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 _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel