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config DRM_RADEON_KMS
bool "Enable modesetting on radeon by default - NEW DRIVER"
depends on DRM_RADEON
select BACKLIGHT_CLASS_DEVICE
help
Choose this option if you want kernel modesetting enabled by default.
This is a completely new driver. It's only part of the existing drm
for compatibility reasons. It requires an entirely different graphics
stack above it and works very differently from the old drm stack.
i.e. don't enable this unless you know what you are doing it may
cause issues or bugs compared to the previous userspace driver stack.
When kernel modesetting is enabled the IOCTL of radeon/drm
driver are considered as invalid and an error message is printed
in the log and they return failure.
KMS enabled userspace will use new API to talk with the radeon/drm
driver. The new API provide functions to create/destroy/share/mmap
buffer object which are then managed by the kernel memory manager
(here TTM). In order to submit command to the GPU the userspace
provide a buffer holding the command stream, along this buffer
userspace have to provide a list of buffer object used by the
command stream. The kernel radeon driver will then place buffer
in GPU accessible memory and will update command stream to reflect
the position of the different buffers.
The kernel will also perform security check on command stream
provided by the user, we want to catch and forbid any illegal use
of the GPU such as DMA into random system memory or into memory
not owned by the process supplying the command stream.
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