On Monday, 06.07.2015 at 17:00, Antti Kantee wrote: > On 06/07/15 16:50, Martin Lucina wrote: > >On Monday, 06.07.2015 at 16:41, Antti Kantee wrote: > >>On 06/07/15 14:43, Martin Lucina wrote: > >>>I have also put in a check that warns if the "TSC invariant" bit is not set > >>>in CPUID, however it turns out that neither KVM nor QEMU set this on my > >>>system, possibly on purpose. So halting if that flag is not set would not > >>>be very useful :-/ > >> > >>Doesn't QEMU set the flags based on which cpu you tell it to > >>emulate? Or are you saying the flag is stripped even if the host cpu > >>sets it and -cpu host is used? > > > >The latter. It seems there's some work happened recently-ish regarding > >this. Under "KVM" in http://wiki.qemu.org/ChangeLog/2.1: > > > > New "invtsc" (Invariant TSC) CPU feature. When enabled, this will > > block migration and savevm, so it is not enabled by default on any CPU > > model. To enable invtsc, the migratable=no flag (supported only by -cpu > > host, by now) is required. So, invtsc is available only if using: -cpu > > host,migratable=no,+invtsc. > > > >I did try "-cpu host,migratable=no,+invtsc" on my machine but it doesn't > >make the warning go away... > > Silly question, but gotta ask it: is there a system where the > warning doesn't trigger?
Good catch. I had a bug in bmk_x86_cpuid(). Fixed, and the QEMU/KVM -cpu combo above now makes the warning go away. >
