Messages in this thread | | | Date | Sun, 06 Sep 2020 11:00:37 +0100 | From | Marc Zyngier <> | Subject | Re: [PATCH v14 08/10] ptp: arm64: Enable ptp_kvm for arm64 |
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On Sat, 05 Sep 2020 12:01:42 +0100, Marc Zyngier <maz@kernel.org> wrote: > > On Fri, 04 Sep 2020 10:27:42 +0100, > Jianyong Wu <jianyong.wu@arm.com> wrote:
[...]
> > +{ > > + ktime_t ktime; > > + > > + arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID, > > + hvc_res); > > + if ((long long)(hvc_res->a0) < 0) > > + return -EOPNOTSUPP; > > Really? What if the cycle counter is a full 64 bit value, as it is > *mandated* on ARMv8.6? It means that the counter is now invalid for > half the lifetime of the system. Not acceptable either.
Having re-read this, this field doesn't contain the cycle counter, but the time in ns. So checking for a negative value should actually be fine for quite a while. My other comments still stand though.
Thanks,
M.
-- Without deviation from the norm, progress is not possible.
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