On Fri, May 11, 2012 at 04:55:41PM -0600, Alex Williamson wrote: > IOMMU device groups are currently a rather vague associative notion > with assembly required by the user or user level driver provider to > do anything useful. This patch intends to grow the IOMMU group concept > into something a bit more consumable. > > To do this, we first create an object representing the group, struct > iommu_group. This structure is allocated (iommu_group_alloc) and > filled (iommu_group_add_device) by the iommu driver. The iommu driver > is free to add devices to the group using it's own set of policies. > This allows inclusion of devices based on physical hardware or topology > limitations of the platform, as well as soft requirements, such as > multi-function trust levels or peer-to-peer protection of the > interconnects. Each device may only belong to a single iommu group, > which is linked from struct device.iommu_group. IOMMU groups are > maintained using kobject reference counting, allowing for automatic > removal of empty, unreferenced groups. It is the responsibility of > the iommu driver to remove devices from the group > (iommu_group_remove_device). > > IOMMU groups also include a userspace representation in sysfs under > /sys/kernel/iommu_groups. When allocated, each group is given a > dynamically assign ID (int). The ID is managed by the core IOMMU group > code to support multiple heterogeneous iommu drivers, which could > potentially collide in group naming/numbering. This also keeps group > IDs to small, easily managed values. A directory is created under > /sys/kernel/iommu_groups for each group. A further subdirectory named > "devices" contains links to each device within the group. The iommu_group > file in the device's sysfs directory, which formerly contained a group > number when read, is now a link to the iommu group. Example: > > $ ls -l /sys/kernel/iommu_groups/26/devices/ <snip> As you are creating new sysfs files and directories, you need to also add the proper Documentation/ABI/ files at the same time. thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
