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