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Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/9p.rst | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/Documentation/filesystems/9p.rst b/Documentation/filesystems/9p.rst index 10cf79dc287f..2cc85f3e8659 100644 --- a/Documentation/filesystems/9p.rst +++ b/Documentation/filesystems/9p.rst @@ -67,6 +67,47 @@ To mount a 9p FS on a USB Host accessible via the gadget as root filesystem:: where <device> is the tag associated by the usb gadget transport. It is defined by the configfs instance name. +USBG Example +============ + +The USB host exports a filesystem, while the gadget on the USB device +side makes it mountable. + +Diod (9pfs server) and the forwarder are on the development host, where +the root filesystem is actually stored. The gadget is initialized during +boot (or later) on the embedded board. Then the forwarder will find it +on the USB bus and start forwarding requests. + +In this case the 9p requests come from the device and are handled by the +host. The reason is that USB device ports are normally not available on +PCs, so a connection in the other direction would not work. + +When using the usbg transport, for now there is no native usb host +service capable to handle the requests from the gadget driver. For +this we have to use the extra python tool p9_fwd.py from tools/usb. + +Just start the 9pfs capable network server like diod/nfs-ganesha e.g.: + + $ diod -f -n -d 0 -S -l 0.0.0.0:9999 -e $PWD + +Optionaly scan your bus if there are more then one usbg gadgets to find their path: + + $ python $kernel_dir/tools/usb/p9_fwd.py list + + Bus | Addr | Manufacturer | Product | ID | Path + --- | ---- | ---------------- | ---------------- | --------- | ---- + 2 | 67 | unknown | unknown | 1d6b:0109 | 2-1.1.2 + 2 | 68 | unknown | unknown | 1d6b:0109 | 2-1.1.3 + +Then start the python transport: + + $ python $kernel_dir/tools/usb/p9_fwd.py --path 2-1.1.2 connect -p 9999 + +After that the gadget driver can be used as described above. + +One use-case is to use it as an alternative to NFS root booting during +the development of embedded Linux devices. + Options ======= |