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Add devctl_notify(9) man page

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Document the calls to send messages to userland via devctl.
devctl_notify will create a message for the specified system,
subsystem and type, optionally adding additional information.

Reviewed by: bcr
Differential Revision: https://reviews.freebsd.org/D26520
This commit is contained in:
Warner Losh 2020-09-22 23:02:01 +00:00
parent a5dca7c7e4
commit 6b1d211602
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1
share/man/man9/Makefile
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@ -121,6 +121,7 @@ MAN= accept_filter.9 \
DEVICE_SHUTDOWN.9 \
DEV_MODULE.9 \
dev_refthread.9 \
devctl_notify.9 \
devctl_process_running.9 \
devctl_safe_quote_sb.9 \
devctl_

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share/man/man9/devctl_notify.9 Normal file
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@ -0,0 +1,78 @@
.\"
.\" Copyright (c) 2020 M Warner Losh
.\"
.\" This program is free software.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd September 22, 2020
.Dt DEVCTL_NOTIFY 9
.Os
.Sh NAME
.Nm devctl_notify
.Nd Send a message, via devctl, to userland
.Sh SYNOPSIS
.In sys/devctl.h
.Ft void
.Fn devctl_notify "const char *system" "const char *subsystem" "const char *type" "const char *data"
.Sh DESCRIPTION
Send a notification to user land via
.Xr devctl 4 .
See
.Xr devctl 4
for the format of these messages.
.Pp
The
.Nm
function creates a string using the following template:
.Bd -literal
snprintf(buffer, sizeof(buffer), "!system=%s subsystem=%s type=%s",
system, subsystem, type);
.Ed
.Pp
The
.Va system ,
.Va subsystem ,
and
.Va type
pointers cannot be NULL.
.Pp
The
.Va data
argument may be NULL (for no additions) or a message formatted
properly for
.Xr devctl 4 .
A space will be added to the above template and this argument copied
verbatim to form the message passed to userland.
Senders should balance between only passing data that userland can not
discover itself and sending all the data userland will want to use to
decide what to do with the message.
.Pp
The current total message length limit is just under 1kb.
Senders should try to remain well below this limit.
.Sh SEE ALSO
.Xr devctl 4 ,
.Xr devd 8
.Sh AUTHORS
This manual page was written by
.An M. Warner Losh