Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 17e0db82 authored by Sasha Levin's avatar Sasha Levin Committed by Linus Torvalds
Browse files

cma: debug: document new debugfs interface 



Document the structure and files under the new debugfs interface.

Signed-off-by: default avatarSasha 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 875abdb6

Documentation/cma/debugfs.txt

0 → 100644
+21 −0
Original line number Diff line number Diff line 
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.