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01fd30da04
The new type struct dma_buf_map represents a mapping of dma-buf memory into kernel space. It contains a flag, is_iomem, that signals users to access the mapped memory with I/O operations instead of regular loads and stores. It was assumed that DMA buffer memory can be accessed with regular load and store operations. Some architectures, such as sparc64, require the use of I/O operations to access dma-map buffers that are located in I/O memory. Providing struct dma_buf_map allows drivers to implement this. This was specifically a problem when refreshing the graphics framebuffer on such systems. [1] As the first step, struct dma_buf stores an instance of struct dma_buf_map internally. Afterwards, dma-buf's vmap and vunmap interfaces are be converted. Finally, affected drivers can be fixed. v3: * moved documentation into separate patch * test for NULL pointers with !<ptr> [1] https://lore.kernel.org/dri-devel/20200725191012.GA434957@ravnborg.org/ Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> Reviewed-by: Christian König <christian.koenig@amd.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Acked-by: Sumit Semwal <sumit.semwal@linaro.org> Acked-by: Sam Ravnborg <sam@ravnborg.org> Link: https://patchwork.freedesktop.org/patch/msgid/20200925115601.23955-2-tzimmermann@suse.de |
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| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
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| net | ||
| samples | ||
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| sound | ||
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| usr | ||
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| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
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| .gitignore | ||
| .mailmap | ||
| COPYING | ||
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| README | ||
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 Restructured Text 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.