On 15/07/2015 16:14, Michael S. Tsirkin wrote: > On Wed, Jul 15, 2015 at 02:47:24PM +0200, Paolo Bonzini wrote: >> >> >> On 15/07/2015 14:21, Michael S. Tsirkin wrote: >>>>> Disable scsi passthrough by default since it was incompatible with >>>>> virtio 1.0. For legacy machine types, keep this on by default. >>>>> >>>>> Cc: Stefan Hajnoczi <stefa...@redhat.com> >>>>> Cc: Kevin Wolf <kw...@redhat.com> >>>>> Cc: qemu-bl...@nongnu.org >>>>> Signed-off-by: Jason Wang <jasow...@redhat.com> >>> Seems risky for 2.4. modern is off by default for now. Can't we limit >>> the change to when modern is enabled? >> >> That would have the effect of disabling a feature when you turn on modern. > > What's wrong with that?
Weren't you complaining about it a few hours ago? :) >>> I suggested changing this from bool to on/off/auto, and >>> make auto mean !modern. >> >> No, please do it like Jason did. The SCSI feature effectively had to be >> enabled explicitly already, the requests were marked as unsupported. > > I didn't know. How is it enabled? It's enabled by default in QEMU, but disabled by default in libvirt. And it only works if you pass a whole _disk_ (not a partition or logical volume) to QEMU, which is definitely not the common case. It can just be documented in the release notes; the feature is still available, and libvirt won't be broken because it adds explicitly both scsi=on and scsi=off. Paolo
