On Thu, Jun 01, 2017 at 03:09:15PM +0200, Greg Kurz wrote: > On Thu, 1 Jun 2017 13:59:14 +0200 > Cédric Le Goater <c...@kaod.org> wrote: > > > On 06/01/2017 08:52 AM, David Gibson wrote: > > > On Wed, May 31, 2017 at 10:58:57AM +0200, Greg Kurz wrote: > > >> On Wed, 31 May 2017 12:57:48 +1000 > > >> David Gibson <da...@gibson.dropbear.id.au> wrote: > > >>> [...] > > >>>> All old non-pseries machine types already complain when started with > > >>>> a POWER7 or newer CPU. Providing the extra error message looks weird: > > >>>> > > >>>> qemu-system-ppc64 -machine ppce500 \ > > >>>> -cpu POWER7,compat=power6 > > >>>> qemu-system-ppc64: CPU 'compat' property is deprecated and has no > > >>>> effect; > > >>>> use max-cpu-compat machine property instead > > >>>> MMU model 983043 not supported by this machine. > > >>>> > > >>>> but I guess it's better than crashing. :) > > >>> > > >>> Well, sure POWER7 doesn't make sense for an e500 machine for other > > >>> reasons. But POWER7 or POWER8 _would_ make sense for powernv, where > > >>> compat= doesn't. > > >>> > > >> > > >> The powernv machine type doesn't even support CPU features at all: > > >> > > >> chip_typename = g_strdup_printf(TYPE_PNV_CHIP "-%s", > > >> machine->cpu_model); > > >> if (!object_class_by_name(chip_typename)) { > > >> error_report("invalid CPU model '%s' for %s machine", > > >> machine->cpu_model, > > >> MACHINE_GET_CLASS(machine)->name); > > >> exit(1); > > >> } > > > > > > Ah, well, that's another bug, but not one that's in scope for this > > > series. > > > > PowerNV is still work in progress. I would not worry about it too much. > > > > Of course and this isn't the purpose of the discussion actually. We were > talking about CPU features being relevant or not depending on the machine > type. > > But I'm not even sure that CPU features are useful at all for ppc, not to > say very confusing (otherwise this series wouldn't be needed for example). > > Speaking of PowerNV, just as an example, I guess the fix would be to > forbid machine->cpu_model if it contains features. And probably the same > for all other machine types, except pseries for backward compatibility > reasons.
I don't think that's correct in principle. I can imagine CPU properties it might make sense to really set on the cpu, regardless of machine type. A quick look says we don't have any such at the moment, but I don't think it's something we should prevent as a matter of policy. -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
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