From: Nick Desaulniers <ndesaulniers@google.com>
To: Miguel Ojeda <ojeda@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org,
Jarkko Sakkinen <jarkko@kernel.org>,
Alex Gaynor <alex.gaynor@gmail.com>, Finn Behrens <me@kloenk.de>,
Adam Bratschi-Kaye <ark.email@gmail.com>,
Wedson Almeida Filho <wedsonaf@google.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Sven Van Asbroeck <thesven73@gmail.com>,
Gary Guo <gary@garyguo.net>,
Boris-Chengbiao Zhou <bobo1239@web.de>,
Boqun Feng <boqun.feng@gmail.com>,
Douglas Su <d0u9.su@outlook.com>,
Dariusz Sosnowski <dsosnowski@dsosnowski.pl>,
Antonio Terceiro <antonio.terceiro@linaro.org>,
Daniel Xu <dxu@dxuuu.xyz>, Miguel Cano <macanroj@gmail.com>,
David Gow <davidgow@google.com>,
Masahiro Yamada <masahiroy@kernel.org>,
Michal Marek <michal.lkml@markovi.net>,
Russell King <linux@armlinux.org.uk>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Richard Weinberger <richard@nod.at>,
Anton Ivanov <anton.ivanov@cambridgegreys.com>,
Johannes Berg <johannes@sipsolutions.net>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
linux-kbuild@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org,
linux-um@lists.infradead.org
Subject: Re: [PATCH v7 21/25] Kbuild: add Rust support
Date: Mon, 23 May 2022 11:44:51 -0700 [thread overview]
Message-ID: <CAKwvOdkTjxNEmCTnuH5f41WB50ef6ErBM2Kp2zJ-t9q_5U8rBA@mail.gmail.com> (raw)
In-Reply-To: <20220523020209.11810-22-ojeda@kernel.org>
> +choice
> + prompt "Optimization level"
> + default RUST_OPT_LEVEL_SIMILAR_AS_CHOSEN_FOR_C
> + depends on RUST
> + help
> + Controls rustc's `-Copt-level` codegen option.
> +
> + This flag controls the optimization level.
> +
> + If unsure, say "Similar as chosen for C".
> +
> +config RUST_OPT_LEVEL_SIMILAR_AS_CHOSEN_FOR_C
> + bool "Similar as chosen for C"
> + help
> + This choice will pick a similar optimization level as chosen in
> + the "Compiler optimization level" for C:
> +
> + -O2 is currently mapped to -Copt-level=2
> + -O3 is currently mapped to -Copt-level=3
> + -Os is currently mapped to -Copt-level=s
> +
> + The mapping may change over time to follow the intended semantics
> + of the choice for C as sensibly as possible.
> +
> + This is the default.
> +
> +config RUST_OPT_LEVEL_0
> + bool "No optimizations (-Copt-level=0)"
> + help
> + Not recommended for most purposes. It may come in handy for debugging
> + suspected optimizer bugs, unexpected undefined behavior, etc.
> +
> + Note that this level will *not* enable debug assertions nor overflow
> + checks on its own (like it happens when interacting with rustc
> + directly). Use the corresponding configuration options to control
> + that instead, orthogonally.
> +
> + Note this level may cause excessive stack usage, which can lead to stack
> + overflow and subsequent crashes.
> +
> +config RUST_OPT_LEVEL_1
> + bool "Basic optimizations (-Copt-level=1)"
> + help
> + Useful for debugging without getting too lost, but without
> + the overhead and boilerplate of no optimizations at all.
> +
> + Note this level may cause excessive stack usage, which can lead to stack
> + overflow and subsequent crashes.
> +
> +config RUST_OPT_LEVEL_2
> + bool "Some optimizations (-Copt-level=2)"
> + help
> + The sensible choice in most cases.
> +
> +config RUST_OPT_LEVEL_3
> + bool "All optimizations (-Copt-level=3)"
> + help
> + Yet more performance (hopefully).
> +
> +config RUST_OPT_LEVEL_S
> + bool "Optimize for size (-Copt-level=s)"
> + help
> + Smaller kernel, ideally without too much performance loss.
> +
> +config RUST_OPT_LEVEL_Z
> + bool "Optimize for size, no loop vectorization (-Copt-level=z)"
> + help
> + Like the previous level, but also turn off loop vectorization.
I'm super not into having the rust optimization level differ from the
C optimization level. This is just someone having too much fun
wrapping every compiler flag in a kbuild option. Either folks wan't
smaller size or more optimizations. Allowing for RUST_OPT_LEVEL_S and
CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE or RUST_OPT_LEVEL_3 and
CONFIG_CC_OPTIMIZE_FOR_SIZE is just wacky nonsense that's going to
make randconfig bug reports more confusing to tease out.
--
Thanks,
~Nick Desaulniers
next prev parent reply other threads:[~2022-05-23 19:09 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-23 2:01 [PATCH v7 00/25] Rust support Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 01/25] kallsyms: avoid hardcoding the buffer size Miguel Ojeda
2022-05-23 19:45 ` Jarkko Sakkinen
2022-05-23 19:55 ` Jarkko Sakkinen
2022-05-24 16:21 ` Miguel Ojeda
2022-05-26 4:54 ` Jarkko Sakkinen
2022-05-23 2:01 ` [PATCH v7 02/25] kallsyms: support "big" kernel symbols Miguel Ojeda
2022-05-23 20:30 ` Jarkko Sakkinen
2022-05-23 2:01 ` [PATCH v7 03/25] kallsyms: increase maximum kernel symbol length to 512 Miguel Ojeda
2022-05-23 20:31 ` Jarkko Sakkinen
2022-05-24 18:07 ` Miguel Ojeda
2022-05-27 16:25 ` Jarkko Sakkinen
2022-05-30 13:01 ` Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 04/25] kunit: take `kunit_assert` as `const` Miguel Ojeda
2022-05-23 17:15 ` Daniel Latypov
2022-05-23 18:14 ` Shuah Khan
2022-05-24 12:37 ` Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 05/25] rust: add C helpers Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 06/25] rust: add `compiler_builtins` crate Miguel Ojeda
2022-05-23 18:37 ` Nick Desaulniers
2022-05-23 23:41 ` Gary Guo
2022-05-25 21:29 ` Nick Desaulniers
2022-05-24 12:29 ` Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 07/25] rust: import upstream `alloc` crate Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 08/25] rust: adapt `alloc` crate to the kernel Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 09/25] rust: add `build_error` crate Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 10/25] rust: add `macros` crate Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 11/25] rust: add `kernel` crate's `sync` module Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 12/25] rust: add `kernel` crate Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 13/25] rust: export generated symbols Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 14/25] vsprintf: add new `%pA` format specifier Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 15/25] scripts: checkpatch: diagnose uses of `%pA` in the C side Miguel Ojeda
2022-05-23 2:17 ` Joe Perches
2022-05-24 16:35 ` Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 16/25] scripts: checkpatch: enable language-independent checks for Rust Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 17/25] scripts: add `rustdoc_test_{builder,gen}.py` scripts Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 18/25] scripts: add `generate_rust_analyzer.py` scripts Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 19/25] scripts: decode_stacktrace: demangle Rust symbols Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 20/25] docs: add Rust documentation Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 21/25] Kbuild: add Rust support Miguel Ojeda
2022-05-23 18:44 ` Nick Desaulniers [this message]
2022-05-24 15:12 ` Miguel Ojeda
2022-05-25 22:25 ` Nick Desaulniers
2022-05-30 13:39 ` Miguel Ojeda
2022-07-16 8:21 ` Masahiro Yamada
2022-07-16 8:57 ` Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 22/25] samples: add Rust examples Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 23/25] MAINTAINERS: Rust Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 24/25] [RFC] drivers: gpio: PrimeCell PL061 in Rust Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 25/25] [RFC] drivers: android: Binder IPC " Miguel Ojeda
2022-07-16 12:42 ` [PATCH v7 00/25] Rust support Conor Dooley
2022-07-16 13:36 ` Miguel Ojeda
2022-07-16 13:51 ` Conor.Dooley
2022-07-16 13:56 ` Miguel Ojeda
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAKwvOdkTjxNEmCTnuH5f41WB50ef6ErBM2Kp2zJ-t9q_5U8rBA@mail.gmail.com \
--to=ndesaulniers@google.com \
--cc=alex.gaynor@gmail.com \
--cc=anton.ivanov@cambridgegreys.com \
--cc=antonio.terceiro@linaro.org \
--cc=aou@eecs.berkeley.edu \
--cc=ark.email@gmail.com \
--cc=benh@kernel.crashing.org \
--cc=bobo1239@web.de \
--cc=boqun.feng@gmail.com \
--cc=bp@alien8.de \
--cc=catalin.marinas@arm.com \
--cc=d0u9.su@outlook.com \
--cc=dave.hansen@linux.intel.com \
--cc=davidgow@google.com \
--cc=dsosnowski@dsosnowski.pl \
--cc=dxu@dxuuu.xyz \
--cc=gary@garyguo.net \
--cc=gregkh@linuxfoundation.org \
--cc=hpa@zytor.com \
--cc=jarkko@kernel.org \
--cc=johannes@sipsolutions.net \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kbuild@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=linux-um@lists.infradead.org \
--cc=linux@armlinux.org.uk \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=macanroj@gmail.com \
--cc=masahiroy@kernel.org \
--cc=me@kloenk.de \
--cc=michal.lkml@markovi.net \
--cc=mingo@redhat.com \
--cc=mpe@ellerman.id.au \
--cc=ojeda@kernel.org \
--cc=palmer@dabbelt.com \
--cc=paul.walmsley@sifive.com \
--cc=paulus@samba.org \
--cc=richard@nod.at \
--cc=rust-for-linux@vger.kernel.org \
--cc=tglx@linutronix.de \
--cc=thesven73@gmail.com \
--cc=torvalds@linux-foundation.org \
--cc=wedsonaf@google.com \
--cc=will@kernel.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).