diff options
| author | Sasha Levin | 2015-04-14 15:45:08 -0700 |
|---|---|---|
| committer | Linus Torvalds | 2015-04-14 16:49:00 -0700 |
| commit | 17e0db822b00cff96c1b662ac0dc0449cb70e0ec (patch) | |
| tree | b503c16809f9e83d63b59f834851660311ced95b /Documentation/cma | |
| parent | 875abdb6d43401c745ee8bc6d240f119a601d21f (diff) | |
cma: debug: document new debugfs interface
Document the structure and files under the new debugfs interface.
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/cma')
| -rw-r--r-- | Documentation/cma/debugfs.txt | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/Documentation/cma/debugfs.txt b/Documentation/cma/debugfs.txt new file mode 100644 index 000000000000..6cef20a8cedc --- /dev/null +++ b/Documentation/cma/debugfs.txt @@ -0,0 +1,21 @@ +The CMA debugfs interface is useful to retrieve basic information out of the +different CMA areas and to test allocation/release in each of the areas. + +Each CMA zone represents a directory under <debugfs>/cma/, indexed by the +kernel's CMA index. So the first CMA zone would be: + + <debugfs>/cma/cma-0 + +The structure of the files created under that directory is as follows: + + - [RO] base_pfn: The base PFN (Page Frame Number) of the zone. + - [RO] count: Amount of memory in the CMA area. + - [RO] order_per_bit: Order of pages represented by one bit. + - [RO] bitmap: The bitmap of page states in the zone. + - [WO] alloc: Allocate N pages from that CMA area. For example: + + echo 5 > <debugfs>/cma/cma-2/alloc + +would try to allocate 5 pages from the cma-2 area. + + - [WO] free: Free N pages from that CMA area, similar to the above. |