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From:   Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Date:   Fri, 8 Dec 2023 18:37:50 +0100
Message-ID: <CANiq72nkXu1esMjK-DF3iCw93YfRzRCaFWZxr5emZthnvVr+zg@mail.gmail.com>
Subject: Re: [PATCH 5/7] rust: file: add `Kuid` wrapper
To:     Nick Desaulniers <ndesaulniers@google.com>
Cc:     comex <comexk@gmail.com>, Christian Brauner <brauner@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Alice Ryhl <aliceryhl@google.com>,
        Miguel Ojeda <ojeda@kernel.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
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        Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
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On Fri, Dec 8, 2023 at 6:09=E2=80=AFPM Nick Desaulniers <ndesaulniers@googl=
e.com> wrote:
>
> On paper, nothing comes to mind.  No promises though.

Thanks Nick -- that is useful nevertheless.

> From a build system perspective, I'd rather just point users towards
> LTO if they have this concern.  We support full and thin lto.  This
> proposal would add a third variant for just rust drivers.  Each
> variation on LTO has a maintenance cost and each have had their own
> distinct fun bugs in the past.  Not sure an additional variant is
> worth the maintenance cost, even if it's technically feasible.

I was thinking it would be something always done for Rust object
files: under a normal "no LTO" build, the Rust object files would
always get the cross-language inlining done and therefore no extra
dimension in the matrix. Would that help?

I think it is worth at least considering, given there is also a
non-trivial amount of performance to gain if we always do it, e.g.
Andreas wanted it for non-LTO kernel for this reason.

Cheers,
Miguel