On Fri, Aug 10, 2012 at 01:24:06PM +0400, Michael Tokarev wrote: > On 10.08.2012 11:33, Gleb Natapov wrote: > > On Thu, Aug 09, 2012 at 10:27:43PM +0400, Michael Tokarev wrote: > >> As a follow-up to the patch "tsc: use kvmclock for > >> calibration". > >> > >> There's another problem reported by several users. > >> The sympthom is that grub does not show boot menu, > >> it boots default entry right away without any pause. > >> > >> After quite some debugging it turned out to be > >> TSC issue. Grub uses tsc for its timeout handling. > >> When setting timeout to some very large value > >> (10000), I can see the counter is ticking backwards > >> at a very high speed, ticking from 10000 to 0 in > >> about 5 seconds. > >> > >> Running kvm -cpu host,-tsc forces grub to use > >> rtc clocksource, and the problem goes away. > >> > > Can you try -no-kvm-pit-reinjection please. > > It does not help. With -no-kvm-pit-reinjection, the > time in grub is ticking about 1000 times faster still, > just like without. > > >> The most interesting thing is that this is a > >> problem new for qemu-kvm 1.1 (and is still > >> present in current git), 1.0 version had no > >> such issue. And it only happens when in-kernel > >> irqchip is enabled -- running with -no-kvm-irqchip > >> also fixes the grub problem, so that tsc starts > >> counting "correctly" for grub again. > >> > > 1.0 work on the same kernel 1.1 doesn't? > > Yes. This issue does not look like kernel-dependent - > it happens the same way on 3.0, 3.2 and 3.5 kernels. > Note that upstream qemu 1.1+ is also affected, when > used with -machine pc,kernel_irqchip=on. > Any chance to bisect it? -- Gleb. -- 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
