On Thu, Dec 16, 1999 at 06:21:54AM -0800, David S. Miller wrote:
> Date: Thu, 16 Dec 1999 09:14:07 -0500 (EST)
> From: Ingo Molnar <[EMAIL PROTECTED]>
>
> the 4-CPU box is up and running ever since removing those
> printk's. 3 weeks uptime and no SMP-specific problems. Any
> suggestion/patch to debug the printk problem is welcome.
>
> What you could do is somehow trace to the exact thing which
> causes the secondary processor to hang. You could do something
> clever like print dots on the serial console or real graphics
> console at strategic places, and keep jumbling them around until
> you determine the precise place.
Serial console is IMHO out of question for this as it is very timing
related.
I've always used leds for such debugging.
I've seen this specific problem once when I was hacking SMP on it, but
it magically went away and I could not reproduce it any more.
But I remember it was locking up on the irq safe console_lock in printk
if my leds were right and my memory serves well.
To debug things with leds one needs to uncomment led blinking in timer irq
handlers and use the macros prepared for it. The usage can be found in the
irq handlers e.g.
I'm sorry I cannot dig into this now because that machine is no longer under
my control. But AFAIK it runs 2.2.7 in SMP till now.
>
> Also Ingo, could you send me 'prtconf -pv' from the machine?
> I can use that to obtain CPU revision numbers and figure out
> if there is some hardware bug which needs a workaround which
> we have not implemented (some SuperSparc cpus have corrupted
> L2 cache contents when booted as secondary processors, we never
> have had opportunity to test a workaround so we never implemented
> it, so it might what we're hitting here).
They should be in prtconf examples I think.
Cheers,
Jakub
___________________________________________________________________
Jakub Jelinek | [EMAIL PROTECTED] | http://sunsite.mff.cuni.cz/~jj
Linux version 2.3.26 on a sparc64 machine (1343.49 BogoMips)
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