Messages in this thread | | | Subject | Re: i915 X lockup | From | Keith Packard <> | Date | Sat, 28 Feb 2009 09:11:58 -0800 |
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On Sat, 2009-02-28 at 00:47 -0800, Andrew Morton wrote:
> The kernel deadlocked on struct_mutex, did it not? That's a kernel bug > regardless of what userspace you're running.
No, it didn't deadlock on struct_mutex, it deadlocked because the hardware got wedged, and we still don't know how to unwedge the hardware and get it working again other than turning it off and back on again.
> Do we know why this happened?
Yes, the hardware will happily lock up when user space maps the PCI BAR covering the device registers and the application pokes various internal device registers directly.
That's the fundamental contract KMS requires -- if the kernel is going to manage the device, then user space isn't supposed to manipulate it directly anymore.
I suspect most any other device in the machine could be made to do 'bad things' if userspace went and poked it directly.
-- keith.packard@intel.com [unhandled content-type:application/pgp-signature] | |