DEVCTL_NOTIFY(9)       FreeBSD Kernel Developer's Manual      DEVCTL_NOTIFY(9)

NAME
     devctl_notify - Send a message, via devctl, to userland

SYNOPSIS
     #include <sys/devctl.h>

     void
     devctl_notify(const char *system, const char *subsystem,
         const char *type, const char *data);

DESCRIPTION
     Send a notification to user land via devctl(4).  See devctl(4) for the
     format of these messages.

     The devctl_notify function creates a string using the following template:

     snprintf(buffer, sizeof(buffer), "!system=%s subsystem=%s type=%s",
        system, subsystem, type);

     The system, subsystem, and type pointers cannot be NULL.

     The data argument may be NULL (for no additions) or a message formatted
     properly for 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.

     The current total message length limit is just under 1kb.  Senders should
     try to remain well below this limit.

SEE ALSO
     devctl(4), devd(8)

AUTHORS
     This manual page was written by M. Warner Losh

FreeBSD 13.1-RELEASE-p6       September 22, 2020       FreeBSD 13.1-RELEASE-p6