On Thu, Aug 20, 2020 at 02:15:04PM +1000, David Gibson wrote: > On Wed, Aug 19, 2020 at 10:11:28PM -0400, Eduardo Habkost wrote: > > On Thu, Aug 20, 2020 at 11:17:26AM +1000, David Gibson wrote: > > > On Fri, Aug 14, 2020 at 05:54:16PM -0300, Daniel Henrique Barboza wrote: > > > > The pSeries machine does not support asymmetrical NUMA > > > > configurations. > > > > > > This seems a bit oddly specific to have as a global machine class > > > property. > > > > > > Would it make more sense for machines with specific NUMA constraints > > > to just verify those during their initialization? > > > > This would be much simpler. However, I like the idea of > > representing machine-specific configuration validation rules as > > data that can eventually be exported to management software. > > Ah, ok, so basically the usual tradeoff between flexibility and > advertisability. > > So, in that case, I guess the question is whether we envisage "no > assymmetry" as a constraint common enough that it's worth creating an > advertisable rule or not. If we only ever have one user, then we > haven't really done any better than hard coding the constraint in the > manageent software. > > Of course to complicate matters, in the longer term we're looking at > removing that constraint from pseries - but doing so will be dependent > on the guest kernel understanding a new format for the NUMA > information in the device tree. So qemu alone won't have enough > information to tell if such a configuration is possible or not.
Requiring both QEMU (and possibly management software) to be patched again after the guest kernel is fixed sounds undesirable. Perhaps a warning would be better in this case? In either case, it sounds like this won't be a common constraint and I now agree with your original suggestion of doing this in machine initialization code. -- Eduardo
