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From: Jamie Cunliffe <Jamie.Cunliffe@arm.com>
To: miguel.ojeda.sandonis@gmail.com
Cc: Jamie.Cunliffe@arm.com, catalin.marinas@arm.com,
	linux-arm-kernel@lists.infradead.org, ojeda@kernel.org,
	rust-for-linux@vger.kernel.org, steve.capper@arm.com,
	will@kernel.org
Subject: Re: [PATCH 1/3] arm64: rust: Enable Rust support for AArch64
Date: Tue, 18 Apr 2023 16:06:16 +0100	[thread overview]
Message-ID: <20230418150616.2247298-1-Jamie.Cunliffe@arm.com> (raw)
In-Reply-To: <CANiq72=cJPCLmbyAJhY3FEwMS4tonPtJspMG7Kb_EAEZ2CFwhg@mail.gmail.com>

On Tue, Jan 31, 2023 at 5:19 PM Will Deacon <will@kernel.org> wrote:
> On Thu, Jan 26, 2023 at 06:56:01PM +0100, Miguel Ojeda wrote:
> > On Thu, Jan 26, 2023 at 5:35 PM Will Deacon <will at kernel.org> wrote:
> > >
> > > Why do we need to specify this stuff here? LLVM already knows about AArch64
> > > and can compute the data-layout string in computeDataLayout(). Can we have
> > > the tools figure this out for us instead, please?
> > 
> > I agree -- the reason we have this for the moment is to provide full
> > control of the target spec, in particular for cases where `rustc` may
> > not provide enough flags to customize exiting builtin target specs
> > and/or may emit warnings for unknown target features etc.
> > 
> > If it is already enough for arm64 to use e.g. the
> > `aarch64-unknown-none` target spec plus flags on top, then we should
> > go for that, because that is the end goal: these target spec files are
> > unstable in the Rust compiler (and not intended to become stable).
> 
> Please confirm that this is the case, but I really think we should be
> aiming for that rather than starting off my specifying this stuff manually.

The json that we generate looks to be almost equivalent (that's why patch 3
exists, to answer your question on that patch). The only difference is the
`aarch64-unknown-none` rustc target sets the LLVM target to also be
`aarch64-unknown-none`, whereas the current target.json uses the
`aarch64-linux-gnu` LLVM target as does Makefile.clang for C code. As you have
been talking about the unknown-none target throughout this thread, I just wanted
to double check that's your intention?

Happy to switch over to using the rustc definition though. I just did it this
way to keep it consistent with the other architectures and not add any more
complexity into the build. On a quick test it does seem to be OK, but I'll
prepare a patch and do some proper testing that it's actually fine to use the
rustc definition though.

  reply	other threads:[~2023-04-18 15:07 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-25 16:37 [PATCH 0/3] Rust enablement for AArch64 Jamie Cunliffe
2023-01-25 16:37 ` [PATCH 1/3] arm64: rust: Enable Rust support " Jamie Cunliffe
2023-01-25 19:50   ` Vincenzo Palazzo
2023-01-25 19:56   ` Vincenzo Palazzo
2023-01-26 16:35   ` Will Deacon
2023-01-26 17:56     ` Miguel Ojeda
2023-01-31 16:19       ` Will Deacon
2023-01-31 16:49         ` Björn Roy Baron
2023-01-31 18:55         ` Miguel Ojeda
2023-04-18 15:06           ` Jamie Cunliffe [this message]
2023-01-27 14:09   ` Gary Guo
2023-05-02 13:41   ` Asahi Lina
2023-01-25 16:37 ` [PATCH 2/3] arm64: rust: Enable PAC support for Rust Jamie Cunliffe
2023-01-25 19:54   ` Vincenzo Palazzo
2023-01-25 16:37 ` [PATCH 3/3] arm64: rust: Disable neon and fp target features Jamie Cunliffe
2023-01-25 17:49   ` Miguel Ojeda
2023-01-25 19:55   ` Vincenzo Palazzo
2023-01-26 16:37   ` Will Deacon
2023-01-25 18:01 ` [PATCH 0/3] Rust enablement for AArch64 Miguel Ojeda
2023-03-07  9:32 ` Asahi Lina
2023-03-07 12:17   ` Miguel Ojeda

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