diff options
| author | Yijie Yang <yijie.yang@oss.qualcomm.com> | 2026-08-11 16:46:47 +0800 |
|---|---|---|
| committer | Rob Herring (Arm) <robh@kernel.org> | 2026-08-15 15:46:52 -0500 |
| commit | e1c13aed4a1641550e8c9518c96f016e1d52d09b (patch) | |
| tree | 61c2297688373db165cc857b7c7adcb147a5c419 /Documentation/filesystems/devpts.rst | |
| download | linux-stable-e1c13aed4a1641550e8c9518c96f016e1d52d09b.tar.gz linux-stable-e1c13aed4a1641550e8c9518c96f016e1d52d09b.zip | |
dt-bindings: interconnect: qcom-bwmon: Add Maili cpu-bwmon compatiblegrafted
Add the Qualcomm Maili SoC compatible string for the CPU bandwidth
monitor (BWMONv4). This falls back to the sdm845-bwmon compatible,
consistent with the existing pattern used by other recent SoCs such as
sm8750 and kaanapali.
Signed-off-by: Yijie Yang <yijie.yang@oss.qualcomm.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Reviewed-by: Jingyi Wang <jingyi.wang@oss.qualcomm.com>
Link: https://patch.msgid.link/20260811-bwmon-v2-1-80f7f150ab9e@oss.qualcomm.com
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Diffstat (limited to 'Documentation/filesystems/devpts.rst')
| -rw-r--r-- | Documentation/filesystems/devpts.rst | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/Documentation/filesystems/devpts.rst b/Documentation/filesystems/devpts.rst new file mode 100644 index 000000000..b6324ab19 --- /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 indices allocated in one mount are independent from ptys +and their indices 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. |