The i915 Kernel module has several "module options" like the infamous enable_rc6.

However, for the xorg config file, there are further options such as TearFree.

I was wondering - why are there two ways to (seemingly?) set options the same module? Why can't I pass the TearFree option to the kernel module? Is this a general case and true for many other modules as well?

Any link to a good explanation is welcome!

1 Answer 1


Because they're two different drivers: the kernel driver and the xorg driver and each driver has its own, specific options.
The i915 kernel driver talks to the hardware device (it does basic, low level stuff like set up resolution, map a framebuffer etc).
The xorg intel driver includes OpenGL, DRI, DDX etc for 2D/3D acceleration and communicates with the gpu via the kernel module. In fact, the i915 kconfig even says

This driver is used by the Intel driver in X.org 6.8 and XFree86 4.4 and above

Further reading:
The Linux Graphics Stack

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