Subject: Re: [BUG] 2.6.25-rc3-mm1 kernel panic while bootup on powerpc ()
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reply-To: benh@kernel.crashing.org
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Michael Neuling <mikey@neuling.org>, Matthew Wilcox <willy@debian.org>,
       linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org,
       Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
In-Reply-To: <20080304103350.12d26560.akpm@linux-foundation.org>
References: <20080304011928.e8c82c0c.akpm@linux-foundation.org>
	 <47CD4AB3.3080409@linux.vnet.ibm.com> <20778.1204641656@neuling.org>
	 <20080304103350.12d26560.akpm@linux-foundation.org>
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Date: Wed, 05 Mar 2008 19:23:40 +1100
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On Tue, 2008-03-04 at 10:33 -0800, Andrew Morton wrote:
> > Are we somehow enabling interrupts before we've setup
> ppc_md.get_irq?
> > 
> 
> Yes, we are - it's the semaphore rewrite which is doing this in
> start_kernel().  It's being discussed.
> 
> Enabling interrupts too early on powerpc was discovered to be fatal on
> powerpc years ago.  It looks like that remains the case.

Yes, it is and will probably always be. All that semaphore mucking
around that hard-enables interrupts is just asking for trouble (and on
more than just powerpc... heh, how do you do if your main interrupt
controller hasn't even been initialized yet ?)

Ben.


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