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Date:   Thu, 11 Feb 2021 11:45:12 +0100
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Joerg Vehlow <lkml@jv-coder.de>
Cc:     Miroslav Lichvar <mlichvar@redhat.com>, stable@vger.kernel.org,
        Ingo Molnar <mingo@kernel.org>,
        John Stultz <john.stultz@linaro.org>
Subject: Re: [4.14] Failing selftest timer/adjtick
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On Thu, Feb 11, 2021 at 11:33:05AM +0100, Joerg Vehlow wrote:
> Hi Miroslav,
> 
> On 2/10/2021 2:19 PM, Miroslav Lichvar wrote:
> > That patch cannot be applied alone. It would break the timekeeping in
> > not so obvious ways as there will be unexpected sources of the NTP
> > tracking error. IIRC, at least the following changes would need to be
> > included with it. There may be others.
> > 
> > c2cda2a5bda9 ("timekeeping/ntp: Don't align NTP frequency adjustments to ticks")
> > aea3706cfc4d ("timekeeping: Remove CONFIG_GENERIC_TIME_VSYSCALL_OLD")
> > d4d1fc61eb38 ("ia64: Update fsyscall gettime to use modern vsyscall_update")
> > 
> > My suggestion for a fix would be to increase the limit in the failing
> > test.
> Thanks, that's what I expected. But I still wonder why the test is failing
> almost 100% of time for me on qemu-arm64 (running on x86). Is this a
> regression in 4.14, that was working at some point or was it never tested on
> arm?

Does it work on a real system?  That's the proper test...