Hi,
The memory buffers are allocated using the CMA (Continuous Memory Allocator). By default all devices allocate memory from the same pool or region. The size of this region is specified in the kernel config and currently is 128MB. Using the kernel command line it possible to override the location and size of this default region.
It is also possible to specify a specific memory region and assign this region to be exclusively used by one or more devices. These memory regions can be declared and assigned to a device in the devicetree using the reserved memory bindings.
- Lars