Ard, EFI_MEMORY_WP is for cache.
UefiSpec.h // // Note: UEFI spec 2.5 and following: use EFI_MEMORY_RO as write-protected physical memory // protection attribute. Also, EFI_MEMORY_WP means cacheability attribute. // #define EFI_MEMORY_WP 0x0000000000001000ULL Thanks, Star -----Original Message----- From: Ard Biesheuvel [mailto:ard.biesheu...@linaro.org] Sent: Thursday, November 16, 2017 5:25 PM To: Wang, Jian J <jian.j.w...@intel.com> Cc: edk2-devel@lists.01.org; Yao, Jiewen <jiewen....@intel.com>; Zeng, Star <star.z...@intel.com>; Laszlo Ersek <ler...@redhat.com> Subject: Re: [PATCH v6 1/2] MdeModulePkg/DxeCore: Filter out all paging capabilities On 16 November 2017 at 07:26, Jian J Wang <jian.j.w...@intel.com> wrote: > Some OSs will treat EFI_MEMORY_DESCRIPTOR.Attribute as really set > attributes and change memory paging attribute accordingly. > But current EFI_MEMORY_DESCRIPTOR.Attribute is assigned by value from > Capabilities in GCD memory map. This might cause boot problems. > Clearing all paging related capabilities can workaround it. The code > added in this patch is supposed to be removed once the usage of > EFI_MEMORY_DESCRIPTOR.Attribute is clarified in UEFI spec and adopted > by both EDK-II Core and all supported OSs. > > Cc: Jiewen Yao <jiewen....@intel.com> > Cc: Star Zeng <star.z...@intel.com> > Cc: Laszlo Ersek <ler...@redhat.com> > Cc: Ard Biesheuvel <ard.biesheu...@linaro.org> > Contributed-under: TianoCore Contribution Agreement 1.1 > Signed-off-by: Jian J Wang <jian.j.w...@intel.com> > --- > MdeModulePkg/Core/Dxe/Mem/Page.c | 17 +++++++++++++++++ > 1 file changed, 17 insertions(+) > > diff --git a/MdeModulePkg/Core/Dxe/Mem/Page.c > b/MdeModulePkg/Core/Dxe/Mem/Page.c > index c9219cc068..783b576e35 100644 > --- a/MdeModulePkg/Core/Dxe/Mem/Page.c > +++ b/MdeModulePkg/Core/Dxe/Mem/Page.c > @@ -1829,6 +1829,23 @@ CoreGetMemoryMap ( > // > BufferSize = ((UINT8 *)MemoryMap - (UINT8 *)MemoryMapStart); > > + // > + // WORKAROUND: Some OSs will treat EFI_MEMORY_DESCRIPTOR.Attribute as > really > + // set attributes and change memory paging attribute > accordingly. > + // But current EFI_MEMORY_DESCRIPTOR.Attribute is assigned by > + // value from Capabilities in GCD memory map. This might cause > + // boot problems. Clearing all paging related capabilities can > + // workaround it. Following code is supposed to be removed once > + // the usage of EFI_MEMORY_DESCRIPTOR.Attribute is clarified in > + // UEFI spec and adopted by both EDK-II Core and all supported > + // OSs. > + // > + while (MemoryMapStart < MemoryMap) { > + MemoryMapStart->Attribute &= ~(UINT64)(EFI_MEMORY_RP | EFI_MEMORY_RO | > + EFI_MEMORY_XP); Why is EFI_MEMORY_WP missing here? > + MemoryMapStart = NEXT_MEMORY_DESCRIPTOR(MemoryMapStart, Size); } > + > Status = EFI_SUCCESS; > > Done: > -- > 2.14.1.windows.1 > _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
