Re: [PATCH 0/4] Rust for Linux for ppc64le

From: Michael Ellerman <mpe@ellerman.id.au>
To: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc: rust-for-linux@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/4] Rust for Linux for ppc64le
Date: Tue, 23 Mar 2021 23:15:50 +1100	[thread overview]
Message-ID: <87mtuugj61.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <CANiq72n-tMww2U+eQ=iHOh5u1JQgjM0b1E3XQ9jpWMfpdQ5+=g@mail.gmail.com>

Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> writes:
> Hi Michael,
>
> On Tue, Mar 23, 2021 at 4:27 AM Michael Ellerman <mpe@ellerman.id.au> wrote:
>>
>> Hi all,
>>
>> Here's a first attempt at getting the kernel Rust support building on powerpc.
>
> Thanks a *lot*! It is great to have more architectures rolling.

No worries.

>> It's powerpc64le only for now, as that's what I can easily test given the
>> distros I have installed. Though powerpc and powerpc64 are also Tier 2 platforms
>
> Even if it is just 64-bit, it is very good to have it!
>
>> so in theory should work. Supporting those would require something more
>> complicated than just pointing rustc at arch/$(ARCH)/rust/target.json.
>
> Yeah, the arch/$(ARCH)/rust/target.json dance is a placeholder -- I
> need to figure out how to do that more cleanly, likely generating them
> on the fly.

Yeah that's a good idea. That way they can be made to exactly match the
kernel configuration.

>> This is based on 832575d934a2 from the Rust-for-Linux tree. Anything newer gives
>> me errors about symbol name lengths. I figured I'd send this anyway, as it seems
>> like those errors are probably not powerpc specific.
>
> Sure, feel free to send things even if they don't work completely.
>
> I will take a look at the symbol name lengths -- I increased that
> limit to 512 and added support for 2-byte lengths in the tables, but
> perhaps something is missing. If I manage to make it work, I can add
> ppc64le to our CI! :-)

It would be nice to be in the CI. I was building natively so I haven't
tried cross compiling yet (which we'll need for CI).

>> Michael Ellerman (4):
>>   rust: Export symbols in initialized data section
>>   rust: Add powerpc64 as a 64-bit target_arch in c_types.rs
>>   powerpc/rust: Add target.json for ppc64le
>>   rust: Enable for ppc64le
>
> Regarding the development process: at least until the RFC we are
> working with the usual GitHub PR workflow (for several reasons: having
> a quick CI setup, getting new Rust developers on-board, having a list
> of "issues", cross-reference with the Rust repo, etc.).
>
> I can take patches from the list, of course, but since we are pre-RFC,
> do you mind if they get rebased etc. through there?

No I don't mind at all. I just sent patches so other ppc folks could see
what I had, and it's kind of the process I'm used to.

I can send a pull request if that's easiest.

cheers