| ===================== | |
| 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. |