Re: [libvirt] [Qemu-devel] [PATCH v3 2/2] Add configure option --enable-pc-1-0-qemu-kvm

Am 22.09.2014 um 15:05 schrieb Alex Bligh: >>> Sadly that is not true. For instance on Ubuntu Precise >>> it's invoked as qemu-system-x86_64 by at least one >>> management application known to me. >> >> Well change it to call qemu-kvm then :) >> Also what happens if you install qemu as well? >> Does it conflict? > > I'm not an Ubuntu maintainer but AFAIK qemu-kvm is deprecated. > It may only be there to support upgrades. > > We still need to support migration from qemu running on Precise > to qemu running on Trusty. The trusty instance may not have > qemu-kvm installed. If we were looking at argv[0], we'd > really want to look at it on the /sending/ machine. > > Forcing qemu to be involved as qemu-kvm solely on the basis > some users might want to migrate a VM in from a previous > version does not sound practical. > >>> I'm not quite sure why you say "legacy management >>> applications". >> >> Because any non legacy one can be patched. > > Well this is where we diverge. I think the distro needs > a way to change the default behaviour, i.e. so the existing > command line will do something different. > >>> This applies to /any/ management application. >>> Unless we're going to burden every management application >>> with this problem, we need to fix it. >>> >>> Just as a reminder, the ./configure value defaults to >>> off, which means there is no change in current behaviour. >> >> Yes but this still perpetuates the mess. >> >> If you prefer using -M pc-1.0, add a new property >> and teach management to set it. >> >> But no silent compile-time behind the scenes changes please. > > OK, how about we keep the aliases, and make pc-1.0 > default to the pc-1.0-qemu-git. We then add a command > line option to make pc-1.0 mean pc-1.0-qemu-kvm, with > that obviously defaulting to off. > > Then distros can then put the option in > /etc/qemu/target-x86_64.conf or whatever. What about adding a bool property "qemu-kvm-compat" to the MachineClass? Then a qemu-kvm shell script (like SUSE uses) can pass -global machine.qemu-kvm-compat=on whereas qemu-system-x86_64 would run in the default non-qemu-kvm mode (config on disk would affect both). It would also allow running -machine pc-0.15,qemu-kvm-compat=on, ditching lots of new machine names and avoiding the name bikeshedding. Regards, Andreas

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