Re: [PATCH v2 1/1] arm64/cpufeature: Add arm64.nomte to override id-reg
From: Marc Zyngier <maz@kernel.org>
Date: 2021-07-29 08:49:35
Also in:
linux-mediatek
On Thu, 29 Jul 2021 03:07:12 +0100, [off-list ref] wrote:
From: Yee Lee <redacted> Add an alias, "arm64.nomte", to override id-reg and
This isn't just an alias. This patch does two things: - it allows the ID_AA64PFR1_EL1.MTE shadow capability to be set from the command line, - it provides the arm64.nomte alias that sets the above to 0 to disable the MTE feature.
suppress mte feature.
s/mte/MTE/ Maybe also worth indicating *why* this is needed. Possible justifications include errata workarounds, performance issues... Pick your own.
quoted hunk ↗ jump to hunk
Suggested-by: Marc Zyngier <maz@kernel.org> Suggested-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Yee Lee <redacted> --- arch/arm64/kernel/idreg-override.c | 2 ++ 1 file changed, 2 insertions(+)diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c index 53a381a7f65d..d8e606fe3c21 100644 --- a/arch/arm64/kernel/idreg-override.c +++ b/arch/arm64/kernel/idreg-override.c@@ -54,6 +54,7 @@ static const struct ftr_set_desc pfr1 __initconst = { .override = &id_aa64pfr1_override, .fields = { { "bt", ID_AA64PFR1_BT_SHIFT }, + { "mte", ID_AA64PFR1_MTE_SHIFT}, {} }, };@@ -100,6 +101,7 @@ static const struct { { "arm64.nopauth", "id_aa64isar1.gpi=0 id_aa64isar1.gpa=0 " "id_aa64isar1.api=0 id_aa64isar1.apa=0" }, + { "arm64.nomte", "id_aa64pfr1.mte=0" }, { "nokaslr", "kaslr.disabled=1" }, };
This needs to be documented in kernel-parameters.txt. See the nobti and nopauth options for guidance. Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel