| ===================== |
| CMA Debugfs Interface |
| ===================== |
| |
| 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 area represents a directory under <debugfs>/cma/, represented by |
| its CMA name like below: |
| |
| <debugfs>/cma/<cma_name> |
| |
| The structure of the files created under that directory is as follows: |
| |
| - [RO] base_pfn: The base PFN (Page Frame Number) of the CMA area. |
| This is the same as ranges/0/base_pfn. |
| - [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 allocated pages in the area. |
| This is the same as ranges/0/base_pfn. |
| - [RO] ranges/N/base_pfn: The base PFN of contiguous range N |
| in the CMA area. |
| - [RO] ranges/N/bitmap: The bit map of allocated pages in |
| range N in the CMA area. |
| - [WO] alloc: Allocate N pages from that CMA area. For example:: |
| |
| echo 5 > <debugfs>/cma/<cma_name>/alloc |
| |
| would try to allocate 5 pages from the 'cma_name' area. |
| |
| - [WO] free: Free N pages from that CMA area, similar to the above. |
