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061a785a11
Physical addresses under IOVA on x86 platform are mapped contiguously
as a side effect before the patch that removed CONFIG_DMA_REMAP. The
NTB rx buffer ring is a single chunk DMA buffer that is allocated
against the NTB PCI device. If the receive side is using a DMA device,
then the buffers are remapped against the DMA device before being
submitted via the dmaengine API. This scheme becomes a problem when
the physical memory is discontiguous. When dma_map_page() is called
on the kernel virtual address from the dma_alloc_coherent() call, the
new IOVA mapping no longer points to all the physical memory allocated
due to being discontiguous. Change dma_alloc_coherent() to dma_alloc_attrs()
in order to force DMA_ATTR_FORCE_CONTIGUOUS attribute. This is the best
fix for the circumstance. A potential future solution may be having the DMA
mapping API providing a way to alias an existing IOVA mapping to a new
device perhaps.
This fix is not to fix the patch pointed to by the fixes tag, but to fix
the issue arised in the ntb_transport driver on x86 platforms after the
said patch is applied.
Reported-by: Jerry Dai <jerry.dai@intel.com>
Fixes:
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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 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.