Re: [Xen-users] Debugging DomU

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Ian,

On 03/06/2015 10:28, Ian Campbell wrote:
> On Tue, 2015-06-02 at 22:46 +0000, Chris (Christopher) Brand wrote:
> > Hi Julien,
> >
> > > For DOMU, the timer frequency is retrieved from CNTFRQ_EL0.
> > > This register has to be setup correctly by the firmware/bootloader.
> > > Do you know if the timer node in the device tree for your platform has a property 
> > > "clock-frequency"? If yes, it will be very likely CNTFRQ_EL0 is not correctly 
> > > set.
> > It does indeed. I think I understand what's happening, then.
> > Bootloader is running only on core 0, and is setting CNTFRQ. When DomU
> > runs, its vcpu0 runs on a random physical core. If it happens to run
> > on core0, everything is fine. If it happens to run on any other core,
> > though, it fails because CNTFRQ is zero. So I need to ensure that
> > CNTFRQ is set for the other cores.
> Perhaps on secondary pCPU bring up Xen should check that either the
> clock frequency was overridden by the DT or that the new CPU's CNTFRQ
> says the same as the boot CPU?
I was thinking about the same. To add a warning if the "clock-frequency" 
property is checked and verifying that the CNTFRQ is not empty.
> Anyone care to send such a patch?
I will do it. I have another patch related to debug registers based on 
this thread too.
--
Julien Grall

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxx
http://lists.xen.org/xen-users