On Fri, 7 Apr 2023 at 04:46, AKASHI Takahiro <takahiro.aka...@linaro.org> wrote: > > Hi Ilias, > > On Thu, Apr 06, 2023 at 10:37:07PM +0300, Ilias Apalodimas wrote: > > Tom reports that when building with clang we see this warning: > > field guid within 'struct efi_hii_keyboard_layout' is less aligned than > > 'efi_guid_t' and is usually due to 'struct efi_hii_keyboard_layout' being > > packed, which can lead to unaligned accesses [-Wunaligned-access] > > > > This happens because 'struct efi_hii_keyboard_layout' is defined as > > packed while efi_guid_t is 32bit aligned. > > There are a couple of 'struct' definitions which are *packed* > and contain an 'efi_guid_t' member in efi_api.h. > If 'efi_hii_keyboard_layout' is the only place that causes a clang warning, > we need a more specific explanation to clarify the problem.
I assumed that all other definitions are aligned regardless of packed, i.e they are defined right after a u32, u64, 2xu16 etc, but I'll have a closer look > > > However the EFI spec describes the EFI_GUID as > > "128-bit buffer containing a unique identifier value. > > Unless otherwise specified aligned on a 64-bit boundary" > > That's right, but this text in this context may sound misleading. > (It doesn't explain why 'efi_guid_t' is 32-bit aligned.) commit 1dd705cf9903 ("efi: use 32-bit alignment for efi_guid_t") explains why, but it's a bit orthogonal to this commit. In any case I'll include it in v2 Thanks /Ilias > > -Takahiro Akashi > > > > > So convert the efi_guid_t -> u8 b[16] here and skip the alignment > > requirements. > > > > Reported-by: Tom Rini <tr...@konsulko.com> > > Suggested-by: Heinrich Schuchardt <heinrich.schucha...@canonical.com> > > Signed-off-by: Ilias Apalodimas <ilias.apalodi...@linaro.org> > > --- > > include/efi_api.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/include/efi_api.h b/include/efi_api.h > > index 2fd0221c1c77..b84b577bd7b5 100644 > > --- a/include/efi_api.h > > +++ b/include/efi_api.h > > @@ -1170,7 +1170,7 @@ struct efi_key_descriptor { > > > > struct efi_hii_keyboard_layout { > > u16 layout_length; > > - efi_guid_t guid; > > + u8 guid[16]; > > u32 layout_descriptor_string_offset; > > u8 descriptor_count; > > /* struct efi_key_descriptor descriptors[]; follows here */ > > -- > > 2.39.2 > >