Re: [Xen-users] Debugging DomU

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

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?

Anyone care to send such a patch?

Ian.



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