0001 =====================
0002 CMA Debugfs Interface
0003 =====================
0004
0005 The CMA debugfs interface is useful to retrieve basic information out of the
0006 different CMA areas and to test allocation/release in each of the areas.
0007
0008 Each CMA zone represents a directory under <debugfs>/cma/, indexed by the
0009 kernel's CMA index. So the first CMA zone would be:
0010
0011 <debugfs>/cma/cma-0
0012
0013 The structure of the files created under that directory is as follows:
0014
0015 - [RO] base_pfn: The base PFN (Page Frame Number) of the zone.
0016 - [RO] count: Amount of memory in the CMA area.
0017 - [RO] order_per_bit: Order of pages represented by one bit.
0018 - [RO] bitmap: The bitmap of page states in the zone.
0019 - [WO] alloc: Allocate N pages from that CMA area. For example::
0020
0021 echo 5 > <debugfs>/cma/cma-2/alloc
0022
0023 would try to allocate 5 pages from the cma-2 area.
0024
0025 - [WO] free: Free N pages from that CMA area, similar to the above.
