Re: [PATCH 1/7] x86/fpu: Document signal frame layout and portability

[Borislav Petkov]

On Tue, Sep 08, 2026 at 04:34:21AM +0000, Andrei Vagin wrote:
> The x86 signal frame is designed to be self-describing, with the
> 'xstate_size' field in the software-reserved bytes indicating the actual
> size of the context. This design is required for portability, allowing a
> signal frame created on a system with a specific set of xstate features
> to be restored on a machine with a different (larger) set of features.
> 
> Document the signal frame software reserved bytes (struct _fpx_sw_bytes)
> and portability constraints in Documentation/arch/x86/xstate.rst, and
> add a summary and cross-reference in <uapi/asm/sigcontext.h>.
> 
> Reviewed-by: Alexander Mikhalitsyn <alexander@xxxxxxxxxxxxx>
> Signed-off-by: Andrei Vagin <avagin@xxxxxxxxxx>
> ---
>  Documentation/arch/x86/xstate.rst      | 55 ++++++++++++++++++++++++++
>  arch/x86/include/uapi/asm/sigcontext.h | 14 +++++++
>  2 files changed, 69 insertions(+)

Sashiko has some comments here:

https://sashiko.dev/#/patchset/20260908043427.1842515-1-avagin%40google.com

Please address them.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette