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207bbfb63d
For userptr bo with iommu on, multiple GPUs use same system memory dma mapping address when both adev and bo_adev are in identity mode or in the same iommu group. If RAM direct map to one GPU, other GPUs can share the original BO in order to reduce dma address array usage when RAM can direct map to these GPUs. However, we should explicit check whether RAM can direct map to all these GPUs. This patch fixes a potential issue that where RAM is direct mapped on some but not all GPUs. v2: 1. Update comment 2. Add helper function reuse_dmamap Signed-off-by: Shane Xiao <shane.xiao@amd.com> Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
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.