git: 778488b9254b - stable/12 - man: document ether_gen_addr(9)

[Kevin Bowling]

The branch stable/12 has been updated by kbowling (ports committer):

URL: https://cgit.FreeBSD.org/src/commit/?id=778488b9254ba53e1a86e139f25df90fabe0784a

commit 778488b9254ba53e1a86e139f25df90fabe0784a
Author:     Kyle Evans <kevans at FreeBSD.org>
AuthorDate: 2021-04-16 01:08:27 +0000
Commit:     Kevin Bowling <kbowling at FreeBSD.org>
CommitDate: 2021-08-20 21:35:34 +0000

    man: document ether_gen_addr(9)
    
    This KPI is used to assign a MAC address to an interface that doesn't
    already have one assigned.
    
    Reviewed by:    bcr, gnn, imp, kbowling, kp
    MFC after:      3 days
    Differential Revision:  https://reviews.freebsd.org/D29787
    
    (cherry picked from commit e58a65ccdac352712e19a60fffa57a86afabbde9)
---
 share/man/man9/Makefile         |  1 +
 share/man/man9/ether_gen_addr.9 | 79 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 80 insertions(+)

diff --git a/share/man/man9/Makefile b/share/man/man9/Makefile
index 7a4fc64f5f88..ef9c1cc9c674 100644
--- a/share/man/man9/Makefile
+++ b/share/man/man9/Makefile
@@ -127,6 +127,7 @@ MAN=	accept_filter.9 \
 	DRIVER_MODULE.9 \
 	efirt.9 \
 	epoch.9 \
+	ether_gen_addr.9 \
 	EVENTHANDLER.9 \
 	eventtimers.9 \
 	extattr.9 \
diff --git a/share/man/man9/ether_gen_addr.9 b/share/man/man9/ether_gen_addr.9
new file mode 100644
index 000000000000..1b98a841736d
--- /dev/null
+++ b/share/man/man9/ether_gen_addr.9
@@ -0,0 +1,79 @@
+.\"
+.\" SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+.\"
+.\" Copyright (C) 2021 Kyle Evans <kevans at FreeBSD.org>
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice(s), this list of conditions and the following disclaimer as
+.\"    the first lines of this file unmodified other than the possible
+.\"    addition of one or more copyright notices.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice(s), this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
+.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+.\" DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
+.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+.\" DAMAGE.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd June 1, 2021
+.Dt ETHER_GEN_ADDR 9
+.Os
+.Sh NAME
+.Nm ether_gen_addr
+.Nd "generate an arbitrary MAC address for use"
+.Sh SYNOPSIS
+.In sys/types.h
+.In sys/socket.h
+.In net/if.h
+.In net/if_var.h
+.In net/ethernet.h
+.Ft void
+.Fn ether_gen_addr "struct ifnet *ifp" "struct ether_addr *hwaddr"
+.Sh DESCRIPTION
+The
+.Fn ether_gen_addr
+function generates an arbitrary MAC address for use by an ethernet interface
+that does not have an assigned address.
+.Pp
+By default,
+.Nm
+attempts to generate a stable MAC address using the hostid of the jail that
+the
+.Ar ifp
+is being added to.
+During early boot, the hostid may not be set on machines that haven't yet
+populated
+.Pa /etc/hostid ,
+or on machines that do not use
+.Xr loader 8 .
+.Pp
+.Nm
+can fail to derive a MAC address due to memory allocation failure.
+In this case, a locally-administered unicast MAC address will be randomly
+generated and returned via the
+.Ar hwaddr
+parameter.
+.Pp
+If
+.Nm
+succeeds, then it will return a MAC address in the FreeBSD Foundation OUI,
+.Dq 58:9c:fc ,
+via the
+.Ar hwaddr
+parameter.
+.Sh AUTHORS
+This manual page was written by
+.An Kyle Evans Aq Mt kevans at FreeBSD.org .