mnt(3) [plan9 man page]
MNT(3) Library Functions Manual MNT(3) NAME
mnt - attach to 9P servers SYNOPSIS
#M DESCRIPTION
The mount driver is used by the mount system call (but not bind; see bind(2)) to connect the name space of a process to the service pro- vided by a 9P server over a communications channel. After the mount, system calls involving files in that portion of the name space will be converted by the mount driver into the appropriate 9P messages to the server. The mount system call issues session and attach(5) messages to the server to identify and validate the user of the connection. Each dis- tinct user of a connection must mount it separately; the mount driver multiplexes the access of the various users and their processes to the service. File-oriented system calls are converted by the kernel into messages in the 9P protocol. Within the kernel, 9P is implemented by procedure calls to the various kernel device drivers. The mount driver translates these procedure calls into remote procedure calls to be transmit- ted as messages over the communication channel to the server. Each message is implemented by a write of the corresponding protocol message to the server channel followed by a read on the server channel to get the reply. Errors in the reply message are turned into system call error returns. A read(2) or write system call on a file served by the mount driver may be translated into more than one message, since there is a maximum data size for a 9P message. The system call will return when the specified number of bytes have been transferred or a short reply is returned. The string is an illegal file name, so this device can only be accessed directly by the kernel. SEE ALSO
bind(2) SOURCE
/sys/src/9/port/devmnt.c BUGS
When mounting a service through the mount driver, that is, when the channel being multiplexed is itself a file being served by the mount driver, large messages may be broken in two. MNT(3)
Check Out this Related Man Page
MQUEUEFS(5) BSD File Formats Manual MQUEUEFS(5) NAME
mqueuefs -- POSIX message queue file system SYNOPSIS
To link into kernel: options P1003_1B_MQUEUE To load as a kernel loadable module: kldload mqueuefs DESCRIPTION
The mqueuefs module will permit the FreeBSD kernel to support POSIX message queue. The module contains system calls to manipulate POSIX mes- sage queues. It also contains a file system to implement a view for all message queues of the system. This helps users to keep track of their message queues and make it more easily usable without having to invent additional tools. The most common usage is as follows: mount -t mqueuefs null /mnt/mqueue where /mnt/mqueue is a mount point. It is possible to define an entry in /etc/fstab that looks similar to: null /mnt/mqueue mqueuefs rw 0 0 This will mount mqueuefs at the /mnt/mqueue mount point during system boot. Using /mnt/mqueue as a permanent mount point is not advised as its intention has always been to be a temporary mount point. See hier(7) for more information on FreeBSD directory layout. Some common tools can be used on the file system, e.g.: cat(1), chmod(1), chown(8), ls(1), rm(1), etc. To use only the message queue system calls, it is not necessary for user to mount the file system, just load the module or compile it into the kernel. Manually creating a file, for example, ``touch /mnt/mqueue/myqueue'', will create a message queue named myqueue in the kernel, default message queue attributes will be applied to the queue. It is not advised to use this method to create a queue; it is better to use the mq_open(2) system call to create a queue as it allows the user to specify different attributes. To see the queue's attributes, just read the file: cat /mnt/mqueue/myqueue SEE ALSO
mq_open(2), nmount(2), unmount(2), mount(8), umount(8) AUTHORS
This manual page was written by David Xu <davidxu@FreeBSD.org>. BSD
November 30, 2005 BSD