From: David Laight <david.laight.linux@gmail.com>
To: Nicolas Pitre <nico@fluxnic.net>
Cc: "Borislav Betkov" <bp@alien8.de>,
"Ingo Molnar" <mingo@redhat.com>,
"Thomas Gleinxer" <tglx@linutronix.de>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
x86@kernel.org, "Andrew Morton" <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
"Peter Zijlstra" <peterz@infradead.org>,
"Uwe Kleine-König" <u.kleine-koenig@baylibre.com>,
rodrigo.alencar@analog.com, jic23@kernel.org
Subject: Re: [PATCH 0/2] x86: Use "er" asm constriant for add/sub
Date: Mon, 3 Aug 2026 16:39:55 +0100 [thread overview]
Message-ID: <20260803163955.627bdd3f@pumpkin> (raw)
In-Reply-To: <11o7545n-7569-3p9r-1q77-8nor8513r6n1@syhkavp.arg>
On Mon, 3 Aug 2026 10:49:40 -0400 (EDT)
Nicolas Pitre <nico@fluxnic.net> wrote:
> On Mon, 3 Aug 2026, David Laight wrote:
>
> > The x86 instruction set only supports 32bit signed immediate values
> > for add/sub.
> > Replace the "ir" constraint with "er" to avoid build errors.
> >
> > Found by a patch that added used mul_u64_add_u64_div_u64() to
> > do a rounding divide by 2^32 (perhaps not the best way to do this).
> >
> > A quick grep only found one other affected file.
>
> Would be a good idea adding those cases to the test module.
They fail to compile so it isn't a big deal.
David
>
>
> Nicolas
prev parent reply other threads:[~2026-08-03 15:40 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-03 9:47 [PATCH 0/2] x86: Use "er" asm constriant for add/sub David Laight
2026-08-03 9:47 ` [PATCH 1/2] lib: mul_u64_add_u64_div_u64: Fix addition of large constants David Laight
2026-08-03 10:08 ` H. Peter Anvin
2026-08-03 9:47 ` [PATCH 2/2] x86/local: local_add/local_sub: Support large immediate values David Laight
2026-08-03 10:01 ` Peter Zijlstra
2026-08-03 10:07 ` H. Peter Anvin
2026-08-03 9:59 ` [PATCH 0/2] x86: Use "er" asm constriant for add/sub Peter Zijlstra
2026-08-03 14:49 ` Nicolas Pitre
2026-08-03 15:39 ` David Laight [this message]
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