On 23.06.2025 22:18, Andrew Cooper wrote:
> On 16/06/2025 7:27 am, Jan Beulich wrote:
>> To expand on my earlier suggestion (ab)using the "efi" global: With
>> the linker script having this
>>
>> #ifdef EFI
>> .reloc ALIGN(4) : {
>> __base_relocs_start = .;
>> *(.reloc)
>> __base_relocs_end = .;
>> }
>> #elif defined(XEN_BUILD_EFI)
>> /*
>> * Due to the way EFI support is currently implemented, these two symbols
>> * need to be defined. Their precise values shouldn't matter (the
>> consuming
>> * function doesn't get called), but to be on the safe side both values
>> would
>> * better match. Of course the need to be reachable by the relocations
>> * referencing them.
>> */
>> PROVIDE(__base_relocs_start = .);
>> PROVIDE(__base_relocs_end = .);
>> #else
>> efi = .;
>> #endif
>>
>> where only the #if applies to xen.efi, can't we (ab)use the combination of
>> the
>> other two symbols here to decide between xen.efi vs xen.gz?
>> __base_relocs_{start,efi} won't possibly be equal for xen.efi, except in an
>> extremely theoretical situation (and we could cover for that case by an
>> ASSERT
>> in the linker script). Pseudo code:
>>
>> #ifdef XEN_BUILD_EFI
>> if ( __base_relocs_start != __base_relocs_end )
>> {
>> ...
>> }
>> #endif
>>
>> IOW that #if could simply replace the CONFIG_X86 one that's there right now.
>
> That's horrifying. Also you can't include efi-boot.h to get the
> declarations.
The declarations could be moved, but ...
> But given that you are adamant that the (...) in there containing a
> CodeView check is unacceptable to have, why does wrapping it in yet
> another conditional make it ok?
... hmm, yes, there'll still be unreachable code there. I guess I'll shut
up here and leave this to the EFI maintainers. Just as long as there's not
going to be any Eclair / Misra fallout.
Jan
