Re: [PATCH 0/4 v4] exec: inherit HWCAPs from the parent process

[Andrei Vagin <avagin@gmail.com>]

On Tue, Feb 17, 2026 at 10:01 AM Andrei Vagin <avagin@google.com> wrote:
>
> This patch series introduces a mechanism to inherit hardware capabilities
> (AT_HWCAP, AT_HWCAP2, etc.) from a parent process when they have been
> modified via prctl.
>
> To support C/R operations (snapshots, live migration) in heterogeneous
> clusters, we must ensure that processes utilize CPU features available
> on all potential target nodes. To solve this, we need to advertise a
> common feature set across the cluster.
>
> Initially, a cgroup-based approach was considered, but it was decided
> that inheriting HWCAPs from a parent process that has set its own
> auxiliary vector via prctl is a simpler and more flexible solution.
>
> This implementation adds a new mm flag MMF_USER_HWCAP, which is set when the
> auxiliary vector is modified via prctl(PR_SET_MM_AUXV). When execve() is
> called, if the current process has MMF_USER_HWCAP set, the HWCAP values are
> extracted from the current auxiliary vector and inherited by the new process.
>
> The first patch fixes AUXV size calculation for ELF_HWCAP3 and ELF_HWCAP4
> in binfmt_elf_fdpic and updates AT_VECTOR_SIZE_BASE.
>
> The second patch implements the core inheritance logic in execve().
>
> The third patch adds a selftest to verify that HWCAPs are correctly
> inherited across execve().
>
> v4: minor fixes based on feedback from the previous version.

Kees,

I think it is ready to be merged. Let me know if you have any other
comments/concerns/questions.

Thanks,
Andrei