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So qxl has ioports, but it really really really doesn't want you
to write to them twice, but if you write and get a signal before
the irq arrives to let you know its completed, you have to think
ahead and avoid writing another time.
However this works fine for update area where really multiple
writes aren't the end of the world, however with create primary
surface, you can't ever do multiple writes. So this stop internal
kernel writes from doing interruptible waits, because otherwise
we have no idea if this write is a new one or a continuation of
a previous one.
virtual hw sucks more than real hw.
This fixes lockups and VM crashes when resizing and starting/stopping
X.
Signed-off-by: Dave Airlie <airlied@redhat.com>
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QXL is a paravirtual graphics device used by the Spice virtual desktop
interface.
The drivers uses GEM and TTM to manage memory, the qxl hw fencing however
is quite different than normal TTM expects, we have to keep track of a number
of non-linear fence ids per bo that we need to have released by the hardware.
The releases are freed from a workqueue that wakes up and processes the
release ring.
releases are suballocated from a BO, there are 3 release categories, drawables,
surfaces and cursor cmds. The hw also has 3 rings for commands, cursor and release handling.
The hardware also have a surface id tracking mechnaism and the driver encapsulates it completely inside the kernel, userspace never sees the actual hw surface
ids.
This requires a newer version of the QXL userspace driver, so shouldn't be
enabled until that has been placed into your distro of choice.
Authors: Dave Airlie, Alon Levy
v1.1: fixup some issues in the ioctl interface with padding
v1.2: add module device table
v1.3: fix nomodeset, fbcon leak, dumb bo create, release ring irq,
don't try flush release ring (broken hw), fix -modesetting.
v1.4: fbcon cpu usage reduction + suitable accel flags.
Signed-off-by: Alon Levy <alevy@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
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