Greg Kroah-Hartman
598cf27219
Link: https://lore.kernel.org/r/20260217200002.683975158@linuxfoundation.org Tested-by: Florian Fainelli <florian.fainelli@broadcom.com> Tested-by: Takeshi Ogasawara <takeshi.ogasawara@futuring-girl.com> Tested-by: Peter Schneider <pschneider1968@googlemail.com> Tested-by: Jon Hunter <jonathanh@nvidia.com> Tested-by: Salvatore Bonaccorso <carnil@debian.org> Tested-by: Brett A C Sheffield <bacs@librecast.net> Tested-by: Mark Brown <broonie@kernel.org> Tested-by: Luna Jernberg <droidbittin@gmail.com> Tested-by: Ronald Warsow <rwarsow@gmx.de> Tested-by: Justin M. Forbes <jforbes@fedoraproject.org> Tested-by: Ron Economos <re@w6rz.net> Tested-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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=====================
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CMA Debugfs Interface
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=====================
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The CMA debugfs interface is useful to retrieve basic information out of the
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different CMA areas and to test allocation/release in each of the areas.
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Each CMA area represents a directory under <debugfs>/cma/, represented by
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its CMA name like below:
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<debugfs>/cma/<cma_name>
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The structure of the files created under that directory is as follows:
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- [RO] base_pfn: The base PFN (Page Frame Number) of the CMA area.
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This is the same as ranges/0/base_pfn.
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- [RO] count: Amount of memory in the CMA area.
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- [RO] order_per_bit: Order of pages represented by one bit.
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- [RO] bitmap: The bitmap of allocated pages in the area.
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This is the same as ranges/0/base_pfn.
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- [RO] ranges/N/base_pfn: The base PFN of contiguous range N
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in the CMA area.
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- [RO] ranges/N/bitmap: The bit map of allocated pages in
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range N in the CMA area.
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- [WO] alloc: Allocate N pages from that CMA area. For example::
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echo 5 > <debugfs>/cma/<cma_name>/alloc
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would try to allocate 5 pages from the 'cma_name' area.
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- [WO] free: Free N pages from that CMA area, similar to the above.
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