[Bug 96584] [regression] [i915] DMAR Errors Spamming Logs

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=96584

--- Comment #3 from Mike Lothian <mike at fireburn.co.uk> ---
Sorry I made a mistake in the last part of the bisect

The first broken commit is:

commit f7770bfd9fd2ef13a5b70de1ffbc16019a929b48
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date:   Sat May 14 07:26:35 2016 +0100

    drm/i915: Skip clearing the GGTT on full-ppgtt systems

    Under full-ppgtt, access to the global GTT is carefully regulated
    through hardware functions (i.e. userspace cannot read and write to
    arbitrary locations in the GGTT via the GPU). With this restriction in
    place, we can forgo clearing stale entries from the GGTT as they will
    not be accessed.

    For aliasing-ppgtt, we could almost do the same except that we do allow
    userspace access to the global-GTT via execbuf in order to workraound
    some quirks of certain instructions. (This execbuf path is filtered out
    with EINVAL on full-ppgtt.)

    The most dramatic effect this will have will be during resume, as with
    full-ppgtt the GGTT is only used sparingly.

    References: https://bugs.freedesktop.org/show_bug.cgi?id=94722
    Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
    Cc: David Weinehall <david.weinehall at intel.com>
    Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
    Tested-by: David Weinehall <david.weinehall at intel.com>
    Link:
http://patchwork.freedesktop.org/patch/msgid/1463207195-22076-4-git-send-email-chris@chris-wilson.co.uk

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