devctl_notify9
Send a message, via devctl, to userland
Usage
#include <sys/devctl.h>
void
devctl_notify(const char *system, const char *subsystem, const char *type, const char *data);
Overview
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.
Releases
15 releases since FreeBSD 13.0-RELEASE; the text changed 1 time.