[igt-dev] [RFC] tests/i915/gem_exec_fence: Pre-fault objects with dependencies

[Chris Wilson]

Quoting Antonio Argenziano (2019-03-14 23:22:32)
> In the fault manager code we wait on an active object to complete before
> servicing the fault. This meant that the object 'out' used in the test
> could not be read until it became inactive which could not happen since
> it is kept busy from the store queued behind the spinner (at least). The
> bug became evident only after using the mmap_offset patches since we
> were not faulting before.

out is using mmap_wc, it doesn't block inside the fault handler today.
And it better had not start blocking in the future. Now for the opposite
problem of removing the gratuitous blocking in the gtt fault handler,
which may require some reminders to userspace that they needed to
control sync themselves.
-Chris