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UefiCpuPkg: Explain relationship between several SMM PCDs 

There are three PCDs that may impact the behavior of each other in
SMM environment:
  PcdCpuSmmProfileEnable
  PcdHeapGuardPropertyMask in MdeModulePkg
  PcdCpuSmmRestrictedMemoryAccess

The patch updates the comments in DEC file to document it.

Signed-off-by: Ray Ni <ray.ni@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
This commit is contained in:
Ray Ni 2019-08-26 06:27:13 +08:00
parent 79186ddcdd
commit f64a597d45
1 changed files with 7 additions and 1 deletions
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8
UefiCpuPkg/UefiCpuPkg.dec
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@ -81,7 +81,8 @@
[PcdsFeatureFlag]
## Indicates if SMM Profile will be enabled.
# If enabled, instruction executions in and data accesses to memory outside of SMRAM will be logged.
# It could not be enabled at the same time with SMM static page table feature (PcdCpuSmmStaticPageTable).
# In X64 build, it could not be enabled when PcdCpuSmmRestrictedMemoryAccess is TRUE.
# In IA32 build, the page table memory is not marked as read-only when it is enabled.
# This PCD is only for validation purpose. It should be set to false in production.<BR><BR>
# TRUE - SMM Profile will be enabled.<BR>
# FALSE - SMM Profile will be disabled.<BR>
@ -285,6 +286,11 @@
# The PCD value is considered as constantly TRUE in IA32 platforms.
# When the PCD value is TRUE, page table is initialized to cover all memory spaces
# and the memory occupied by page table is protected by page table itself as read-only.
# In X64 build, it cannot be enabled at the same time with SMM profile feature (PcdCpuSmmProfileEnable).
# In X64 build, it could not be enabled also at the same time with heap guard feature for SMM
# (PcdHeapGuardPropertyMask in MdeModulePkg).
# In IA32 build, page table memory is not marked as read-only when either SMM profile feature (PcdCpuSmmProfileEnable)
# or heap guard feature for SMM (PcdHeapGuardPropertyMask in MdeModulePkg) is enabled.
# TRUE - Access to non-SMRAM memory is restricted to reserved, runtime and ACPI NVS type after SmmReadyToLock.<BR>
# FALSE - Access to any type of non-SMRAM memory after SmmReadyToLock is allowed.<BR>
# @Prompt Access to non-SMRAM memory is restricted to reserved, runtime and ACPI NVS type after SmmReadyToLock.