• Chris Wilson's avatar
    drm/i915: Declare the swizzling unknown for L-shaped configurations · 5bc1d6f6
    Chris Wilson authored
    commit 5eb3e5a5 upstream.
    
    The old style of memory interleaving swizzled upto the end of the
    first even bank of memory, and then used the remainder as unswizzled on
    the unpaired bank - i.e. swizzling is not constant for all memory. This
    causes problems when we try to migrate memory and so the kernel prevents
    migration at all when we detect L-shaped inconsistent swizzling.
    However, this issue also extends to userspace who try to manually detile
    into memory as the swizzling for an individual page is unknown (it
    depends on its physical address only known to the kernel), userspace
    cannot correctly swizzle.
    
    Note that this is a new attempt for the previously merged one,
    reverted in
    
    commit d82c0ba6
    Author: Daniel Vetter <daniel.vetter@ffwll.ch>
    Date:   Tue Jul 14 12:29:27 2015 +0200
    
        Revert "drm/i915: Declare the swizzling unknown for L-shaped configurations"
    
    This is cc: stable since we need it to fix up troubles with wc cpu
    mmaps that userspace recently started to use widely.
    
    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91105Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
    Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
    [danvet: Add note about previous (failed attempt).]
    Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
    Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
    5bc1d6f6
i915_gem_tiling.c 17.1 KB