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Commit | Line | Data |
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17e0db82 SL |
1 | The CMA debugfs interface is useful to retrieve basic information out of the |
2 | different CMA areas and to test allocation/release in each of the areas. | |
3 | ||
4 | Each CMA zone represents a directory under <debugfs>/cma/, indexed by the | |
5 | kernel's CMA index. So the first CMA zone would be: | |
6 | ||
7 | <debugfs>/cma/cma-0 | |
8 | ||
9 | The structure of the files created under that directory is as follows: | |
10 | ||
11 | - [RO] base_pfn: The base PFN (Page Frame Number) of the zone. | |
12 | - [RO] count: Amount of memory in the CMA area. | |
13 | - [RO] order_per_bit: Order of pages represented by one bit. | |
14 | - [RO] bitmap: The bitmap of page states in the zone. | |
15 | - [WO] alloc: Allocate N pages from that CMA area. For example: | |
16 | ||
17 | echo 5 > <debugfs>/cma/cma-2/alloc | |
18 | ||
19 | would try to allocate 5 pages from the cma-2 area. | |
20 | ||
21 | - [WO] free: Free N pages from that CMA area, similar to the above. |