Due to the introduction of NULL pointer detection feature, page 0 will be
disabled if the feature is enabled, which will cause legacy code failed to
update legacy data in page 0.
To avoid page fault caused by above feature in legacy code, legacy related
drivers have to enable page 0 temporarily before accessing page 0 and disable
it afterwards.
Old GCD servie has a bug which paging related attributes are not awared and
managed by GCD service. The legacy code has to use PCD
PcdNullPointerDetectionPropertyMask to know if page 0 is disabled or not.
As a result, two methods
EnableNullDetection()
DisableNullDetection()
were introduced to do enable/disable job just mentioned.
But the newly added PcdNullPointerDetectionPropertyMask caused backward
compatibility issue in some packages having legcy drivers. Since the
attributes missing issue in GCD services has been fixed, it's now able to
eliminate the dependency on this PCD.
Jian J Wang (3):
IntelFrameworkPkg/LegacyBios.h: Add a macro to guarantee page 0 access
IntelFrameworkModulePkg/LegacyBiosDxe: Use macro to enable/disable
page 0
IntelFrameworkModulePkg/KeyboardDxe: Use macro to enable/disable page
0
.../Csm/BiosThunk/KeyboardDxe/BiosKeyboard.c | 118 ++----------------
.../Csm/BiosThunk/KeyboardDxe/KeyboardDxe.inf | 1 -
.../Csm/LegacyBiosDxe/LegacyBda.c | 53 ++++----
.../Csm/LegacyBiosDxe/LegacyBios.c | 135 ++-------------------
.../Csm/LegacyBiosDxe/LegacyBiosDxe.inf | 1 -
.../Csm/LegacyBiosDxe/LegacyBiosInterface.h | 16 ---
.../Csm/LegacyBiosDxe/LegacyBootSupport.c | 80 ++++++------
.../Csm/LegacyBiosDxe/LegacyPci.c | 72 ++++++-----
IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c | 51 ++++----
IntelFrameworkPkg/Include/Protocol/LegacyBios.h | 34 ++++++
10 files changed, 179 insertions(+), 382 deletions(-)
--
2.15.1.windows.2
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