-.\" $OpenBSD: kstat.4,v 1.4 2022/01/10 10:20:31 dlg Exp $
+.\" $OpenBSD: kstat.4,v 1.5 2022/01/10 10:54:54 dlg Exp $
.\"
.\" Copyright (c) 2022 Jonathan Gray <jsg@openbsd.org>
.\"
flag in
.Va ks_rflags .
.Pp
+A kstat is identified by a 64bit number, or the combination of a
+provider name, unit number, name, and unit number.
+Upon the successful request of a kstat, the
+.Nm
+driver will update the
+.Vt kstat_req
+structure with current information.
+.\" list the struct members taht get updated and what they mean?
+.Pp
+Unless
+.Va ks_data
+is
+.Dv NULL ,
+the kstat subsystem will request an update of the statistics data
+and copy up to
+.Va ks_datalen
+bytes of it to the specified memory.
+.Pp
The kstat
.Xr ioctl 2
calls are as follows: