linux-kernel - Re: `KSYM_NAME

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Message-ID: <470357d7-5958-4470-a718-25b9c7660565@nvidia.com>
Date: Sun, 30 Nov 2025 20:56:29 -0800
From: John Hubbard <jhubbard@...dia.com>
To: Miguel Ojeda <ojeda@...nel.org>, Nathan Chancellor <nathan@...nel.org>,
 Nicolas Schier <nicolas@...sle.eu>
Cc: linux-kbuild@...r.kernel.org, Boqun Feng <boqun.feng@...il.com>,
 Gary Guo <gary@...yguo.net>, Björn Roy Baron
 <bjorn3_gh@...tonmail.com>, Benno Lossin <lossin@...nel.org>,
 Andreas Hindborg <a.hindborg@...nel.org>, Alice Ryhl <aliceryhl@...gle.com>,
 Trevor Gross <tmgross@...ch.edu>, Danilo Krummrich <dakr@...nel.org>,
 Sergio González Collado <sergio.collado@...il.com>,
 rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org,
 patches@...ts.linux.dev
Subject: Re: `KSYM_NAME_LEN` strikes again

On 11/30/25 6:16 PM, Miguel Ojeda wrote:
> Hi all,
> 
> In some Rust configs with -Os and doctests enabled, we are hitting
> KSYM_NAME_LEN again:
...
> Other options:
> 
>    - Conditionally doing it only for those builds that need it, to avoid
>      penalizing other builds (including normal Rust builds).
> 
>    - Building the Rust side with -O2 for now, or at least tweaking some
>      of the inlining behavior under -Os.
> 
>    - Not supporting Rust for `CC_OPTIMIZE_FOR_SIZE` for now (e.g. under
>      `BROKEN`).
> 
>    - Stop all this and go with a hashing approach like Willy/Linus
>      discussed back then:
> 
>          https://lore.kernel.org/rust-for-linux/CAHk-=whzXv=Fu7dQshSTyd9H1-JS5=gyKwW-GMNGccAKs4Mwpg@mail.gmail.com/
  
I'm impressed that you listed this last one, because it seems like a
somewhat extensive project!

But if it's actually an option, it seems like a very nice one:
a durable and long-lasting fix.

Maybe we would also get demangled backtraces at runtime as a side
effect, which would remove another minor bit of unhappiness too.
  

thanks,
-- 
John Hubbard