openbsd 3.9 on Soekris 4801. - BSD

This is a discussion on openbsd 3.9 on Soekris 4801. - BSD ; I have just got a couple of soekris 4801 SBC, with OpenBSD installed. I am having a problem with the clock going slow. I find in the boot sequence, the following messages. OpenBSD 3.9 (GENERIC) #617: Thu Mar 2 02:26:48 ...

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Thread: openbsd 3.9 on Soekris 4801.

  1. openbsd 3.9 on Soekris 4801.

    I have just got a couple of soekris 4801 SBC, with OpenBSD installed.
    I am having a problem with the clock going slow. I find in the boot
    sequence, the following messages.

    OpenBSD 3.9 (GENERIC) #617: Thu Mar 2 02:26:48 MST 2006
    deraadt@i386.openbsd.org:/usr/src/sys/arch/i386/compile/GENERIC
    cpu0: Geode(TM) Integrated Processor by National Semi ("Geode by NSC"
    586-classz
    cpu0: FPU,TSC,MSR,CX8,CMOV,MMX
    cpu0: TSC disabled

    This last is worrying me as I need good time resolution and stability.

    Searching Google, I find to my dismay, that this processor is known
    to have a 'bug' or 'feature' which stops the TSC (and so affects the clock)
    when the CPU is idle. Does BSD disable the TSC on purpose? If so what
    if any clock is being used to keep time? The PIT, 27MHz? ..

    I suspect I am hitting suffering the consequences as even the use of ntp
    does not cure it.

    I have tried to heavily load the cpu's to see if that fixes it, but
    after an 8hr monitoring they are still losing time.
    example: The other is not so bad.
    30 May 20:46:30 ntpdate[18140]: step time server 192.168.1.2 offset
    -2.433104 sec
    30 May 20:49:50 ntpdate[24637]: step time server 192.168.1.2 offset
    -2.442288 sec
    30 May 21:50:31 ntpdate[22053]: step time server 192.168.1.2 offset
    -2.554892 sec

    Does anyone know if there are any BSD patches to fix/workaround this.
    Or, is there a knob to re-enable the TSC if that problem has been
    fixed by BSD. Bios or OS, I don't care.

    Linux patches are available to use the 27Mhz clock instead of the TSC
    I think. I haven't tried going back to linux..yet.

    Apologies, if this is possibly not the correct forum, but I couldn't
    find a dedicated soekris one.

    Thanks,
    Mike

  2. Re: openbsd 3.9 on Soekris 4801.

    mike wrote:
    > I have just got a couple of soekris 4801 SBC, with OpenBSD installed.
    > I am having a problem with the clock going slow. I find in the boot
    > sequence, the following messages.
    >
    > OpenBSD 3.9 (GENERIC) #617: Thu Mar 2 02:26:48 MST 2006
    > deraadt@i386.openbsd.org:/usr/src/sys/arch/i386/compile/GENERIC
    > cpu0: Geode(TM) Integrated Processor by National Semi ("Geode by NSC"
    > 586-classz
    > cpu0: FPU,TSC,MSR,CX8,CMOV,MMX
    > cpu0: TSC disabled
    >
    > This last is worrying me as I need good time resolution and stability.
    >
    > Searching Google, I find to my dismay, that this processor is known
    > to have a 'bug' or 'feature' which stops the TSC (and so affects the clock)
    > when the CPU is idle. Does BSD disable the TSC on purpose? If so what
    > if any clock is being used to keep time? The PIT, 27MHz? ..
    >
    > I suspect I am hitting suffering the consequences as even the use of ntp
    > does not cure it.
    >
    > I have tried to heavily load the cpu's to see if that fixes it, but
    > after an 8hr monitoring they are still losing time.
    > example: The other is not so bad.
    > 30 May 20:46:30 ntpdate[18140]: step time server 192.168.1.2 offset
    > -2.433104 sec
    > 30 May 20:49:50 ntpdate[24637]: step time server 192.168.1.2 offset
    > -2.442288 sec
    > 30 May 21:50:31 ntpdate[22053]: step time server 192.168.1.2 offset
    > -2.554892 sec
    >
    > Does anyone know if there are any BSD patches to fix/workaround this.
    > Or, is there a knob to re-enable the TSC if that problem has been
    > fixed by BSD. Bios or OS, I don't care.
    >
    > Linux patches are available to use the 27Mhz clock instead of the TSC
    > I think. I haven't tried going back to linux..yet.
    >
    > Apologies, if this is possibly not the correct forum, but I couldn't
    > find a dedicated soekris one.


    There is a Soekris-specific list, though I can't tell you where as I
    don't own a Soekris. You might get better answers there, though.

    As to NTP stability, what you see happens when the imprecision gets
    larger than what adjtime() can compensate for. This was, at one moment,
    'fixed' by Ted Unangst, as seen on
    http://marc.theaimsgroup.com/?l=open...306900483&w=2;
    however, this fix was apparently reverted a week later in when it was
    discovered that some ntpd implementations didn't like it.

    OpenNTPd - the stock NTPd - should be fine, though. You could ask
    tedu@openbsd.org if there are any plans to do something like the former
    commit, and if this would indeed solve your problems in an acceptable
    way.

    Since you're losing time, not dealing with a clock going too fast, a
    periodic reset using rdate from cron might work.

    Joachim

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