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9199c070cd
Not too long ago, we realised we had issues with a rolling back a context so far for a preemption request we considered the resubmit not to be a rollback but a forward roll. This means we would issue a lite restore instead of forcing a full restore, continuing execution of the old requests rather than causing a preemption. Add a selftest to exercise such a far rollback, such that if we were to skip the full restore, we would execute invalid instructions in the ring and hang. Note that while I was able to confirm that this causes us to do a lite-restore preemption rollback (with commite36ba817fa("drm/i915/gt: Incrementally check for rewinding") disabled), it did not trick the HW into rolling past the old RING_TAIL. Myybe on other HW. References:e36ba817fa("drm/i915/gt: Incrementally check for rewinding") Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com> Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200616185518.11948-1-chris@chris-wilson.co.uk
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.