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1=====================2CMA Debugfs Interface3=====================4 5The CMA debugfs interface is useful to retrieve basic information out of the6different CMA areas and to test allocation/release in each of the areas.7 8Each CMA area represents a directory under <debugfs>/cma/, represented by9its 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 zone.16 - [RO] count: Amount of memory in the CMA area.17 - [RO] order_per_bit: Order of pages represented by one bit.18 - [RO] bitmap: The bitmap of page states in the zone.19 - [WO] alloc: Allocate N pages from that CMA area. For example::20 21 echo 5 > <debugfs>/cma/<cma_name>/alloc22 23would try to allocate 5 pages from the 'cma_name' area.24 25 - [WO] free: Free N pages from that CMA area, similar to the above.26