Re: [Ksummit-discuss] [CORE TOPIC] Device error handling / reporting / isolation

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Wed, 2014-05-14 at 22:09 +0200, Daniel Vetter wrote:

> I'm not sure we really need to make a server/desktop disdinction here
> but more whether the driver (and all the stuff relying on it) care
> about data integrity all that much. With gpus we can forward such
> information to userspace and through some opengl extensions to
> applications, and the expectation is very much that if you want robust
> opengl, you need to be able to cope. The extension essentially tells
> you "oops, sorry something bad happened, please throw away all your
> gpu buffers".
> 
> Of course if a gpu reset does not fix the situation the driver should
> be able to tell the iommu to give up and fully isolate it. Also, to
> really make this work we'd need a way to tell the iommu to re-allow
> everything again and track faults again. Otherwise we can't tell
> whether the gpu reset worked in resolving the fault storm.

Right, though arguably in that context, doing an unconditional freeze
on error is still perfectly fine as long as the driver has the option
to unfreeze selectively.

Cheers,
Ben.