Re: [PATCH v2] arm64: jump_label: use constraints "Si" instead of "i"

From: "Arnd Bergmann" <arnd@arndb.de>
To: "Ard Biesheuvel" <ardb@kernel.org>,
	"Geert Uytterhoeven" <geert@linux-m68k.org>
Cc: "Fangrui Song" <maskray@google.com>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	"Will Deacon" <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	"Jisheng Zhang" <jszhang@kernel.org>,
	"Dave Martin" <Dave.Martin@arm.com>,
	"Peter Smith" <peter.smith@arm.com>,
	llvm@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] arm64: jump_label: use constraints "Si" instead of "i"
Date: Mon, 19 Feb 2024 18:06:19 +0100	[thread overview]
Message-ID: <dca5b082-90d1-40ab-954f-8b3b6f51138c@app.fastmail.com> (raw)
In-Reply-To: <CAMj1kXHh_m=V0QsiTpHrUXpFBXFbFfezdysz8quhPSgUrZg1MA@mail.gmail.com>

On Mon, Feb 19, 2024, at 16:41, Ard Biesheuvel wrote:
> On Mon, 19 Feb 2024 at 15:43, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>> On Mon, Feb 19, 2024 at 11:57 AM Ard Biesheuvel <ardb@kernel.org> wrote:
>> > On Mon, 19 Feb 2024 at 11:56, Ard Biesheuvel <ardb@kernel.org> wrote:

>> > https://godbolt.org/z/GTnf3vPaT
>>
>> I could reproduce the issue on v6.8-rc5 using arm64 defconfig
>> and x86_64-gcc-5.5.0-nolibc-aarch64-linux.tar.xz from
>> https://cdn.kernel.org/pub/tools/crosstool/files/bin/x86_64/5.5.0/:
>>
>
> OK, I managed to do so as well.
>
> And GCC 6.4 from the same source works correctly.
>
> Not sure whether there are any plans to bump the minimal GCC version
> any time soon (cc'ing Arnd), but we should probably drop this change
> until that happens.

From what I can tell, we may as well formally raise the minimum
gcc version to 8.1+ already, as that is a version that is
actually used in distros, and we have been on 5.1+ for a few
years already.

Not sure if there are any other benefits to gcc-8 besides
allowing minor cleanups.

gcc-9 would bring --std=gnu2x support, but it may be too
early for that.

      Arnd