From: Marc Zyngier <maz@kernel.org>
To: Jia He <justin.he@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org,
Lorenzo Pieralisi <lpieralisi@kernel.org>,
Mark Brown <broonie@kernel.org>,
Sascha Bischoff <Sascha.Bischoff@arm.com>,
Fuad Tabba <tabba@google.com>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Oliver Upton <oupton@kernel.org>,
linux-kernel@vger.kernel.org, Bin Guo <guobin@linux.alibaba.com>
Subject: Re: [PATCH] arm64/sysreg: Fix BWE field encoding in ID_AA64DFR2_EL1
Date: Wed, 01 Jul 2026 15:29:18 +0100 [thread overview]
Message-ID: <86v7aypyv5.wl-maz@kernel.org> (raw)
In-Reply-To: <20260630222347.1449737-1-justin.he@arm.com>
On Tue, 30 Jun 2026 23:23:47 +0100,
Jia He <justin.he@arm.com> wrote:
>
> Commit 93d7356e4b30 ("arm64: sysreg: Describe ID_AA64DFR2_EL1 fields")
> encodes the FEAT_BWE2 value of the BWE field as '0b0002'. Binary
> literals only accept the digits 0 and 1, so the intended value is 2,
> i.e. 0b0010.
>
> The macro generated by gen-sysreg.awk currently expands to
> #define ID_AA64DFR2_EL1_BWE_FEAT_BWE2 UL(0b0002)
> is not legal C and would fail to compile if any in-tree code referenced
> it. At present no caller uses this enum value, so the kernel still
> builds cleanly, but the bug is latent.
>
> Fix the typo by using the correct binary literal 0b0010.
>
> Cc: Bin Guo <guobin@linux.alibaba.com>
> Fixes: 93d7356e4b30 ("arm64: sysreg: Describe ID_AA64DFR2_EL1 fields")
> Signed-off-by: Jia He <justin.he@arm.com>
> Reviewed-by: Mark Brown <broonie@kernel.org>
> ---
> arch/arm64/tools/sysreg | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm64/tools/sysreg b/arch/arm64/tools/sysreg
> index bc1788b1662b..7cb61aca3797 100644
> --- a/arch/arm64/tools/sysreg
> +++ b/arch/arm64/tools/sysreg
> @@ -1806,7 +1806,7 @@ Res0 15:8
> UnsignedEnum 7:4 BWE
> 0b0000 NI
> 0b0001 FEAT_BWE
> - 0b0002 FEAT_BWE2
> + 0b0010 FEAT_BWE2
Well, that was embarrassing. FWIW (and given the original patch,
that's not much):
Acked-by: Marc Zyngier <maz@kernel.org>
M.
--
Without deviation from the norm, progress is not possible.
next prev parent reply other threads:[~2026-07-01 14:29 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-30 22:23 [PATCH] arm64/sysreg: Fix BWE field encoding in ID_AA64DFR2_EL1 Jia He
2026-07-01 14:29 ` Marc Zyngier [this message]
2026-07-01 17:09 ` Oliver Upton
2026-07-02 12:58 ` Will Deacon
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