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This is a historical discription of what is now the kgsl backend
in libdrm freedreno (before the upstream drm/msm driver). Note
that the kgsl backend requires the "kgsl-drm" shim driver, which
usually is in disrepair (QCOM does not build it for android), and
due to random differences between different downstream android
kernel branches it may or may not work. So YMMV.
Original README:
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Note that current msm kernel driver is a bit strange. It provides a
DRM interface for GEM, which is basically sufficient to have DRI2
working. But it does not provide KMS. And interface to 2d and 3d
cores is via different other devices (/dev/kgsl-*). This is not
quite how I'd write a DRM driver, but at this stage it is useful for
xf86-video-freedreno and fdre (and eventual gallium driver) to be
able to work on existing kernel driver from QCOM, to allow to
capture cmdstream dumps from the binary blob drivers without having
to reboot. So libdrm_freedreno attempts to hide most of the crazy.
The intention is that when there is a proper kernel driver, it will
be mostly just changes in libdrm_freedreno to adapt the gallium
driver and xf86-video-freedreno (ignoring the fbdev->KMS changes).
So don't look at freedreno as an example of how to write a libdrm
module or a DRM driver.. it is just an attempt to paper over a non-
standard kernel driver architecture.
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