Re: [PATCH v5 02/24] x86/elf, um/x86/elf: Move relocation constants to UAPI

[H. Peter Anvin]

On September 9, 2026 7:49:30 AM PDT, Borislav Petkov <bp@xxxxxxxxx> wrote:
>On Wed, Sep 09, 2026 at 07:59:51AM +0200, Thomas Weißschuh wrote:
>> These names and numbers are defined by the architectures' ELF specifications.
>> They are already cast in stone. For example see Table 4.9 of [0].
>> Changing them would break compilers, linkers, loaders and more or less every
>> existing ELF binary.
>
>So?
>
>Your goal is to provide them to tools/. You want to provide them to
>*everything*. See the discrepance here?
>
>> That is the documentation for the tools UAPI headers.
>
>Did you even read that file?
>
>"Why we want a copy of kernel headers in tools?
>==============================================
>
>There used to be no copies, with tools/ code using kernel headers
>directly. From time to time tools/perf/ broke due to legitimate kernel
>hacking. At some point Linus complained about such direct usage. Then we
>adopted the current model.
>
>The way these headers are used in perf are not restricted to just
>including them to compile something.
>..."
>
>Just read the damn thing before you reply.
>
>> Also we already have other, closely related, ELF constants in the UAPI,
>> see {,tools/}include/uapi/linux/elf{,-em}.h.
>
>Srsly?!?
>
>You moved them there:
>
>commit 626fd35278295fbb21f2da331cd8028e9738d965
>Author: Thomas Weißschuh <thomas.weissschuh@xxxxxxxxxxxxx>
>Date:   Wed Feb 26 12:44:46 2025 +0100
>
>    tools/include: Add uapi/linux/elf.h
>    
>    It will be used by the vDSO selftests.
>
>
>Looking at the rest, it looks like some elf bits got exported, you added some
>more and that ship has sailed. I still think us providing headers is
>completely unnecessary and it will come to cause conflicts eventually but hey,
>not my problem.
>

I do believe there are *some* headers that would be reasonably to export to tools/ beyond what it is in uapi; a major reason for that is that the tools are suffering from a crazy level of internal inconsistency right now. 

Basically uapi ⊂ treewide ⊂ kernel, but also treewide ⊂ tools common ⊂ tool-specific...