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Tsirkin" , Jason Wang , qemu-devel@nongnu.org, "Dr . David Alan Gilbert" , Eric Auger , Alex Williamson , Paolo Bonzini , Igor Mammedov Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Peter Xu writes: > Hi, Dan, > > On Thu, Sep 02, 2021 at 02:53:00PM +0100, Daniel P. Berrang=C3=A9 wrote: >> The correct ordering of devices/backends is generally pretty obvious >> for libvirt to determine. Most of the problems we've had related to >> ordering are on the QEMU side, because the ARGV given to QEMU made >> correct sense if parsed left-to-right, but QEMU didn't actually process >> them in that order. We've patched QEMU to hack around its inability to >> honour the CLI order repeatedly. > > Is there a pointer to the problem? Just an example: 9ea18ed25a "vl: Fix -drive / -blockdev persistent reservation management cda4aa9a5a "vl: Create block backends before setting machine properties" >> Being completely self-ordering on the QEMU side using a topological >> sort would be neat from a conceptual purity POV, but that is quite a >> challenge to implement and I'm not convinced it is worth it, compared >> to other problems we want to spend time on. > > I just noticed there can also be dependency between the buses; that canno= t be > fixed by ordering of classes indeed as either proposed in this series, or > introduce a new priority. --verbose?