Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Tue, 11 May 2021 11:07:59 +0200 | Subject | Re: [PATCH v19 7/7] ptp: arm/arm64: Enable ptp_kvm for arm/arm64 |
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Hi Marc, Jianyong,
On Tue, Mar 30, 2021 at 4:56 PM Marc Zyngier <maz@kernel.org> wrote: > From: Jianyong Wu <jianyong.wu@arm.com> > > Currently, there is no mechanism to keep time sync between guest and host > in arm/arm64 virtualization environment. Time in guest will drift compared > with host after boot up as they may both use third party time sources > to correct their time respectively. The time deviation will be in order > of milliseconds. But in some scenarios,like in cloud environment, we ask > for higher time precision. > > kvm ptp clock, which chooses the host clock source as a reference > clock to sync time between guest and host, has been adopted by x86 > which takes the time sync order from milliseconds to nanoseconds. > > This patch enables kvm ptp clock for arm/arm64 and improves clock sync precision > significantly.
> --- a/drivers/ptp/Kconfig > +++ b/drivers/ptp/Kconfig > @@ -108,7 +108,7 @@ config PTP_1588_CLOCK_PCH > config PTP_1588_CLOCK_KVM > tristate "KVM virtual PTP clock" > depends on PTP_1588_CLOCK > - depends on KVM_GUEST && X86 > + depends on (KVM_GUEST && X86) || (HAVE_ARM_SMCCC_DISCOVERY && ARM_ARCH_TIMER)
Why does this not depend on KVM_GUEST on ARM? I.e. shouldn't the dependency be:
KVM_GUEST && (X86 || (HAVE_ARM_SMCCC_DISCOVERY && ARM_ARCH_TIMER))
?
> default y > help > This driver adds support for using kvm infrastructure as a PTP
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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