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UefiCpuPkg/MtrrLib: Add PCD PcdCpuNumberOfReservedVariableMtrrs

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Current MtrrLib reserves 2 variable MTRRs for some legacy OS boot (CSM boots)
may require some MTRRs to be reserved for OS use. But UEFI OS boot will not use
MTRRs.

Per Scott's suggestion in
link: http://article.gmane.org/gmane.comp.bios.edk2.devel/4099
Add one PCD PcdCpuNumberOfReservedVariableMtrrs to specify the number of
variable MTRRs reserved for OS use. Setting its default value to 2 is for
back-compatibility.

Cc: Scott Duplichan <scott@notabs.org>
Cc: Feng Tian <feng.tian@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jeff Fan <jeff.fan@intel.com>
Suggested-by: Scott Duplichan <scott@notabs.org>
Reviewed-by: Feng Tian <feng.tian@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19151 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
Jeff Fan
2015-12-08 05:19:34 +00:00
committed by vanjeff
parent 5c1edc5534
commit 46309b1101
4 changed files with 15 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
UefiCpuPkg/Library/MtrrLib/MtrrLib.c
View File

@@ -140,13 +140,15 @@ GetFirmwareVariableMtrrCount (
)
{
UINT32 VariableMtrrCount;
UINT32 ReservedMtrrNumber;
VariableMtrrCount = GetVariableMtrrCount ();
if (VariableMtrrCount < RESERVED_FIRMWARE_VARIABLE_MTRR_NUMBER) {
ReservedMtrrNumber = PcdGet32 (PcdCpuNumberOfReservedVariableMtrrs);
if (VariableMtrrCount < ReservedMtrrNumber) {
return 0;
}
return VariableMtrrCount - RESERVED_FIRMWARE_VARIABLE_MTRR_NUMBER;
return VariableMtrrCount - ReservedMtrrNumber;
}
/**