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From: Nam Cao <namcao@linutronix.de>
To: "Thomas Weißschuh" <thomas.weissschuh@linutronix.de>
Cc: "Paul Walmsley" <pjw@kernel.org>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Albert Ou" <aou@eecs.berkeley.edu>,
	"Alexandre Ghiti" <alex@ghiti.fr>,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	"André Almeida" <andrealmeid@igalia.com>,
	"Mathieu Desnoyers" <mathieu.desnoyers@efficios.com>,
	"Thomas Gleixner" <tglx@kernel.org>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Sebastian Andrzej Siewior" <bigeasy@linutronix.de>
Subject: Re: [PATCH v3 5/5] riscv: vdso: Implement __vdso_futex_robust_try_unlock()
Date: Mon, 20 Jul 2026 13:50:47 +0200	[thread overview]
Message-ID: <87fr1dev6w.fsf@yellow.woof> (raw)
In-Reply-To: <20260720134032-032dc788-414c-4d7e-b72b-57fa5311adc8@linutronix.de>

Thomas Weißschuh <thomas.weissschuh@linutronix.de> writes:
> I don't think we would get such an error currently.
> The cc-option check in the Makefile will fall back to non-zacas for the
> compat vDSO, but arch_futex_robust_unlock_get_pop() will treat it as zacas.

Switching to .option and the cc-option will be gone. See below.

> Ok. I don't understand the .option suggestion :-)

We wouldn't touch -march compile option in Makefiles. Instead, we do

.option push
.option arch, <extension name>
<instruction requiring extension>
.option pop

Whenever the ZACAS instruction is used.

See
https://lore.kernel.org/lkml/20260717-riscv-no-zacas-zabha-in-march-v1-1-82b5b0799fb6@iscas.ac.cn/

Nam

WARNING: multiple messages have this Message-ID (diff)
From: Nam Cao <namcao@linutronix.de>
To: "Thomas Weißschuh" <thomas.weissschuh@linutronix.de>
Cc: "Paul Walmsley" <pjw@kernel.org>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Albert Ou" <aou@eecs.berkeley.edu>,
	"Alexandre Ghiti" <alex@ghiti.fr>,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	"André Almeida" <andrealmeid@igalia.com>,
	"Mathieu Desnoyers" <mathieu.desnoyers@efficios.com>,
	"Thomas Gleixner" <tglx@kernel.org>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Sebastian Andrzej Siewior" <bigeasy@linutronix.de>
Subject: Re: [PATCH v3 5/5] riscv: vdso: Implement __vdso_futex_robust_try_unlock()
Date: Mon, 20 Jul 2026 13:50:47 +0200	[thread overview]
Message-ID: <87fr1dev6w.fsf@yellow.woof> (raw)
In-Reply-To: <20260720134032-032dc788-414c-4d7e-b72b-57fa5311adc8@linutronix.de>

Thomas Weißschuh <thomas.weissschuh@linutronix.de> writes:
> I don't think we would get such an error currently.
> The cc-option check in the Makefile will fall back to non-zacas for the
> compat vDSO, but arch_futex_robust_unlock_get_pop() will treat it as zacas.

Switching to .option and the cc-option will be gone. See below.

> Ok. I don't understand the .option suggestion :-)

We wouldn't touch -march compile option in Makefiles. Instead, we do

.option push
.option arch, <extension name>
<instruction requiring extension>
.option pop

Whenever the ZACAS instruction is used.

See
https://lore.kernel.org/lkml/20260717-riscv-no-zacas-zabha-in-march-v1-1-82b5b0799fb6@iscas.ac.cn/

Nam

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  reply	other threads:[~2026-07-20 11:50 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-17  8:06 [PATCH v3 0/5] riscv: vdso: Implement __vdso_futex_robust_try_unlock() Nam Cao
2026-07-17  8:06 ` Nam Cao
2026-07-17  8:06 ` [PATCH v3 1/5] riscv: compat_vdso: switch to standard kbuild rule Nam Cao
2026-07-17  8:06   ` Nam Cao
2026-07-17 12:17   ` Thomas Weißschuh
2026-07-17 12:17     ` Thomas Weißschuh
2026-07-17  8:06 ` [PATCH v3 2/5] riscv: compat_vdso: Allow *.c source files Nam Cao
2026-07-17  8:06   ` Nam Cao
2026-07-17 12:19   ` Thomas Weißschuh
2026-07-17 12:19     ` Thomas Weißschuh
2026-07-17  8:06 ` [PATCH v3 3/5] riscv: compat_vdso: Introduce COMPAT_MARCH variable Nam Cao
2026-07-17  8:06   ` Nam Cao
2026-07-17 12:19   ` Thomas Weißschuh
2026-07-17 12:19     ` Thomas Weißschuh
2026-07-17  8:06 ` [PATCH v3 4/5] riscv: compat_vdso: Build with zacas if available Nam Cao
2026-07-17  8:06   ` Nam Cao
2026-07-17 12:23   ` Thomas Weißschuh
2026-07-17 12:23     ` Thomas Weißschuh
2026-07-17 12:38   ` Vivian Wang
2026-07-17 12:38     ` Vivian Wang
2026-07-17 12:44     ` Vivian Wang
2026-07-17 12:44       ` Vivian Wang
2026-07-20 11:17     ` Nam Cao
2026-07-20 11:17       ` Nam Cao
2026-07-17  8:06 ` [PATCH v3 5/5] riscv: vdso: Implement __vdso_futex_robust_try_unlock() Nam Cao
2026-07-17  8:06   ` Nam Cao
2026-07-17 12:37   ` Thomas Weißschuh
2026-07-17 12:37     ` Thomas Weißschuh
2026-07-20 11:37     ` Nam Cao
2026-07-20 11:37       ` Nam Cao
2026-07-20 11:42       ` Thomas Weißschuh
2026-07-20 11:42         ` Thomas Weißschuh
2026-07-20 11:50         ` Nam Cao [this message]
2026-07-20 11:50           ` Nam Cao

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