Messages in this thread | | | Date | Wed, 7 Dec 2016 13:36:45 +0000 | From | Matt Fleming <> | Subject | Re: [PATCH 4/4] efi: Skip parsing of EFI_PROPERTIES_TABLE if EFI_MEMORY_ATTRIBUTES_TABLE is detected |
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On Tue, 06 Dec, at 11:16:03AM, Sai Praneeth Prakhya wrote: > From: Sai Praneeth <sai.praneeth.prakhya@intel.com> > > UEFI specification v2.6 recommends not to use > "EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA" > attribute of EFI_PROPERTIES_TABLE. Presently, this is the *only* bit > defined in EFI_PROPERTIES_TABLE. This bit implies that EFI Runtime code > and data regions of an executable image are separate and are aligned as > specified in spec. Please refer to "EFI_PROPERTIES_TABLE" in section 4.6 > of UEFI specification v2.6 for more information on this table. > > UEFI v2.6 introduces EFI_MEMORY_ATTRIBUTES_TABLE and is intended to > replace EFI_PROPERTIES_TABLE. If EFI_MEMORY_ATTRIBUTES_TABLE is found we > skip updating of efi runtime region mappings based on > EFI_PROPERTIES_TABLE, so let's also skip parsing of EFI_PROPERTIES_TABLE > if we find EFI_MEMORY_ATTRIBUTES_TABLE because we are not using this > table anyways. The only caveat here is, if further versions of UEFI spec > adds some more bits (hence some more attributes) to EFI_PROPERTIES_TABLE > then we might need to parse it again, otherwise there is no good in > doing that. We can also expect that the same attributes might be reflected in > EFI_MEMORY_ATTRIBUTES_TABLE and hence saving us from parsing > EFI_PROPERTIES_TABLE again. > > Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com> > Cc: Lee, Chun-Yi <jlee@suse.com> > Cc: Borislav Petkov <bp@alien8.de> > Cc: Ricardo Neri <ricardo.neri@intel.com> > Cc: Matt Fleming <matt@codeblueprint.co.uk> > Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> > Cc: Ravi Shankar <ravi.v.shankar@intel.com> > Cc: Fenghua Yu <fenghua.yu@intel.com> > --- > drivers/firmware/efi/efi.c | 11 +++++++++++ > 1 file changed, 11 insertions(+)
I see where you're coming from with this patch, but I think it's unnecessary. Turning on/off parsing of Table A based on existence of Table B just seems like extra work.
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