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AJvYcCVXDXBniPgGycDKA6vQR68RpZtVJKxm4IfXWO4DBHDPjEIrwmjXSWiuHsrGQCo6ktd6tjE53GOvJ9GwC12gYA==@vger.kernel.org X-Gm-Message-State: AOJu0YzMN8CbS82+dMmEhb5SYdcHQdxqU1rKJoWH/ZaYWLf+F7KfjVTO Puz59zEL5tQOvJspYEuC7ySGDTf4fkuKvpuGxxDCOjIJZAYFea7l8vUV0P9Ue6yoq9vxBGB/hue l7nuZqykfmeSmUW+rBQ== X-Received: from wmna22.prod.google.com ([2002:a05:600c:696:b0:483:272e:764f]) (user=aliceryhl job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:3e8e:b0:47a:8cce:2940 with SMTP id 5b1f17b1804b1-483c9ba2922mr208928775e9.14.1772436565594; Sun, 01 Mar 2026 23:29:25 -0800 (PST) Date: Mon, 2 Mar 2026 07:29:24 +0000 In-Reply-To: Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260210090023.2587534-1-mkchauras@gmail.com> <20260210090023.2587534-3-mkchauras@gmail.com> <0a176f95-eeba-428e-b19b-b08503d9ca5d@ralfj.de> Message-ID: Subject: Re: [PATCH V6 2/3] rust: Add PowerPC support From: Alice Ryhl To: Mukesh Kumar Chaurasiya Cc: Ralf Jung , Miguel Ojeda , Link Mauve , ojeda@kernel.org, boqun.feng@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, lossin@kernel.org, a.hindborg@kernel.org, tmgross@umich.edu, dakr@kernel.org, corbet@lwn.net, maddy@linux.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, chleroy@kernel.org, peterz@infradead.org, jpoimboe@kernel.org, jbaron@akamai.com, rostedt@goodmis.org, ardb@kernel.org, rust-for-linux@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Jubilee Young , Matthew Maurer , David Wood , Wesley Wiser Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable On Mon, Mar 02, 2026 at 11:25:54AM +0530, Mukesh Kumar Chaurasiya wrote: > On Tue, Feb 24, 2026 at 09:58:10AM +0100, Ralf Jung wrote: > > Hi all, > >=20 > > On 23.02.26 16:31, Miguel Ojeda wrote: > > > On Mon, Feb 23, 2026 at 3:26=E2=80=AFAM Mukesh Kumar Chaurasiya > > > wrote: > > > >=20 > > > > I think, disabling altivec, fpu and vsx with compiler flag will wor= k. > > > >=20 > > > > What are your opinion on this? > > >=20 > > > It is really up to upstream Rust -- for us, i.e. the kernel, it > > > usually doesn't really matter much how things like that are > > > accomplished: whether via flags, a built-in target, a custom target, > > > etc. However, we need to know what the path to stability is. > > >=20 > > > My understanding (but I may be wrong) is that upstream Rust prefer we > > > use built-in targets for softfloat instead of disabling via > > > `-Ctarget-feature` (and that the other options may go away soon and/o= r > > > will never be stable) -- at least for some cases. For instance, for > > > arm64, please this recent change kernel-side regarding `neon` as an > > > entry point: > > >=20 > > > 446a8351f160 ("arm64: rust: clean Rust 1.85.0 warning using softfl= oat target") > > >=20 > > > So please ask upstream Rust (probably in their Zulip, e.g. in > > > t-compiler or rust-for-linux channels) what you should do for powerpc= . > > > They will likely be happy with a PR adding the target (or whatever > > > they decide) as Alice mentions. And until we reach that minimum > > > version (in a year or more), we can use something else meanwhile. But > > > at least we will have a way towards the end goal, if that makes sense= . > > >=20 > > > In case it helps, let me Cc Ralf, Jubilee and Matthew who were > > > involved in some of that discussion in the past, plus the compiler > > > leads. > >=20 > > Upstream Rust dev here. Indeed we'd strongly prefer if this could use a > > built-in Rust target; we can work with you on adding a new target if th= at is > > needed. > > The kernel currently uses a custom JSON target on x86 and that's quite = the > > headache for compiler development: JSON targets are highly unstable and > > directly expose low-level details of how the compiler internally repres= ents > > targets. When we change that representation, we update all built-in tar= gets, > > but of course we cannot update JSON targets. So whenever possible we'd = like > > to move towards reducing the number of JSON targets used by the kernel,= not > > increase it. :) > >=20 > > Kind regards, > > Ralf > >=20 > Hey, >=20 > Sorry for delayed response. I was out of network zone. >=20 > I am not sure about the process of how to get this in rust toolchain. > Should I raise an issue of github for this? You would need to add a new file to compiler/rustc_target/src/spec/targets in the rustc repository. If you're not sure what to put there, I would suggest coming up with something that looks plausible, and opening a PR with that. Then others can help you with filling out the target correctly. Alice