From: Marc Zyngier <maz@kernel.org>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
kvmarm <kvmarm@lists.cs.columbia.edu>,
David Brazdil <dbrazdil@google.com>,
Android Kernel Team <kernel-team@android.com>,
Ard Biesheuvel <ardb@kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] arm64: Work around broken GCC handling of "S" constraint
Date: Mon, 07 Dec 2020 19:04:44 +0000 [thread overview]
Message-ID: <87360h5tf7.wl-maz@kernel.org> (raw)
In-Reply-To: <ce1666ea-eb6f-33d6-cfd8-934bfcf7e336@arm.com>
Hi Robin,
On Mon, 07 Dec 2020 18:42:23 +0000,
Robin Murphy <robin.murphy@arm.com> wrote:
>
> On 2020-12-07 17:47, Ard Biesheuvel wrote:
> > On Mon, 7 Dec 2020 at 18:41, Marc Zyngier <maz@kernel.org> wrote:
> >>
> >> On 2020-12-07 17:19, Ard Biesheuvel wrote:
> >>> (resend with David's email address fixed)
> >>
> >> Irk. Thanks for that.
> >>
> >>>>> +#ifdef CONFIG_CC_HAS_BROKEN_S_CONSTRAINT
> >>>>> +#define SYM_CONSTRAINT "i"
> >>>>> +#else
> >>>>> +#define SYM_CONSTRAINT "S"
> >>>>> +#endif
> >>>>> +
> >>>>
> >>>> Could we just check GCC_VERSION here?
> >>
> >> I guess we could. But I haven't investigated which exact range of
> >> compiler is broken (GCC 6.3 seems fixed, but that's the oldest
> >> I have apart from the offending 4.9).
> >>
> >
> > I tried 5.4 on godbolt, and it seems happy. And the failure will be
> > obvious, so we can afford to get it slightly wrong and refine it
> > later.
>
> FWIW the Linaro 14.11, 15.02 and 15.05 releases of GCC 4.9.3 seem to
> build rc7 without complaint. The only thing older that I have to hand
> is Ubuntu's GCC 4.8.4, which Kbuild chokes on entirely now.
Can you try kvmarm/next? David's PSCI relay is breaking badly here.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
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next prev parent reply other threads:[~2020-12-07 19:06 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-07 15:43 [PATCH] arm64: Work around broken GCC handling of "S" constraint Marc Zyngier
2020-12-07 17:17 ` Ard Biesheuvel
2020-12-07 17:19 ` Ard Biesheuvel
2020-12-07 17:41 ` Marc Zyngier
2020-12-07 17:47 ` Ard Biesheuvel
2020-12-07 18:42 ` Robin Murphy
2020-12-07 19:04 ` Marc Zyngier [this message]
2020-12-07 19:22 ` Robin Murphy
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