Subject: Re: Make sure we populate the initroot filesystem late enough
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Woodhouse <dwmw2@infradead.org>, linuxppc-dev@ozlabs.org,
       LKML <linux-kernel@vger.kernel.org>, Milton Miller <miltonm@bga.com>
In-Reply-To: <Pine.LNX.4.64.0702261315080.12485@woody.linux-foundation.org>
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Date: Tue, 27 Feb 2007 07:46:39 +0100
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> USB controller issues? We used to have these really hard-to-debug problems 
> with the USB controller being active and having had the BIOS set up the 
> command queues etc. Really subtle. It's why we now have PCI quirks for 
> shutting up (most) USB controllers very early.

On powermacs or powerbooks, the USB controller is shut down by the
firmware when we call the "quiesce" OF call from prom_init.c, which
happens before the kernel relocates itself to 0 and takes over memory.
Unless we fucked up something in there, I wouldn't expect that to be the
cause.
 
> If there is some USB controller that we miss, or that sets up its command 
> chain to some unexpected area (so that USB is active and corrupting memory 
> even very early on), that could explain it.

Did we setup the OHCI controller when the crash happen ? Maybe we broke
something subtle in the USB stack ?

Ben.


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