Re: [PATCH RFC] x86: remove toolchain check for X32 ABI capability

From: Nathan Chancellor <nathan@kernel.org>
To: Masahiro Yamada <masahiroy@kernel.org>
Cc: X86 ML <x86@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>, "H . Peter Anvin" <hpa@zytor.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Fangrui Song <maskray@google.com>,
	clang-built-linux <clang-built-linux@googlegroups.com>,
	"H . J . Lu" <hjl.tools@gmail.com>,
	Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	Brian Gerst <brgerst@gmail.com>,
	"Chang S. Bae" <chang.seok.bae@intel.com>,
	Chao Yu <chao@kernel.org>, "Darrick J. Wong" <djwong@kernel.org>,
	Dmitry Safonov <0x7f454c46@gmail.com>,
	Dominik Brodowski <linux@dominikbrodowski.net>,
	Gabriel Krisman Bertazi <krisman@collabora.com>,
	Ingo Molnar <mingo@redhat.com>, Jaroslav Kysela <perex@perex.cz>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	Jethro Beekman <jethro@fortanix.com>,
	Kees Cook <keescook@chromium.org>,
	Miklos Szeredi <miklos@szeredi.hu>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Sasha Levin <sashal@kernel.org>,
	Sean Christopherson <seanjc@google.com>,
	Takashi Iwai <tiwai@suse.com>,
	ALSA Development Mailing List <alsa-devel@alsa-project.org>,
	Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-xfs <linux-xfs@vger.kernel.org>
Subject: Re: [PATCH RFC] x86: remove toolchain check for X32 ABI capability
Date: Tue, 8 Jun 2021 10:26:30 -0700	[thread overview]
Message-ID: <1992c9cf-739e-d98f-85c0-bbcf7df123ea@kernel.org> (raw)
In-Reply-To: <CAK7LNASY_+_38XEMLZAf7txr4EdukkcFL8pnGGe2XyhQ9F4oDQ@mail.gmail.com>

Hi Masahiro,

On 6/7/2021 12:39 AM, Masahiro Yamada wrote:
> On Sun, Feb 28, 2021 at 3:49 PM Nathan Chancellor <nathan@kernel.org> wrote:
>>
>> On Sun, Feb 28, 2021 at 12:15:16PM +0900, Masahiro Yamada wrote:
>>> On Sun, Feb 28, 2021 at 3:41 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
>>>>
>>>> This commit reverts 0bf6276392e9 ("x32: Warn and disable rather than
>>>> error if binutils too old").
>>>>
>>>> The help text in arch/x86/Kconfig says enabling the X32 ABI support
>>>> needs binutils 2.22 or later. This is met because the minimal binutils
>>>> version is 2.23 according to Documentation/process/changes.rst.
>>>>
>>>> I would not say I am not familiar with toolchain configuration, but
>>>
>>> I mean:
>>> I would not say I am familiar ...
>>> That is why I added RFC.
>>>
>>> I appreciate comments from people who are familiar
>>> with toolchains (binutils, llvm).
>>>
>>> If this change is not safe,
>>> we can move this check to Kconfig at least.
>>
>> Hi Masahiro,
>>
>> As Fangrui pointed out, there are two outstanding issues with x32 with
>> LLVM=1, both seemingly related to LLVM=1.
> 
> Is this still a problem for Clang built Linux?
> 
> 
> 
>> https://github.com/ClangBuiltLinux/linux/issues/514
> 
> I am not tracking the status.
> What was the conclusion?

This appears to no longer be reproducible so I closed it.

>> https://github.com/ClangBuiltLinux/linux/issues/1141
> 
> 
> This got marked "unreproducible"

I just had a look at this and it is still reproducible (see the bug for 
details).

>> Additionally, there appears to be one from Arnd as well but that one has
>> received no triage yet.
>>
>> https://github.com/ClangBuiltLinux/linux/issues/1205
> 
> Same as well.

Yeah, I cannot reproduce this.

It seems like a Kconfig test would still be best for the issue above, if 
it is not too much to maintain.

Cheers,
Nathan