[Nouveau] [RFC PATCH v2 1/5] notify channel errors to userspace

[Alexandre Courbot]

On Mon, Aug 31, 2015 at 8:38 PM, Konsta Hölttä <kholtta at nvidia.com> wrote:
> Let userspace know about some specific types of errors via a shared
> buffer registered with a new ioctl, NOUVEAU_GEM_SET_ERROR_NOTIFIER.
> Once set, the notifier buffer is used until the channel is destroyed.
> The exceptional per-channel error conditions are signaled upwards from
> the nvkm layer via the event/notify mechanism and written to the buffer
> which holds the latest error occurred, readable from userspace.
>
> Some error situations render a channel completely stuck, which may
> require even discarding and reinitializing it or the gpu completely.
> Once a specific type of error happens, no others are expected until
> recovery. Passing the error to userspace in a shared buffer enables the
> graphics driver to periodically check in a light-weight way if anything
> went wrong (typically, after a submit); e.g., the GL robustness
> extension requires to detect that the context has dead.
>
> The notifier currently signals idle timeout, sw notify, mmu fault and
> illegal pbdma error conditions.

Hi Konsta,

Before this series can be considered for upstream, I suppose it will
need to be ported to the latest codebase.

This will likely require a rewrite due to the heavy changes that
occured, but hopefully it will also allow you to address some of the
hacks more cleanly.