diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/admin-guide/sysctl/kernel.rst | 2 | ||||
| -rw-r--r-- | Documentation/filesystems/devpts.rst | 36 | ||||
| -rw-r--r-- | Documentation/filesystems/devpts.txt | 26 | ||||
| -rw-r--r-- | Documentation/filesystems/index.rst | 1 |
4 files changed, 38 insertions, 27 deletions
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index 82bfd5892663..706c2158ad25 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -895,7 +895,7 @@ this sysctl interface anymore. pty === -See Documentation/filesystems/devpts.txt. +See Documentation/filesystems/devpts.rst. randomize_va_space diff --git a/Documentation/filesystems/devpts.rst b/Documentation/filesystems/devpts.rst new file mode 100644 index 000000000000..a03248ddfb4c --- /dev/null +++ b/Documentation/filesystems/devpts.rst @@ -0,0 +1,36 @@ +.. SPDX-License-Identifier: GPL-2.0 + +===================== +The Devpts Filesystem +===================== + +Each mount of the devpts filesystem is now distinct such that ptys +and their indicies allocated in one mount are independent from ptys +and their indicies in all other mounts. + +All mounts of the devpts filesystem now create a ``/dev/pts/ptmx`` node +with permissions ``0000``. + +To retain backwards compatibility the a ptmx device node (aka any node +created with ``mknod name c 5 2``) when opened will look for an instance +of devpts under the name ``pts`` in the same directory as the ptmx device +node. + +As an option instead of placing a ``/dev/ptmx`` device node at ``/dev/ptmx`` +it is possible to place a symlink to ``/dev/pts/ptmx`` at ``/dev/ptmx`` or +to bind mount ``/dev/ptx/ptmx`` to ``/dev/ptmx``. If you opt for using +the devpts filesystem in this manner devpts should be mounted with +the ``ptmxmode=0666``, or ``chmod 0666 /dev/pts/ptmx`` should be called. + +Total count of pty pairs in all instances is limited by sysctls:: + + kernel.pty.max = 4096 - global limit + kernel.pty.reserve = 1024 - reserved for filesystems mounted from the initial mount namespace + kernel.pty.nr - current count of ptys + +Per-instance limit could be set by adding mount option ``max=<count>``. + +This feature was added in kernel 3.4 together with +``sysctl kernel.pty.reserve``. + +In kernels older than 3.4 sysctl ``kernel.pty.max`` works as per-instance limit. diff --git a/Documentation/filesystems/devpts.txt b/Documentation/filesystems/devpts.txt deleted file mode 100644 index 9f94fe276dea..000000000000 --- a/Documentation/filesystems/devpts.txt +++ /dev/null @@ -1,26 +0,0 @@ -Each mount of the devpts filesystem is now distinct such that ptys -and their indicies allocated in one mount are independent from ptys -and their indicies in all other mounts. - -All mounts of the devpts filesystem now create a /dev/pts/ptmx node -with permissions 0000. - -To retain backwards compatibility the a ptmx device node (aka any node -created with "mknod name c 5 2") when opened will look for an instance -of devpts under the name "pts" in the same directory as the ptmx device -node. - -As an option instead of placing a /dev/ptmx device node at /dev/ptmx -it is possible to place a symlink to /dev/pts/ptmx at /dev/ptmx or -to bind mount /dev/ptx/ptmx to /dev/ptmx. If you opt for using -the devpts filesystem in this manner devpts should be mounted with -the ptmxmode=0666, or chmod 0666 /dev/pts/ptmx should be called. - -Total count of pty pairs in all instances is limited by sysctls: -kernel.pty.max = 4096 - global limit -kernel.pty.reserve = 1024 - reserved for filesystems mounted from the initial mount namespace -kernel.pty.nr - current count of ptys - -Per-instance limit could be set by adding mount option "max=<count>". -This feature was added in kernel 3.4 together with sysctl kernel.pty.reserve. -In kernels older than 3.4 sysctl kernel.pty.max works as per-instance limit. diff --git a/Documentation/filesystems/index.rst b/Documentation/filesystems/index.rst index ec6e308587e1..43717f11d10b 100644 --- a/Documentation/filesystems/index.rst +++ b/Documentation/filesystems/index.rst @@ -24,6 +24,7 @@ algorithms work. splice locking directory-locking + devpts automount-support |