On Mon, Mar 25, 2013 at 11:44:30AM -0700, H. Peter Anvin wrote: > On 03/25/2013 08:15 AM, Igor Mammedov wrote: > >> > >> Such changes have been rejected in the past (e.g., n270 Atom). > >> I personally wouldn't object to 486 changes, but I guess it should > >> rather be handled via Igor's CPU static properties that I have in my > >> review queue: The .model value would be set to 8 but the PC machine > >> would be changed alongside to set model = 0 for pc-1.4 and earlier. > > It doesn't relates to property refactoring nor to slim CPU sub-classes > > conversion either. So it could go in independently. > > > > But is this change safe from migration POV? > > > > Well, given that the CPU model presented is actually closer to a model 8 > than a model 0 it probably is... but the real question is what would > cause someone to do migration of a 486 CPU model. > > The n270 issue is problematic, because right now "n270" can't actually > run software compiled for N270...
FWIW, I wouldn't mind too much if the maintainers decide to document 486 and n270 as "migration-unsafe" and then knowingly break live-migration of those CPU models between qemu <= 1.3 and qemu >= 1.4. It's up to the maintainers to choose which way to go. -- Eduardo
