mirror of
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2025-09-04 20:19:47 +08:00
2d38f5fe1a
Following a recent discussion at last Plumbers, John Stultz, Sumit Sewal, TJ Mercier and I came to an agreement that we should document what the dma-buf heaps names are expected to be, and what the buffers attributes you'll get should be documented. Let's create that doc to make sure those attributes and names are guaranteed going forward. Reviewed-by: T.J. Mercier <tjmercier@google.com> Signed-off-by: Maxime Ripard <mripard@kernel.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net> Link: https://lore.kernel.org/r/20250306135114.1943738-1-mripard@kernel.org
26 lines
981 B
ReStructuredText
26 lines
981 B
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
|
|
|
|
==============================
|
|
Allocating dma-buf using heaps
|
|
==============================
|
|
|
|
Dma-buf Heaps are a way for userspace to allocate dma-buf objects. They are
|
|
typically used to allocate buffers from a specific allocation pool, or to share
|
|
buffers across frameworks.
|
|
|
|
Heaps
|
|
=====
|
|
|
|
A heap represents a specific allocator. The Linux kernel currently supports the
|
|
following heaps:
|
|
|
|
- The ``system`` heap allocates virtually contiguous, cacheable, buffers.
|
|
|
|
- The ``cma`` heap allocates physically contiguous, cacheable,
|
|
buffers. Only present if a CMA region is present. Such a region is
|
|
usually created either through the kernel commandline through the
|
|
`cma` parameter, a memory region Device-Tree node with the
|
|
`linux,cma-default` property set, or through the `CMA_SIZE_MBYTES` or
|
|
`CMA_SIZE_PERCENTAGE` Kconfig options. Depending on the platform, it
|
|
might be called ``reserved``, ``linux,cma``, or ``default-pool``.
|