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SubjectRe: [08/36] AArch64: Kernel booting and initialisation
On 07/25/2012 04:47 AM, Catalin Marinas wrote:
> On Tue, Jul 24, 2012 at 08:42:28PM +0100, Christopher Covington wrote:
>> On 01/-10/-28163 02:59 PM, Catalin Marinas wrote:
>>> +- Architected timers
>>> + CNTFRQ must be programmed with the timer frequency.
>>> + If entering the kernel at EL1, CNTHCTL_EL2 must have EL1PCTEN (bit 0)
>>> + set where available.
>>
>> After Marc Zyngier's virtual timer patches come in, will the latter
>> requirement only be strictly necessary for kernels wanting to do
>> virtualization?
>
> A kernel is usually entered at EL1 (rather than EL2) if it is a guest.
> In this case, the EL1PCTEN bit should have been enabled from the higher
> level to give access to the physical counter.

Ah right, those patches still use the physical counter for the
clocksource and cyclecounter interfaces.

Thanks,
Christopher

--
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum


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