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. /mjt -- 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