> From: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx> > Sent: Wednesday, September 29, 2021 10:44 AM > > > One alternative option is to arrange device nodes in sub-directories based > > on the device type. But doing so also adds one trouble to userspace. The > > current vfio uAPI is designed to have the user query device type via > > VFIO_DEVICE_GET_INFO after opening the device. With this option the user > > instead needs to figure out the device type before opening the device, to > > identify the sub-directory. > > Wouldn't this be up to the operator / configuration, rather than the > actual software though? I would assume that typically the VFIO > program would be pointed at a specific vfio device node file to use, > e.g. > my-vfio-prog -d /dev/vfio/pci/0000:0a:03.1 > > Or more generally, if you're expecting userspace to know a name in a > uniqu pattern, they can equally well know a "type/name" pair. > You are correct. Currently: -device, vfio-pci,host=DDDD:BB:DD.F -device, vfio-pci,sysfdev=/sys/bus/pci/devices/ DDDD:BB:DD.F -device, vfio-platform,sysdev=/sys/bus/platform/devices/PNP0103:00 above is definitely type/name information to find the related node. Actually even for Jason's proposal we still need such information to identify the sysfs path. Then I feel type-based sub-directory does work. Adding another link to sysfs sounds unnecessary now. But I'm not sure whether we still want to create /dev/vfio/devices/vfio0 thing and related udev rule thing that you pointed out in another mail. Jason? Thanks Kevin
