On 7/17/2026 10:30 PM, Cédric Le Goater wrote: > On 7/18/26 06:52, Pierrick Bouvier wrote: >> On 7/17/2026 9:14 PM, Michael Tokarev wrote: >>> On 7/17/26 22:40, Pierrick Bouvier wrote: >>> >>>> https://gitlab.com/qemu-project/qemu/-/blob/master/hw/vfio/Kconfig? >>>> ref_type=heads#L5 >>>> >>>> ``` >>>> config VFIO >>>> bool >>>> depends on LINUX >>>> ``` >>>> >>>> Incorrect, and it should exclude Linux hosts not supporting VFIO. >>>> At least sparc64 to fix the current issue. >>> >>> Shouldn't there be "depends on LINUX & KVM" ? At least, this >>> way we can do --disable-kvm and it will work. >>> >> >> I think it's a safe choice, but not sure if we are supposed to be able >> to use the exotic combination of vfio with tcg also. Maybe it doesn't >> make any sense technically though, I don't know the arcane of vfio. > > VFIO works in some heterogeneous configurations, aarch64 TCG running > on an x86 host for instance. The opposite doesn't. ppc64 TCG on an x86 > used to work. The limitations primarily stem from architectural > differences in the host/guest memory mode, CPU/IOMMU address spaces, > assumptions, etc. >
Thanks, I remembered trying the first heterogeneous configuration you mentioned, but it was some time ago, so I was not completely sure. >> @Cédric, Any idea of which matrix of host/target is supposed to be >> supported? > > Overall, heterogeneous TCG configurations happen to work by accident. > I would not consider them supported. > Should we forbid them explicitly? In this case, we can restrict config VFIO to LINUX & KVM. > With KVM, the supported architectures are x86, aarch64, s390x, ppc64. > C. > Regards, Pierrick
