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Date: Fri, 9 Mar 2007 10:00:49 -0800 (PST)
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Ingo Molnar <mingo@elte.hu>
cc: "Michael S. Tsirkin" <mst@mellanox.co.il>, Adrian Bunk <bunk@stusta.de>,
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Subject: Re: [2/6] 2.6.21-rc2: known regressions
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On Fri, 9 Mar 2007, Ingo Molnar wrote:
> > Some day we may have modesetting support in the kernel for some 
> > graphics hw, right now it's pretty damn spotty.
> 
> having no video is what i'd have expected - but getting a /hang/ is not 
> what i'd have expected.

I debugged a case exactly like this (with the TRACE_RESUME() thing) back 
last November on my laptop.

The problem is that radeonfb actually *tries* to re-initialize the 
graphics chips, but because it doesn't know all the details, it does it 
wrong, and hangs the whole chip.

I forget exactly where it happened, and it might well be different for 
you. But this is exactly what TRACE_RESUME can be used to pinpoint if you 
want to try to debug it. 

			Linus