Hi Peter, On 2/26/20 10:17 AM, Andrew Jones wrote: > On Wed, Feb 26, 2020 at 08:56:03AM +0000, Peter Maydell wrote: >> On Wed, 26 Feb 2020 at 08:52, Andrew Jones <drjo...@redhat.com> wrote: >>> Although, many QEMU command line users still won't know what to do >>> without an explicit "Try -machine gic-version=host" hint, so that >>> might be nice to add too. >> >> In the GIC code we don't know if the machine even has a >> gic-version property, so we're not in the right place to try to >> produce that message. >> > > Ah yes, we use qdev_init_nofail() in virt::create_gic(), so there's > no chance to append another hint at the machine level. > > And what about when machine.gic-version is not provided and KVM is > in use? Shouldn't we try version '2', as we do now, but then also > '3', if '2' fails, before erroring out?
In case of KVM accelerated mode we could effectively probe v2 first and if not supported choose v3, as mentioned by Drew. Couldn't kvm_arm_vgic_probe() return a bitmap by calling kvm_create_device on both versions in dryrun mode? Thanks Eric > > Thanks, > drew > >
