Re: kvm-78 - kernel panic after using system_reset except when using -no-kvm-irqchip

[Charles Duffy <Charles_Duffy@messageone.com>]

Jan Kiszka wrote:
> Charles Duffy wrote:
>> irq 25, desc: ffffffff803afc80, depth: 1, count: 0, unhandled: 0
>> ->handle_irq():  ffffffff800b54e3, handle_bad_irq+0x0/0x1f6
>> ->chip(): ffffffff802ea700, 0xffffffff802ea700
>> ->action(): 0000000000000000
>>   IRQ_DISABLED set
>> unexpected IRQ trap at vector 19
>> ..MP-BIOS bug: 8254 timer not connected to IO-APIC
>> timer doesn't work through the IO-APIC - disabling NMI Watchdog!
>> Kernel panic - not syncing: IO-APIC + timer doesn't work! Try using the
>> 'noapic' kernel parameter
> 
> Still too early for me, so I didn't get yet if you can trigger this
> guest panic reliably or only sporadically (like I can). In the former
> case I would be very interested in the how!

Reproduced 100% of the time when using system_reset at the qemu monitor 
console coming from a non-panic'd state. (Thus, it happens only every 
other time doing a series of boots and system_reset monitor commands).

> So far my theory on this is that the guest happens to loose too many PIC
> timer ticks during the test window where it checks the PIC IRQ routing
> (it does so with 10 ticks, out of which at least 4 must be delivered).
> The theory also says that this is hard to avoid, maybe just less likely
> with Gleb's timer drift compensation patches.
> 
> Jan
> 
> PS: Booting with noapic leaves many real boxes useless as well.
>