1=====================
2CMA Debugfs Interface
3=====================
4
5The CMA debugfs interface is useful to retrieve basic information out of the
6different CMA areas and to test allocation/release in each of the areas.
7
8Each CMA area represents a directory under <debugfs>/cma/, represented by
9its CMA name like below:
10
11	<debugfs>/cma/<cma_name>
12
13The structure of the files created under that directory is as follows:
14
15 - [RO] base_pfn: The base PFN (Page Frame Number) of the CMA area.
16        This is the same as ranges/0/base_pfn.
17 - [RO] count: Amount of memory in the CMA area.
18 - [RO] order_per_bit: Order of pages represented by one bit.
19 - [RO] bitmap: The bitmap of allocated pages in the area.
20        This is the same as ranges/0/base_pfn.
21 - [RO] ranges/N/base_pfn: The base PFN of contiguous range N
22        in the CMA area.
23 - [RO] ranges/N/bitmap: The bit map of allocated pages in
24        range N in the CMA area.
25 - [WO] alloc: Allocate N pages from that CMA area. For example::
26
27	echo 5 > <debugfs>/cma/<cma_name>/alloc
28
29would try to allocate 5 pages from the 'cma_name' area.
30
31 - [WO] free: Free N pages from that CMA area, similar to the above.
32