4298780126
PCIe Process address space ID (PASID) is used to tag DMA traffic, it provides finer grained isolation than requester ID (RID). For each device/RID, 0 is a special PASID for the normal DMA (no PASID). This is universal across all architectures that supports PASID, therefore warranted to be reserved globally and declared in the common header. Consequently, we can avoid the conflict between different PASID use cases in the generic code. e.g. SVA and DMA API with PASIDs. This paved away for device drivers to choose global PASID policy while continue doing normal DMA. Noting that VT-d could support none-zero RID/NO_PASID, but currently not used. Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> Link: https://lore.kernel.org/r/20230802212427.1497170-2-jacob.jun.pan@linux.intel.com Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> Signed-off-by: Joerg Roedel <jroedel@suse.de>
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.