I cannot get any CMA reserved space when I use latest LTS kernel (4.14): dmesg always says that no memory has been reserved for CMA.

 

Is CMA working on mainline kernel for Mali Midgard?

Is it required for 3D/video decoding stuff or the Mali kernel driver should instead allocate memory on-demand?

I see that most of the kernel configuration options regarding CMA are disable or not set, which one requires to be enabled?

 

I don't think this is "required" per se.

 

To reserve memory for the CMA allocator, you need to pass the cma=Size parameter to the kernel, at boot time.

Edit your boot file accordingly and add something like cma=32M .

Now this will reserve 32M of RAM for the CMA allocator. Meaning that, if it's not used, you'll just lose 32M of RAM for nothing.

Got it. Compiled my mainline kernel with various CMA configuration options on, got 16M of reserved CMA memory, but still have problems with userland mali libraries. I think I have to look elsewhere... but thanks in the meantime!

The most important feature for the Mali drivers is the DMABUF infrastructure.

 

Also, be sure to test the userland Mali drivers with the GBM/DRM OpenGL output before testing with the X11, since the X11 requires a very specific setup. glmark2 should help you in that regard.