On Thu, Jun 16, 2016 at 07:40:20PM +0200, Paolo Bonzini wrote: > > > On 16/06/2016 19:36, Eduardo Habkost wrote: > >> > > >> > Eduardo said nice for this part in previous version [1], so we may wait > >> > for his comments? > >> > > >> > [1] http://lists.nongnu.org/archive/html/qemu-devel/2016-06/msg01992.html > > I agree we don't need this check, but I still believe it is a > > nice thing to have. > > > > In addition to detecting user errors, they don't hurt and are > > useful for things like "-cpu host", that don't guarantee > > live-migration compatibility but still allow migration if you > > ensure host capabilities are the same on both sides. > > On the other hand we don't check for this on any other property, either > CPU or device, do we? Considering "lmce=on" always breaks on an old > kernel (i.e. there's no need for an explicit ",enforce" on the -cpu > flag), I think it's unnecessary and makes things inconsistent. BTW, just found another case where we check for migration mismatches: TSC frequency. if (env->tsc_khz && env->user_tsc_khz && env->tsc_khz != env->user_tsc_khz) { error_report("Mismatch between user-specified TSC frequency and " "migrated TSC frequency"); return -EINVAL; } We can do that because tsc_khz is unusual like mcg_cap: it can be configured by the user but is also included in the migration stream. -- Eduardo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
