Re: Kernel locks up after calling kernel_execve()

["Gerhard Pircher" <gerhard_pircher@gmx.net>]

-------- Original-Nachricht --------
> Datum: Wed, 14 Nov 2007 10:37:52 +1100
> Von: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> An: Gerhard Pircher <gerhard_pircher@gmx.net>
> CC: linuxppc-dev@ozlabs.org
> Betreff: Re: Kernel locks up after calling kernel_execve()

> Add printk's to things :-) It's a UP kernel so there should be no
> spinlocks anyway.
> 
> Best is to try to get a 100% reprocase and printk your way toward the
> origin of the problem if you don't have a HW debugger. Unless you manage
> to sneak in an irq to xmon but if you are totally locked up, you
> probably can't.
Also xmon seems to lockup the machine. I was able to active it through the
magic sysrq key, but the machine died afterwards.

> Could also be something you do that your buggy northbridge doesn't like.
> For example, maybe it dislikes M bit in the hash table and you end up
> with it set due to other reasons (I know we had changes in this area).
Yeah, the northbridge hates the M bit! Thus the AmigaOne platform code
masks out the CPU_FTR_NEED_COHERENT flag and disables the L2 cache
prefetch engines (I don't care about the performance loss).
I couldn't find any other code that sets the M bit, except for huge TLB
page support, but isn't that only for PPC64?

Gerhard
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