArmPlatformTokenSpaceGuid.PcdCPUCorePrimaryStackSize|0x4000
   gArmPlatformTokenSpaceGuid.PcdCPUCoreSecondaryStackSize|0x0
 
-  # System Memory (2GB - 16MB of Trusted DRAM at the top of the 32bit address space)
+  # System Memory
+  # When RME is supported by the FVP the top 64MB of DRAM1 (i.e. at the top
+  # of the 32bit address space) is reserved for four-world support in TF-A.
+  # Therefore, set the default System Memory size to (2GB - 64MB).
   gArmTokenSpaceGuid.PcdSystemMemoryBase|0x80000000
-  gArmTokenSpaceGuid.PcdSystemMemorySize|0x7F000000
+  gArmTokenSpaceGuid.PcdSystemMemorySize|0x7C000000
 
   # Size of the region used by UEFI in permanent memory (Reserved 64MB)
   gArmPlatformTokenSpaceGuid.PcdSystemMemoryUefiRegionSize|0x04000000
-- 
'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'