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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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