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Date: Tue, 27 Feb 2024 10:53:35 +0000
From: Conor Dooley <conor.dooley@microchip.com>
To: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
CC: Conor Dooley <conor@kernel.org>, Matthew Maurer <mmaurer@google.com>,
	<linux-riscv@lists.infradead.org>, Miguel Ojeda <ojeda@kernel.org>, Alex
 Gaynor <alex.gaynor@gmail.com>, Wedson Almeida Filho <wedsonaf@gmail.com>,
	Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
	=?iso-8859-1?Q?Bj=F6rn?= Roy Baron <bjorn3_gh@protonmail.com>, Jonathan
 Corbet <corbet@lwn.net>, Paul Walmsley <paul.walmsley@sifive.com>, Palmer
 Dabbelt <palmer@dabbelt.com>, Nathan Chancellor <nathan@kernel.org>, Nick
 Desaulniers <ndesaulniers@google.com>, Tom Rix <trix@redhat.com>,
	<rust-for-linux@vger.kernel.org>, <linux-doc@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <llvm@lists.linux.dev>,
	<stable@vger.kernel.org>, Sami Tolvanen <samitolvanen@google.com>, Ramon de C
 Valle <rcvalle@google.com>
Subject: Re: [PATCH v2 1/3] rust: make mutually exclusive with CFI_CLANG
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On Fri, Feb 23, 2024 at 03:45:10PM +0100, Miguel Ojeda wrote:
> On Fri, Feb 23, 2024 at 2:38=E2=80=AFPM Conor Dooley <conor@kernel.org> w=
rote:
> >
> > configuring a kernel without symmetrical support for kfi.
>=20
> Nit: typo.
>=20
> > This probably needs to go to stable. The correct fixes tag for that I am
> > not sure of however, but since CFI_CLANG predates RUST, I blamed the
> > commit adding rust support.
>=20
> Cc'ing Matthew et al. in case this is a problem for them, but I guess
> we can relax it later as needed.

I suspect that nobody has actually sat down and tried it.

I did try to test it but I ran into too many toolchain issues - my
older copies of LLVM (pre 17) are not multiarch as I built them by hand
with PGO for x86 and RISC-V. My LLVM 17 is from kernel.org and has no
libclang. And then the copy of LLVM 18 on kernel.org apparently does not
support kcfi at all. I gave up there, but I don't see how this would not
be a problem on other arches, given rustc never gets told to enable
kcfi.

Cheers,
Conor.

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