On Thu Oct 2, 2025 at 8:27 PM CEST, Demi Marie Obenour wrote: > On 10/2/25 06:10, Andrew Cooper wrote: >> On 01/10/2025 9:01 pm, Milan Djokic wrote: >>> Signed-off-by: Milan Djokic <milan_djo...@epam.com> >>> >>> --- >>> XEN_DOMCTL_get_address_size hypercall is not implemented for arm (only for >>> x86) >>> It would be useful to have this hypercall supported for arm64, in order to >>> get >>> current guest addressing mode and also to verify that >>> XEN_DOMCTL_set_address_size >>> performs switch to target addressing mode (instead of relying on its >>> returned error code only). >> >> Please don't copy this misfeature of x86 PV guests into ARM. >> >> Letting domains be of variable bitness after domain create leads to a >> whole lot of bugs, many security relevant. >> >> 32bit vs 64bit should be an input to domain_create(), not something that >> is edited after the domain has been constructed. > > Does this mean that Xen guests cannot support multiarch?
HVM/PVH x86_64 cannot not be multiarch. All APs start in 16bit and proceed to 32 and 64 bit mode, in that order. It's only PV that has fixed bitness. Cheers, Alejandro
