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Re: Kernel hang ...

To: Kanoj Sarcar <kanoj@xxxxxxxxxxxxxxxxxxx>
Subject: Re: Kernel hang ...
From: Ralf Baechle <ralf@xxxxxxxxxxx>
Date: Wed, 10 May 2000 20:12:36 +0200
Cc: linux-origin@xxxxxxxxxxx
In-reply-to: <200005101751.KAA05291@xxxxxxxxxxxxxxxxxxx>; from kanoj@xxxxxxxxxxxxxxxxxxx on Wed, May 10, 2000 at 10:51:41AM -0700
References: <20000510142407.A7547@xxxxxxxxxxxxxx> <200005101751.KAA05291@xxxxxxxxxxxxxxxxxxx>
Sender: owner-linux-origin@xxxxxxxxxxx
On Wed, May 10, 2000 at 10:51:41AM -0700, Kanoj Sarcar wrote:

> Depends on how you "disable" the other processors. Prom level disabling
> has not been tested at all, and I would suggest leaving that for a little
> later (maybe next week), since it also ties in to processor virtual/physical
> numbering. 
> 
> If you want to come up on a CONFIG_SMP kernel with just 1 processor,
> hack do_cpumask(), specifically, #if 0 out the code block
> 
>                         if (cpuid > *highest)
>                                 *highest = cpuid;
>                         /* Only let it join in if it's marked enabled */
>                         if (acpu->cpu_info.flags & KLINFO_ENABLE) {
>                                 CPUMASK_SETB(*boot_cpumask, cpuid);
>                                 cpus_found++;
>                         }

The machine actually freezes is the line

        if (maxcpus > 1) while(atomic_read(&numstarted) == 0);

In my case there is only a single enabled CPU, so the numstarted will
stay 0 and the kernel freezes.

With both CPUs enabled I get somewhat further, the kernel then freezes
after probing the caches.  Will take a look at this next.

  Ralf

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