On 07/25/2012 02:12 PM, Stefano Stabellini wrote: > On Wed, 25 Jul 2012, Michael Tokarev wrote: >> Stefano, Paul, can you take a look please? >> >> https://bugs.launchpad.net/bugs/1021649 > > That is a very good bug triage that you did! > > However "main_loop_wait: block indefinitely" only increases the maximum > select timeout of QEMU's main_loop. > That mean that if one or more emulators have bugs and don't get > notifications correctly they might hang. > The reason why it only reproduces with nographic is that both sdl and vnc > introduce a gui_timer that wakes QEMU up every 30ms. > > So the question is: why is kernel_irqchip=on required to repro the bug? > It strikes me as a bug in kernel_irqchip that prevents QEMU from being > waken up when it should.
kernel_irqchip=on means that many guest timers and interrupt sources are removed from qemu and implemented in the kernel, so qemu sees a lot less wakeups and hangs. With kernel_irqchip=off the APIC or PIT wakes up qemu, taking the place of the keypress. -- error compiling committee.c: too many arguments to function
