On Tue, Dec 18, 2018 at 01:30:23PM +0100, Paolo Bonzini wrote: > On 18/12/18 04:07, Peter Xu wrote: > > On Mon, Dec 17, 2018 at 03:31:14PM +0800, Peter Xu wrote: > >> IR has been there for a long time and long time no bug reported. > >> Let's turn it on by default to match general hardwares. Providing > >> compatibility bit for QEMU<=3.1. > >> > >> Signed-off-by: Peter Xu <pet...@redhat.com> > > I forgot that IR will depend on split kernel irqchip and by default > > that's still "on" so "-M q35 -device intel-iommu" may not be able to > > boot correctly with all the default values and instead QEMU will ask > > user to turn on split irqchip. > > > > Paolo/Michael, do you think it would make any sense to turn the > > default kernel-irqchip machine parameter to split starting from qemu > > 4.0? Since AFAIU it should have little degradation to performance but > > at the same time it reduces kvm attack serface, which seems good. > > The main problem with that would be the minimal required kernel version, > which is 4.4 for split irqchip. But, we're already planning to make it > 4.5 so it's not an issue. Go for it. :)
Thanks Paolo. :) I'll try to prepare a patch for it. Regards, -- Peter Xu
