Date: Thu, 09 Apr 2026 17:39:33 +0000 From: Baptiste Daroussin <bapt@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 72d701eb1d83 - main - nlsysevent: add manpage Message-ID: <69d7e455.32a5f.7dad4d3b@gitrepo.freebsd.org>
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The branch main has been updated by bapt: URL: https://cgit.FreeBSD.org/src/commit/?id=72d701eb1d83cfb3479e4c839412325ff9efc97c commit 72d701eb1d83cfb3479e4c839412325ff9efc97c Author: Baptiste Daroussin <bapt@FreeBSD.org> AuthorDate: 2026-04-09 08:50:41 +0000 Commit: Baptiste Daroussin <bapt@FreeBSD.org> CommitDate: 2026-04-09 17:39:28 +0000 nlsysevent: add manpage Reviewed by: des --- share/man/man4/Makefile | 1 + share/man/man4/nlsysevent.4 | 132 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 133 insertions(+) diff --git a/share/man/man4/Makefile b/share/man/man4/Makefile index c35859b30b60..6883cdd7d6cf 100644 --- a/share/man/man4/Makefile +++ b/share/man/man4/Makefile @@ -428,6 +428,7 @@ MAN= aac.4 \ ng_vjc.4 \ ng_vlan.4 \ ng_vlan_rotate.4 \ + nlsysevent.4 \ nmdm.4 \ ${_ntb.4} \ ${_ntb_hw_amd.4} \ diff --git a/share/man/man4/nlsysevent.4 b/share/man/man4/nlsysevent.4 new file mode 100644 index 000000000000..3b46ab65f568 --- /dev/null +++ b/share/man/man4/nlsysevent.4 @@ -0,0 +1,132 @@ +.\" +.\" Copyright (c) 2026 Baptiste Daroussin <bapt@FreeBSD.org> +.\" +.\" SPDX-License-Identifier: BSD-2-Clause +.\" +.Dd April 9, 2026 +.Dt NLSYSEVENT 4 +.Os +.Sh NAME +.Nm nlsysevent +.Nd Netlink-based kernel event notification module +.Sh SYNOPSIS +To load the driver as a module at boot time, place the following line in +.Xr loader.conf 5 : +.Bd -literal -offset indent +nlsysevent_load="YES" +.Ed +.Pp +Alternatively, to load the module at runtime: +.Bd -literal -offset indent +kldload nlsysevent +.Ed +.Sh DESCRIPTION +The +.Nm +kernel module provides a +.Xr netlink 4 +Generic Netlink interface for receiving kernel device events. +It hooks into the +.Xr devctl 4 +notification system and re-publishes all kernel events as Generic Netlink +multicast messages under the +.Dv NETLINK_GENERIC +protocol family. +.Pp +This provides an alternative to reading events from +.Pa /dev/devctl +.Pq used by Xr devd 8 , +with the advantage that multiple consumers can subscribe to events +simultaneously, and consumers can selectively subscribe to specific +event groups. +.Ss Generic Netlink Family +The module registers a Generic Netlink family named +.Dq Li nlsysevent . +The dynamically-assigned family identifier can be resolved using the +standard +.Dv CTRL_CMD_GETFAMILY +request as described in +.Xr genetlink 4 . +.Ss Commands +The following command is defined: +.Bl -tag -width indent +.It Dv NLSE_CMD_NEWEVENT +Sent when a kernel event occurs. +This message is never solicited by userland; it is only delivered to +sockets that have subscribed to one or more multicast groups. +.El +.Ss Attributes +Each +.Dv NLSE_CMD_NEWEVENT +message contains the following TLV attributes: +.Bl -tag -width indent +.It Dv NLSE_ATTR_SYSTEM +(string) The system name that generated the event +.Pq e.g., Dq Li ACPI , Dq Li IFNET , Dq Li USB . +.It Dv NLSE_ATTR_SUBSYSTEM +(string) The subsystem name within the system. +.It Dv NLSE_ATTR_TYPE +(string) The type of the event. +.It Dv NLSE_ATTR_DATA +(string) Optional extra data associated with the event. +This attribute may be absent if no extra data was provided. +.El +.Ss Multicast Groups +The module creates one multicast group per system name. +The following groups are pre-registered when the module is loaded: +.Pp +.Bl -column "HYPERV_NIC_VF" -offset indent -compact +.It Li ACPI +.It Li AEON +.It Li CAM +.It Li CARP +.It Li coretemp +.It Li DEVFS +.It Li device +.It Li ETHERNET +.It Li GEOM +.It Li HYPERV_NIC_VF +.It Li IFNET +.It Li INFINIBAND +.It Li KERNEL +.It Li nvme +.It Li PMU +.It Li RCTL +.It Li USB +.It Li VFS +.It Li VT +.It Li ZFS +.El +.Pp +Additional groups are created dynamically as new system names appear in +kernel events, up to a maximum of 64 groups. +.Pp +The group identifier for a given system name can be resolved via +.Dv CTRL_CMD_GETFAMILY +and then subscribed to using the +.Dv NETLINK_ADD_MEMBERSHIP +socket option. +.Sh EXAMPLES +The +.Xr genl 1 +utility can be used to monitor events: +.Bd -literal -offset indent +genl monitor nlsysevent +.Ed +.Sh SEE ALSO +.Xr genl 1 , +.Xr snl 3 , +.Xr devctl 4 , +.Xr genetlink 4 , +.Xr netlink 4 , +.Xr devd 8 +.Sh HISTORY +The +.Nm +module first appeared in +.Fx 15.0 . +.Sh AUTHORS +The +.Nm +kernel module and this manual page were written by +.An Baptiste Daroussin Aq Mt bapt@FreeBSD.org .home | help
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