> On 27 May 2026, at 9:34 PM, Eric Auger <[email protected]> wrote: > > On 5/27/26 5:56 PM, Khushit Shah wrote: >> So you are saying, if I do, >> -cpu host,sve=on,SYSREG_ID_AA64PFR0_SVE=0 >> QEMU will still show sve capabilities to the guest? > Yes that's what I expect. Require more extensive testing though. That > could be way to handle coexistence of different levels of granulaity. > Lowest level applies first, overriden by legacy compositive options. I > guess if you plan to introduce other layers of compositive props you > will most probably handle this situation too. >
I am sure this at-least does not work with sve, because arm_cpu_sve_finalize() just takes looks at the PFR0.SVE field and If value is 0 sve is 'off' otherwise 'on’. What you describe might work for legacy props backed by prop_* boolean variables in ARMCPU like pauth (backed by cpu->prop_pauth). I have not tested this. I maybe wrong if some prop ordering magic happens at machine level. My plan is to just parse properties in order they arrive in cmdline :) Warm Regards, Khushit
