Re: [PATCH v11 RESEND 9/9] arm64: armv8_deprecated: apply FEAT_LSUI for swpX emulation.

Marc Zyngier
2025-12-15T09:33:50Z

On Sun, 14 Dec 2025 11:22:48 +0000,
Yeoreum Yun <yeoreum.yun@arm.com> wrote:
>
> Apply the FEAT_LSUI instruction to emulate the deprecated swpX
> instruction, so that toggling of the PSTATE.PAN bit can be removed when
> LSUI-related instructions are used.
>
> Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>

It really begs the question: what are the odds of ever seeing a CPU
that implements both LSUI and AArch32?

This seems extremely unlikely to me.

M.

--
Without deviation from the norm, progress is not possible.