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Maxime Ripard 4f5f8baf73 dma-buf: heaps: cma: Create CMA heap for each CMA reserved region
Aside from the main CMA region, it can be useful to allow userspace to
allocate from the other CMA reserved regions.

Indeed, those regions can have specific properties that can be useful to
a specific us-case.

For example, one of them platform I've been with has ECC enabled on the
entire memory but for a specific region. Using that region to allocate
framebuffers can be particular beneficial because enabling the ECC has a
performance and memory footprint cost.

Thus, exposing these regions as heaps user-space can allocate from and
import wherever needed allows to cover that use-case.

For now, only shared-dma-pools regions with the reusable property (ie,
backed by CMA) are supported, but eventually we'll want to support other
DMA pools types.

Since we collected all the CMA regions created during boot, we can
simply iterate over all of them to create the heaps.

This has a weird interaction with the recent work on the CMA name, in
particular the backward compatibility code created by commit
854acbe75f ("dma-buf: heaps: Give default CMA heap a fixed name").

Indeed, the old name was either 'reserved', or the name of the
reserved-memory region device tree node if the linux,cma-default
property was set.

In both these cases, we have now collected this region during boot, and
we're using the same name. So we're now largely redundant with the
code to handle backward compatibility code, and we can thus remove it
and the associated Kconfig option.

Reviewed-by: T.J. Mercier <tjmercier@google.com>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
   [sumits: rebased the doc to latest]
Link: https://lore.kernel.org/r/20251013-dma-buf-ecc-heap-v8-5-04ce150ea3d9@kernel.org
2025-10-18 21:31:22 +05:30
arch Kbuild fixes for 6.18 #1 2025-10-11 15:47:12 -07:00
block block-6.18-20251009 2025-10-10 10:37:13 -07:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto This push contains the following changes: 2025-10-10 08:56:16 -07:00
Documentation dma-buf: heaps: cma: Create CMA heap for each CMA reserved region 2025-10-18 21:31:22 +05:30
drivers dma-buf: heaps: cma: Create CMA heap for each CMA reserved region 2025-10-18 21:31:22 +05:30
fs - Avoid -Wflex-array-member-not-at-end warnings 2025-10-10 14:06:02 -07:00
include dma-buf: heaps: cma: Register list of CMA regions at boot 2025-10-18 21:31:21 +05:30
init printk changes for 6.18 2025-10-04 11:13:11 -07:00
io_uring io_uring/zcrx: increment fallback loop src offset 2025-10-08 07:26:14 -06:00
ipc namespace-6.18-rc1 2025-09-29 11:20:29 -07:00
kernel dma: contiguous: Reserve default CMA heap 2025-10-18 21:31:21 +05:30
lib lib/test_kho: use kho_preserve_vmalloc instead of storing addresses in fdt 2025-10-07 13:48:56 -07:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
mm slab hotfix for 6.18-rc1 2025-10-11 10:40:24 -07:00
net bpf-fixes 2025-10-11 10:31:38 -07:00
rust 7 hotfixes. All 7 are cc:stable and all 7 are for MM. 2025-10-11 10:14:55 -07:00
samples Char/Misc/IIO/Binder changes for 6.18-rc1 2025-10-04 16:26:32 -07:00
scripts Kbuild fixes for 6.18 #1 2025-10-11 15:47:12 -07:00
security integrity-v6.18 2025-10-05 10:48:33 -07:00
sound sound fixes for 6.18-rc1 2025-10-10 09:55:19 -07:00
tools - Remove a bunch of asm implementing condition flags testing in KVM's 2025-10-11 11:19:16 -07:00
usr gen_init_cpio: Ignore fsync() returning EINVAL on pipes 2025-10-07 09:53:05 -07:00
virt hyperv-next for v6.18 2025-10-07 08:40:15 -07:00
.clang-format Merge drm/drm-next into drm-misc-next 2025-10-13 09:19:19 +02:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: remove Alyssa Rosenzweig 2025-09-18 21:17:31 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore .gitignore: ignore compile_commands.json globally 2025-08-12 15:53:55 -07:00
.mailmap MAINTAINERS, .mailmap: update Umang's email address 2025-10-07 13:48:55 -07:00
.pylintrc tools: docs: parse-headers.py: move it from sphinx dir 2025-08-29 15:54:42 -06:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS USB/Thunderbolt changes for 6.18-rc1 2025-10-04 16:07:08 -07:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS dma-buf: heaps: cma: Register list of CMA regions at boot 2025-10-18 21:31:21 +05:30
Makefile Linux 6.18-rc1 2025-10-12 13:42:36 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.