Messages in this thread | | | Subject | Re: [RFC 0/6] vDSO support for Hyper-V guest on ARM64 | From | Vincenzo Frascino <> | Date | Fri, 24 Jan 2020 10:24:44 +0000 |
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Hi Boqun Feng,
On 24/01/2020 06:32, Boqun Feng wrote: > Hi Vincenzo, >
[...]
>> >> I had a look to your patches and overall, I could not understand why we can't >> use the arch_timer to do the same things you are doing with the one you >> introduced in this series. What confuses me is that KVM works just fine with the >> arch_timer which was designed with virtualization in mind. Why do we need >> another one? Could you please explain? >> > > Please note that the guest VM on Hyper-V for ARM64 doesn't use > arch_timer as the clocksource. See: > > https://lore.kernel.org/linux-arm-kernel/1570129355-16005-7-git-send-email-mikelley@microsoft.com/ > > , ACPI_SIG_GTDT is used for setting up Hyper-V synthetic clocksource > and other initialization work. >
I had a look a look at it and my question stands, why do we need another timer on arm64?
> So just to be clear, your suggestion is > > 1) Hyper-V guest on ARM64 should use arch_timer as clocksource and vDSO > will just work. > > or > > 2) Even though arch_timer is not used as the clocksource, we can still > use it for vDSO. > > ? >
Option #1 would be the preferred solution, unless there is a good reason against.
> Regards, > Boqun >
-- Regards, Vincenzo [unhandled content-type:application/pgp-keys] | |