linux-sg2042/Documentation/ABI/testing/sysfs-kernel-iommu_groups

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What: /sys/kernel/iommu_groups/
Date: May 2012
KernelVersion: v3.5
Contact: Alex Williamson <alex.williamson@redhat.com>
Description: /sys/kernel/iommu_groups/ contains a number of sub-
directories, each representing an IOMMU group. The
name of the sub-directory matches the iommu_group_id()
for the group, which is an integer value. Within each
subdirectory is another directory named "devices" with
links to the sysfs devices contained in this group.
The group directory also optionally contains a "name"
file if the IOMMU driver has chosen to register a more
common name for the group.
Users:
What: /sys/kernel/iommu_groups/reserved_regions
Date: January 2017
KernelVersion: v4.11
Contact: Eric Auger <eric.auger@redhat.com>
Description: /sys/kernel/iommu_groups/reserved_regions list IOVA
regions that are reserved. Not necessarily all
reserved regions are listed. This is typically used to
output direct-mapped, MSI, non mappable regions. Each
region is described on a single line: the 1st field is
the base IOVA, the second is the end IOVA and the third
field describes the type of the region.
What: /sys/kernel/iommu_groups/reserved_regions
Date: June 2019
KernelVersion: v5.3
Contact: Eric Auger <eric.auger@redhat.com>
Description: In case an RMRR is used only by graphics or USB devices
it is now exposed as "direct-relaxable" instead of "direct".
In device assignment use case, for instance, those RMRR
are considered to be relaxable and safe.