26 lines
981 B
ReStructuredText
26 lines
981 B
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
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==============================
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Allocating dma-buf using heaps
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==============================
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Dma-buf Heaps are a way for userspace to allocate dma-buf objects. They are
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typically used to allocate buffers from a specific allocation pool, or to share
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buffers across frameworks.
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Heaps
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=====
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A heap represents a specific allocator. The Linux kernel currently supports the
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following heaps:
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- The ``system`` heap allocates virtually contiguous, cacheable, buffers.
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- The ``cma`` heap allocates physically contiguous, cacheable,
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buffers. Only present if a CMA region is present. Such a region is
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usually created either through the kernel commandline through the
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`cma` parameter, a memory region Device-Tree node with the
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`linux,cma-default` property set, or through the `CMA_SIZE_MBYTES` or
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`CMA_SIZE_PERCENTAGE` Kconfig options. Depending on the platform, it
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might be called ``reserved``, ``linux,cma``, or ``default-pool``.
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