On Wed, Mar 22, 2023 at 06:36:14AM -0600, Alex Williamson wrote: > On Wed, 22 Mar 2023 09:27:16 -0300 > Jason Gunthorpe <jgg@xxxxxxxxxx> wrote: > > > On Tue, Mar 21, 2023 at 04:47:37PM -0600, Alex Williamson wrote: > > > On Tue, 21 Mar 2023 19:20:37 -0300 > > > Jason Gunthorpe <jgg@xxxxxxxxxx> wrote: > > > > > > > On Tue, Mar 21, 2023 at 03:01:12PM -0600, Alex Williamson wrote: > > > > > > > > > > Though it would be nice if qemu didn't need two implementations so Yi > > > > > > I'd rather see a new info in this series as well and qemu can just > > > > > > consistently use dev_id and never bdf in iommufd mode. > > > > > > > > > > We also need to consider how libvirt determines if QEMU has the kernel > > > > > support it needs to pass file descriptors. It'd be a lot cleaner if > > > > > this aligned with the introduction of vfio cdevs. > > > > > > > > Yes, that would be much better if it was one package. > > > > > > > > But this is starting to grow and we have so many threads that need to > > > > progress blocked on this cdev enablement :( > > > > > > > > Could we go forward with the cdev main patches and kconfig it to > > > > experimental or something while the rest of the parts are completed > > > > and tested through qemu? ie move the vfio-pci reset enablment to after > > > > the cdev patches? > > > > > > We need to be able to guarantee that there cannot be any significant > > > builds of the kernel with vfio cdev support if our intention is to stage > > > it for libvirt. We don't have a global EXPERIMENTAL config option any > > > more. Adding new code under BROKEN seems wrong. Fedora ships with > > > STAGING enabled. A sternly worded Kconfig entry is toothless. What is > > > the proposed mechanism to make this not look like a big uncompiled code > > > dump? Thanks, > > > > I would suggest a sternly worded kconfig and STAGING. > > > > This isn't such a big issue, we are trying to say that a future > > released qemu is not required to work on older kernels with a STAGING > > kconfig mark. > > > > IOW we are saying that qemu release X.0 with production iommufd > > requires kernel version > x.y and just lightly reflecting this into > > the kconfig. > > > > qemu should simply not support iommufd if it finds itself on a old > > kernel. > > Inferring features based on kernel versions doesn't work in a world > where downstreams backport features to older kernels. I don't mean actual kernel versions as a compatability test. I mean it as documention and an expected "support" window. ie we are disclaiming support for STAGING kernel as a matter of documentation, not code. Jason
