Re: [Qemu-devel] CentOS 5.x intermittently fails to boot on QEMU 1.7.0

[Alex Bligh]

On 22 Feb 2014, at 00:57, Matt Lupfer wrote:

> I did some more debugging and found the problem was elsewhere.  This
> different timer behavior is exposing a bug in the HPET implementation.
> 
> It's possible for the QEMU timer underlying the HPET to call the hpet_timer()
> callback between when the timer is created and when the HPET device is
> enabled (both actions initiated by the guest writing to HPET registers).
> When this happens, the QEMU timer is rearmed to an expiration
> time based on uninitialized values.  That's preventing the system timer
> interrupt from ticking in the guest during the timer check at boot.
> 
> The changes to the timer implementation just makes this a lot more likely
> to happen on CentOS 5.x kernels.

Thanks for debugging this. The timer changes for better or for worse
seem to be quite good at uncovering bugs elsewhere.

-- 
Alex Bligh