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SubjectRe: [PATCH v12 09/11] x86/tsc: prepare for early sched_clock
On Thu, 28 Jun 2018, Pavel Tatashin wrote:
> On Thu, Jun 28, 2018 at 11:23 AM Thomas Gleixner <tglx@linutronix.de> wrote:
> Hi Thomas,
>
> In addition to above, we have xen hvm:
>
> setup_arch()
> ...
> init_hypervisor_platform();
> x86_init.hyper.init_platform();
> xen_hvm_guest_init()
> xen_hvm_init_time_ops();

Duh. Missed that completely.

> ...
> tsc_early_delay_calibrate();
> tsc_khz = x86_platform.calibrate_tsc(); == xen_tsc_khz()
> ...
>
> Which works early.
>
> So, what should we do with xen, which seems to be the only platform
> that would provide different tsc frequency early and late, because of
> different calibration method?

Fix it? I have no idea why XEN has two variants of the scheme and I neither
have a clue why the KVM clock stuff is late.

Thanks,

tglx

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