Hi,
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.
Well, I'm not sure how many CPU will have both ID_AA64PFR0_EL1.EL0 bit as 0b0010 and FEAT_LSUI (except FVP currently) -- at least the CPU what I saw, most of them set ID_AA64PFR0_EL1.EL0 as 0b0010.
If you this seems useless, I don't have any strong comments whether drop patches related to deprecated swp instruction parts (patch 8-9 only) or not. (But, I hope to pass this decision to maintaining perspective...)
M.
-- Without deviation from the norm, progress is not possible.
-- Sincerely, Yeoreum Yun