mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-08 12:52:40 -04:00
89461db349
When a reserved memory region described in the device tree is attached to a device, it is expected that the device's limitations are correctly included in that description. However, if the device driver failed to implement DMA address masking or addressing beyond the default 32 bits (on arm64), then bad things could happen because the DMA address was truncated, such as playing back audio with no actual audio coming out, or DMA overwriting random blocks of kernel memory. Check against the coherent DMA mask when the memory regions are attached to the device. Give a warning when the memory region can not be covered by the mask. A warning instead of a hard error was chosen, because it is possible that existing drivers could be working fine even if they forgot to extend the coherent DMA mask. Signed-off-by: Chen-Yu Tsai <wenst@chromium.org> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Link: https://lore.kernel.org/r/20250421083930.374173-1-wenst@chromium.org
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.