On Wed, Aug 10, 2016 at 11:52:12AM -0300, Eduardo Habkost wrote: > On Wed, Aug 10, 2016 at 08:11:16PM +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 believe we should include the generic PPC patch ("ppc: parse > cpu features once") in 2.7.
Actually, see my reply to the generic patch: I believe we don't need to change all machines in 2.7, but just spapr (that is probably the only buggy case). The other machines still use cpu_ppc_init()/cpu_generic_init() and should work normally. -- Eduardo
