Following patch is for the mount(8) man page.
There was discussion about creating a new devpts(4) man page and/or
including these man pages in the kernel source tree. Not sure if
the process has started. If so, please point me to the source on
which I can base this patch.
If its not yet ready, should we add these options to mount(8) for now,
so they get carried forward when devpts(4) is created ?
---
From: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
Subject: [RFC][PATCH] Document newinstance and ptmxmode options in devpts
Support for multiple instances of devpts were included in 2.6.29-rc1.
Update man pages to document the new options. Additional details about
the new options are described in 'Documentation/filesystems/devpts.txt'
of kernel source tree.
Signed-off-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
---
Index: util-linux-ng-2.14/mount/mount.8
===================================================================
--- util-linux-ng-2.14.orig/mount/mount.8 2009-01-15 21:11:33.000000000 -0800
+++ util-linux-ng-2.14/mount/mount.8 2009-01-15 22:14:44.000000000 -0800
@@ -899,6 +899,66 @@
and
.B gid=5
makes "mesg y" the default on newly created PTYs.
+.TP
+\fBnewinstance
+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
+.B newinstance
+option share the same set of pty indices. Each mount of devpts
+with
+.B 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 2.6.29. Further, this mount option is valid
+only if CONFIG_DEVPTS_MULTIPLE_INSTANCES is enabled in the
+kernel configuration.
+
+To use this option effectively,
+.IR /dev/ptmx
+must be a symbolic link to
+.IR pts/ptmx.
+See
+.IR Documentation/filesystems/devpts.txt
+in the linux kernel source tree for details.
+.TP
+.BI ptmxmode= value
+
+Set the mode for the new
+.IR 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 2.6.29. 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
+.B newinstance
+option above), each instance has a private
+.IR ptmx
+node in the root of the devpts filesystem (typically
+.IR /dev/pts/ptmx).
+
+For compatibility with older versions of the kernel, the
+default mode ot the new
+.IR ptmx
+node is 0000.
+.BI ptmxmode= value
+specifies a more useful mode for the
+.IR ptmx
+node and is highly recommended when the
+.B newinstance
+option is specified.
.SH "Mount options for ext"
None.
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