> On Aug 14, 2023, at 21:38, Frank Scheiner <frank.schei...@web.de> wrote: > > Hi Steffen, Ard, > >> On 14.08.23 21:59, Oliver Steffen wrote: >> Quoting Vladimir 'phcoder' Serbinenko (2023-08-13 09:46:45) >>> Full analysis: gpt_partentry can be marked as aligned8. But following are >>> problem: >>> * protocols_per_handle may return unaligned guids >>> * configuration_tables array may be unaligned. On efi32 every entry is 20 >>> bytes, so guids can't be 8-byte aligned >>> * The worst offender is device path as it's packed, unpredictable and >>> contains >>> uuids. >>> * Efiemu gets guid as argument and probably should be able to handle >>> unaligned >>> case. So far it's x86 only and we have no mmx and co so it's not a problem >>> right now unless we enable ubsan. >>> All in all we do need packed guid type unless those are resolved. I attach >>> patches for testing. If they work, I'll rearrange them a bit >> >> Looking at https://uefi.org/specs/UEFI/2.10/02_Overview.html#data-types, >> the problem is the alignment, not the packing. >> >> As far as EFI is concerned, GUIDs are always 128bit in size. This means >> there shall be no padding between the struct members. To be on the safe >> side one could add the "packed" attribute to the struct, but the >> original grub_efi_guid struct was not marked like that and it worked. >> Whenever we had over GUIDs to EFI, they have to be aligned to 64bit. > > Ard thinks that a 64 bit alignment for EFI GUIDs is a mistake - see [1] > and [2]. Hence Linux uses `__aligned(__alignof__(u32))` for "efi_guid_t" > since 2019. > > [1]: > https://github.com/torvalds/linux/blob/master/include/linux/efi.h#L60-L78 > > [2]: > https://github.com/torvalds/linux/commit/494c704f9af0a0cddf593b381ea44320888733e6 > > I know I mentioned [1] earlier, but it sounds like it might have slipped > through and it might be a good idea to have both GRUB and Linux in sync > in this regard. >
So what is GRUB's current allocation granule, if it is not the same as Linux? > Cheers, > Frank _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
