Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) =====================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) CMA Debugfs Interface
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3) =====================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5) The CMA debugfs interface is useful to retrieve basic information out of the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6) different CMA areas and to test allocation/release in each of the areas.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8) Each CMA zone represents a directory under <debugfs>/cma/, indexed by the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9) kernel's CMA index. So the first CMA zone would be:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) 	<debugfs>/cma/cma-0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) The structure of the files created under that directory is as follows:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15)  - [RO] base_pfn: The base PFN (Page Frame Number) of the zone.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16)  - [RO] count: Amount of memory in the CMA area.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17)  - [RO] order_per_bit: Order of pages represented by one bit.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18)  - [RO] bitmap: The bitmap of page states in the zone.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19)  - [WO] alloc: Allocate N pages from that CMA area. For example::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) 	echo 5 > <debugfs>/cma/cma-2/alloc
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) would try to allocate 5 pages from the cma-2 area.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25)  - [WO] free: Free N pages from that CMA area, similar to the above.