On Fri, 13 May 2022 11:31:42 +0200 Thomas Lamprecht <t.lampre...@proxmox.com> wrote:
> Am 5/13/22 um 10:57 schrieb Stoiko Ivanov: > ..snip.. > > alternatively we could document this in the 7.2 release notes and ask > > users of problematic hardware to set this explicitly > > This all resembles quite a bit the switch from nested KVM to be enabled, > which we caught upfront and actively disabled to avoid trouble on migration > due to QEMU not being yet ready for that change, and only enabled it in the > next major release (6.0 IIRC) where we could be sure that a new enough QEMU > is available. > > The difference here is that: > * we may never be sure that all setups out there support IOMMU, at least not > if we don't get another major divider like the switch from 32bit to 64bit > was agreed - I think we want to switch to default enabled eventually - my idea was to have it even more visible during a major version-upgrade ... OTOH since we just released 7.2 and have a known-issues section - I think adding it there and linking to that should work fine. > > * we already switched it on now, sow disabling it may also break some setups > that never did so manually. my gut-feeling would be that most people who need it enabled (for pci-passtrough) would follow the docs (of the past years) and set it explicitly [0] - but you're right - it's a regression we would need to document too. > FWIW, we could also disable this dynamically with a modprobe cfg file that > disables it if: > - not manually enabled already (grep for that) > - an older CPU (family) is present, where the cutoff would need to be > decided maybe I'm missing something - but intel_iommu is builtin (not a module) - and options for those need to be provided on the kernel commandline [1]? and while (semi-optionally) shipping a modprobe.conf snippet could work, I wouldn't want to `sed` in our user's `/etc/default/grub`, `/etc/kernel/cmdline` in a postinst. we could add it to the NEWS file for the packages - to give it some visibility though)? [0] we should update our docs on pci-passthrough (mostly meant as note to myself) [1] https://www.kernel.org/doc/html/v4.14/admin-guide/kernel-parameters.html _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel
