Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [RFC PATCH 06/13] m68k: Drop ARCH_USES_GETTIMEOFFSET
To:     Finn Thain <fthain@telegraphics.com.au>
Cc:     Geert Uytterhoeven <geert@linux-m68k.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Stephen N Chivers <schivers@csc.com.au>,
        Thomas Gleixner <tglx@linutronix.de>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        John Stultz <john.stultz@linaro.org>,
        linux-m68k <linux-m68k@lists.linux-m68k.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Philip Blundell <philb@gnu.org>,
        Joshua Thompson <funaho@jurai.org>
References: <cover.1541995959.git.fthain@telegraphics.com.au>
 <74edaee07800f91eb416ab3e72c4670b8ef4bd4e.1541995959.git.fthain@telegraphics.com.au>
 <CAMuHMdXdo+L-Ta04zUsL62RSt1HOvmPJs7HFu_zEnc38R0FPjA@mail.gmail.com>
 <alpine.LNX.2.21.1811122002530.351@nippy.intranet>
 <fb617c67-089b-c4c0-2f47-28db41ffca6c@gmail.com>
 <alpine.LNX.2.21.1811131413210.362@nippy.intranet>
 <b824e485-796c-cbb6-9e50-504b03accd5d@gmail.com>
 <alpine.LNX.2.21.1811131700010.366@nippy.intranet>
 <0054c37f-ef34-e892-ff1d-02968ab529fa@gmail.com>
 <alpine.LNX.2.21.1811140905440.371@nippy.intranet>
From:   Michael Schmitz <schmitzmic@gmail.com>
Message-ID: <73f75453-ce74-2c13-ba7c-f36f976d4ff7@gmail.com>
Date:   Wed, 14 Nov 2018 14:08:56 +1300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.2.1
MIME-Version: 1.0
In-Reply-To: <alpine.LNX.2.21.1811140905440.371@nippy.intranet>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 8bit
Content-Language: en-US
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Finn,

On 14/11/18 11:11 AM, Finn Thain wrote:
> On Tue, 13 Nov 2018, Michael Schmitz wrote:
>
>> Running a recent kernel under ARAnyM shows 40 ns resolution so the Atari
>> hardware emulation is a little more complete.
>>
> You mean, 40 us resolution, right?

Sorry, typo. Should have been us of course.

>
>> Using that for initial tests, I can confirm that timer resolution is
>> reduced to 10ms after patch 6, and gets restored to 40ns after applying
>> the full series
> Thanks for testing!
>
>> (once clocksource_init runs, that is - the first part of the boot is at
>> 10ms resolution only, a regression compared to with use of
>> arch_gettimeoffset).
>>
> Sounds like a theoretical regression (?)
>
> Is there any need for more precise timers (I mean, better than 40 us)
> before clocksource_init runs?

I don't think so, given that we can run just fine with 10 ms resolution.

>
>> Unfortunately, I can't log in at the console with all patches applied. I
>> immediately get the 'login timeout exceeded' message. Weird...
>>
> I didn't see that in my tests... Was this aranym or real hardware or both?

ARAnyM only so far.

>
> Can you also test tree fbf8405cd982 please?
>
My tests were on c606b5cf902 in case it wasn't clear. I've now seen 
fbf8405cd982, one moment please ...

That one does appear to work - different versions of ARAnyM, and 
different userland versions though. I'll test that again with the setup 
that saw c606b5cf902 fail.

Cheers,

     Michael