xref: /freebsd/share/man/man9/devctl_notify.9 (revision fa9896e082a1046ff4fbc75fcba4d18d1f2efc19)
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24.Dd September 22, 2020
25.Dt DEVCTL_NOTIFY 9
26.Os
27.Sh NAME
28.Nm devctl_notify
29.Nd Send a message, via devctl, to userland
30.Sh SYNOPSIS
31.In sys/devctl.h
32.Ft void
33.Fn devctl_notify "const char *system" "const char *subsystem" "const char *type" "const char *data"
34.Sh DESCRIPTION
35Send a notification to user land via
36.Xr devctl 4 .
37See
38.Xr devctl 4
39for the format of these messages.
40.Pp
41The
42.Nm
43function creates a string using the following template:
44.Bd -literal
45snprintf(buffer, sizeof(buffer), "!system=%s subsystem=%s type=%s",
46   system, subsystem, type);
47.Ed
48.Pp
49The
50.Va system ,
51.Va subsystem ,
52and
53.Va type
54pointers cannot be NULL.
55.Pp
56The
57.Va data
58argument may be NULL (for no additions) or a message formatted
59properly for
60.Xr devctl 4 .
61A space will be added to the above template and this argument copied
62verbatim to form the message passed to userland.
63Senders should balance between only passing data that userland can not
64discover itself and sending all the data userland will want to use to
65decide what to do with the message.
66.Pp
67The current total message length limit is just under 1kb.
68Senders should try to remain well below this limit.
69.Sh SEE ALSO
70.Xr devctl 4 ,
71.Xr devd 8
72.Sh AUTHORS
73This manual page was written by
74.An M. Warner Losh
75