Hi Peter, On 2/26/20 12:58 PM, Auger Eric wrote: > 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?
I sent an RFC prototyping what we had in mind - I think - together with Drew. [RFC 0/2] hw/arm/virt: kvm: allow gicv3 by default if host does not support v2 This was discussed earlier in that thread: https://www.mail-archive.com/qemu-devel@nongnu.org/msg674469.html. It should not break any compatibility as the only case we are supposed to change here was aborting before. Thanks Eric > > Thanks > > Eric > >> >> Thanks, >> drew >> >>
