On Fri, Nov 21, 2008 at 08:54:56AM +0100, Jan Kiszka wrote: > Eduardo Habkost wrote: > > On Thu, Nov 20, 2008 at 12:22:53PM -0200, Eduardo Habkost wrote: > >> Hi, > >> > >> When using a kvm.git kernel as host, I am getting guest boot failures > >> when booting Fedora Rawhide kernel (2.6.27.5-117.fc10.x86_64). Guest > >> stops booting at: > >> > >> ENABLING IO-APIC IRQs > >> ..TIMER: vector=0x30 apic1=0 pin1=0 apic2=-1 pin2=-1 > >> ..MP-BIOS bug: 8254 timer not connected to IO-APIC > >> ...trying to set up timer (IRQ0) through the 8259A ... > >> ..... (found apic 0 pin 0) ... > >> ....... failed. > >> ...trying to set up timer as Virtual Wire IRQ... > >> ..... failed. > >> ...trying to set up timer as ExtINT IRQ... > > > > I've just found out this problem happens because the guest has HZ=1000 > > and the host had HZ=250 and no CONFIG_HIGH_RES_TIMERS. > > > > With this setup, the host is not managing to inject enough timer > > interrupts during the mdelay() loop on timer_irq_works(). > > > > Interesting, and plausible. > > My observation so far is a sporadic test failure, often correlating with > some raised host OS load. I'm running a high-res kernel, but that cannot > prevent that this only 10 ticks long loop of the guest may obtain too > few CPU cycles to handle enough of them once in a while (IIRC, it needs > 4 out of the 10 ticks to declare the timer routing functional). > > Maybe Gleb's anti-coalesce patches for the PIC can also deal with your > timer resolution conflict. At least worth a try...
Aren't Gleb patches for the userspace PIT? I am seeing the problem here when using the in-kernel PIT, but (surprisingly) my setup works when using -no-kvm-pit. -- Eduardo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
