Michael, Following is some text that would need to be added to devpts section of mount(8) man page (its not a formal patch, just the text to be added). I am looking for logistics and a general review of the text to be added. The relevant kernel patches are currently in ttydev/linux-next trees. I can send the formal man page patch after those patches go into mainline. Also, is it ok to refer to 'Documentation' directory in the man page - there are several semantics outlined in Documentation/filesystem/devpts.txt (http://www.linux.org.uk/~alan/ttydev/pty-multiple-doc), that may be of use only to users of containers. Thanks, Suka --- --- devpts.manpage.orig 2008-11-26 10:04:11.000000000 -0800 +++ devpts.manpage 2008-11-26 10:02:15.000000000 -0800 @@ -1,3 +1,4 @@ + Mount options for devpts The devpts file system is a pseudo file system, traditionally mounted on /dev/pts. In order to acquire a pseudo terminal, a process opens @@ -17,3 +18,48 @@ default is 0600. A value of mode=620 and gid=5 makes "mesg y" the default on newly created PTYs. + newinstance + + Create a private instance of devpts filesystem, such that + indices of ptys allocated in this new instance of the + filesystem are independent of indices created in other + instances of devpts. + + If this option is not specified for a mount of devpts, + ("legacy mode"), that instance of devpts shares the pty + indices with the initial/default mount of devpts. i.e. + all mounts of devpts without this 'newinstance' option + share the same set of pty indices. Each mount of devpts + with newinstance option has a private set of pty indices. + + This option is mainly used to support containers in the + linux kernel. It is implemented in linux kernel versions + starting with 2.6.XX. Further, this mount option is valid + only if CONFIG_DEVPTS_MULTIPLE_INSTANCES is enabled in the + kernel configuration. + + To use this option effectively, '/dev/ptmx' must be a + symlink to 'pts/ptmx'. See Documentation/filesystems/ + devpts.txt for details. + + ptmxmode=value + + Set the mode for the new 'ptmx' device node in the devpts + filesystem. Default mode is 0000 for compatibility with + legacy mode of devpts. + + This option is only implemented in linux kernel versions + starting with 2.6.XX. Further this option is valid only if + CONFIG_DEVPTS_MULTIPLE_INSTANCES is enabled in the kernel + configuration. + + With support for multiple instances of devpts (see + 'newinstance' option above), each instance has a private + 'ptmx' node in the root of the devpts filesystem (typically + '/dev/pts/ptmx'). + + For compatibility with older versions of the kernel, the + default mode ot the new 'ptmx' node is 0000. 'ptmxmode' + option specifies a more useful mode for the 'ptmx' node + and is highly recommended when the 'newinstance' option + is specified. -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
