On Wed, 2016-08-10 at 20:11 +0530, Bharata B Rao wrote: > Hi, > > With CPU core hotplug support in pseries-2.7, we will have to specify > the compat type using -global only as we don't yet take care of parsing > -cpu cputype,compat=. > > There have been patches to support that: > > sPAPR specific one: > https://lists.nongnu.org/archive/html/qemu-devel/2016-06/msg07564.html > > PPC generic one: > https://lists.gnu.org/archive/html/qemu-devel/2016-07/msg02676.html > > but the patch isn't upstream yet. > > The result is that instead of specifying > > -cpu host,compat=power7 for pseries-2.7, we will have to use > > -cpu host -global driver=host-powerpc64-cpu,property=compat,value=power7 > > This behaviour is specific to pseries-2.7 and for earlier machine types > the original way of specifying compat with -cpu works. > > Will this be a concern for libvirt ? Would it be difficult for libvirt to > switch to -global when generating QEMU cmdline for compat mode for pseries-2.7 > machine. > > Or, should we just include one of the above patches so that > -cpu cputype,compat= continues to work for peseries-2.7 ?
I filed bugs for this yesterday: https://bugzilla.redhat.com/1365643 (QEMU) https://bugzilla.redhat.com/1365647 (libvirt) libvirt could certainly be adapted to use -global, but that would not benefit people running QEMU directly, or driving QEMU 2.7 with any existing libvirt version. Plus, it would not solve the issue with CPU models that include a dot in their names, as you already noted. I won't comment on the patches because I'm not qualified to :) But, assuming they both restore the previous behaviour, getting either one into 2.7 would definitely be great. -- Andrea Bolognani / Red Hat / Virtualization
