V9FS

V9FS is a remote file system based on the 9P2000.L protocol.

Adding V9FS to the NuttX Configuration

The V9FS client is easy to add to your configuration. Just add CONFIG_FS_V9FS to nuttx/.config.

In order to fully run V9FS, you also need to select a transport layer driver. The two currently available are:

• VIRTIO -> CONFIG_V9FS_VIRTIO_9P=y
• SOCKET -> CONFIG_V9FS_SOCKET_9P=y

NFS Mount Command

In V9FS, we have some special parameters

• uname. Used to indicate the user identity of the client
• aname. Optional, it specifies the file tree that the client requests to access
• trans. Selects the transport layer (virtio/socket)
• msize. The maximum size of the message
• tag. The tag of the mount point

Different transport layers have different requirements for parameter passing. Here are some examples:

Qemu + VIRTIO

mount -t v9fs -o trans=virtio,tag=<mount_tag> /dir

Similarly, we need to bring the corresponding parameters in qemu

-fsdev local,security_model=none,id=fsdev1,path=<share-path> \
-device virtio-9p-device,id=fs1,fsdev=fsdev1,mount_tag=<mount_tag>

For how to start virtio-9p in QEMU, please refer to the document:

• https://wiki.qemu.org/Documentation/9psetup

Socket

mount -t v9fs -o trans=socket,tag=<IP Address>:[Port Default 563],aname=[path] /dir

There are many types of 9P socket servers. Here we use R9-fileserver (a cross-platform 9p server based on Rust https://github.com/crafcat7/R9-fileserver)

sudo ./ya-vm-file-server --network-address <IP Address>:<Server Port> --mount-point <share-path>

Result

NuttShell (NSH)
nsh> mkdir mnt
nsh> 
nsh> ls mnt
/mnt:
nsh> mount -t v9fs -o trans=virtio,tag=hostshare /mnt/v9fs
nsh> 
nsh> ls /mnt/v9fs
/mnt/v9fs:
sdcard/
mnt/
nsh> 
nsh> echo "This is a test" >/mnt/v9fs/testfile.txt
nsh> ls -l /mnt/v9fs
/mnt/v9fs:
drwxrwxrwx    1000    1000        4096 sdcard/
-rw-rw-rw-    1000    1000          15 testfile.txt
drwxrwxrwx    1000    1000        4096 mnt/
nsh> 
nsh> cat /mnt/v9fs/testfile.txt
This is a test
nsh>