From: "Wang, Jian J" <[email protected]>
PCD PcdNullPointerDetectionPropertyMask is a bitmask used to control the
NULL address detection functionality in code for different phases.
If enabled, accessing NULL address in UEFI or SMM code can be caught
as a page fault exception.
BIT0 - Enable NULL pointer detection for UEFI.
BIT1 - Enable NULL pointer detection for SMM.
BIT2..6 - Reserved for future uses.
BIT7 - Disable NULL pointer detection just after EndOfDxe. This is a
workaround for those unsolvable NULL access issues in
OptionROM, boot loader, etc. It can also help to avoid
unnecessary exception caused by legacy memory (0-4095) access
after EndOfDxe, such as Windows 7 boot on Qemu.
Cc: Star Zeng <[email protected]>
Cc: Eric Dong <[email protected]>
Cc: Laszlo Ersek <[email protected]>
Cc: Jiewen Yao <[email protected]>
Cc: Michael Kinney <[email protected]>
Cc: Jordan Justen <[email protected]>
Cc: Ayellet Wolman <[email protected]>
Suggested-by: Ayellet Wolman <[email protected]>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <[email protected]>
---
MdeModulePkg/MdeModulePkg.dec | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec
index 403a66a5ad..3f90b8d7e6 100644
--- a/MdeModulePkg/MdeModulePkg.dec
+++ b/MdeModulePkg/MdeModulePkg.dec
@@ -863,6 +863,19 @@
# @ValidList 0x80000006 | 0x03058002
gEfiMdeModulePkgTokenSpaceGuid.PcdErrorCodeSetVariable|0x03058002|UINT32|0x30001040
+ ## Mask to control the NULL address detection in code for different phases.
+ # If enabled, accessing NULL address in UEFI or SMM code can be
caught.<BR><BR>
+ # BIT0 - Enable NULL pointer detection for UEFI.<BR>
+ # BIT1 - Enable NULL pointer detection for SMM.<BR>
+ # BIT2..6 - Reserved for future uses.<BR>
+ # BIT7 - Disable NULL pointer detection just after EndOfDxe. <BR>
+ # This is a workaround for those unsolvable NULL access issues
in
+ # OptionROM, boot loader, etc. It can also help to avoid
unnecessary
+ # exception caused by legacy memory (0-4095) access after
EndOfDxe,
+ # such as Windows 7 boot on Qemu.<BR>
+ # @Prompt Enable NULL address detection.
+
gEfiMdeModulePkgTokenSpaceGuid.PcdNullPointerDetectionPropertyMask|0x0|UINT8|0x30001050
+
[PcdsFixedAtBuild, PcdsPatchableInModule]
## Dynamic type PCD can be registered callback function for Pcd setting
action.
# PcdMaxPeiPcdCallBackNumberPerPcdEntry indicates the maximum number of
callback function
--
2.14.1.windows.1
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