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2 CMA Debugfs Interface 2 CMA Debugfs Interface
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4 4
5 The CMA debugfs interface is useful to retriev 5 The CMA debugfs interface is useful to retrieve basic information out of the
6 different CMA areas and to test allocation/rel 6 different CMA areas and to test allocation/release in each of the areas.
7 7
8 Each CMA area represents a directory under <de 8 Each CMA area represents a directory under <debugfs>/cma/, represented by
9 its CMA name like below: 9 its CMA name like below:
10 10
11 <debugfs>/cma/<cma_name> 11 <debugfs>/cma/<cma_name>
12 12
13 The structure of the files created under that 13 The structure of the files created under that directory is as follows:
14 14
15 - [RO] base_pfn: The base PFN (Page Frame Num 15 - [RO] base_pfn: The base PFN (Page Frame Number) of the zone.
16 - [RO] count: Amount of memory in the CMA are 16 - [RO] count: Amount of memory in the CMA area.
17 - [RO] order_per_bit: Order of pages represen 17 - [RO] order_per_bit: Order of pages represented by one bit.
18 - [RO] bitmap: The bitmap of page states in t 18 - [RO] bitmap: The bitmap of page states in the zone.
19 - [WO] alloc: Allocate N pages from that CMA 19 - [WO] alloc: Allocate N pages from that CMA area. For example::
20 20
21 echo 5 > <debugfs>/cma/<cma_name>/allo 21 echo 5 > <debugfs>/cma/<cma_name>/alloc
22 22
23 would try to allocate 5 pages from the 'cma_na 23 would try to allocate 5 pages from the 'cma_name' area.
24 24
25 - [WO] free: Free N pages from that CMA area, 25 - [WO] free: Free N pages from that CMA area, similar to the above.
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