Index: ifconfig.c
===================================================================
RCS file: /cvs/src/sbin/ifconfig/ifconfig.c,v
retrieving revision 1.434
diff -u -p -r1.434 ifconfig.c
--- ifconfig.c	20 Feb 2021 01:17:45 -0000	1.434
+++ ifconfig.c	15 Mar 2021 06:11:51 -0000
@@ -270,6 +270,7 @@ void	unsettrunkport(const char *, int);
 void	settrunkproto(const char *, int);
 void	settrunklacpmode(const char *, int);
 void	settrunklacptimeout(const char *, int);
+void	linkwait(const char *, int);
 void	trunk_status(void);
 void	list_cloners(void);
 
@@ -667,6 +668,7 @@ const struct	cmd {
 	{ "inst",	NEXTARG,	A_MEDIAINST,	setmediainst },
 	{ "lladdr",	NEXTARG,	0,		setiflladdr },
 	{ "llprio",	NEXTARG,	0,		setifllprio },
+	{ "linkwait",	NEXTARG,	0,		linkwait },
 	{ NULL, /*src*/	0,		0,		setifaddr },
 	{ NULL, /*dst*/	0,		0,		setifdstaddr },
 	{ NULL, /*illegal*/0,		0,		NULL },
@@ -6685,6 +6675,38 @@ setiflladdr(const char *addr, int param)
 	bcopy(eap, ifr.ifr_addr.sa_data, ETHER_ADDR_LEN);
 	if (ioctl(sock, SIOCSIFLLADDR, (caddr_t)&ifr) == -1)
 		warn("SIOCSIFLLADDR");
+}
+
+void
+linkwait(const char *arg, int param)
+{
+	int waittime;
+	const char *errstr;
+	struct if_data ifrdat;
+
+	waittime = strtonum(arg, 1, 120, &errstr);
+	if (errstr != NULL)
+		errx(1, "%s wait time %s: %s", ifname, arg, errstr);
+
+	for (;;) {
+		memset(&ifr, 0, sizeof(ifr));
+		memset(&ifrdat, 0, sizeof(ifrdat));
+
+		strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
+		ifr.ifr_data = (caddr_t)&ifrdat;
+		if (ioctl(sock, SIOCGIFDATA, (caddr_t)&ifr) == -1)
+			err(1, "%s SIOCGIFDATA", ifname);
+
+		if (LINK_STATE_IS_UP(ifrdat.ifi_link_state))
+			return;
+
+		if (waittime-- == 0)
+			break;
+
+		sleep(1);
+	}
+
+	errx(1, "%s link wait time expired", ifname);
 }
 
 #ifndef SMALL
Index: ifconfig.8
===================================================================
RCS file: /cvs/src/sbin/ifconfig/ifconfig.8,v
retrieving revision 1.362
diff -u -p -r1.362 ifconfig.8
--- ifconfig.8	20 Feb 2021 01:21:04 -0000	1.362
+++ ifconfig.8	15 Mar 2021 06:11:51 -0000
@@ -344,6 +344,11 @@ of this is to select the connector type 
 Refer to the man page for the specific driver for more information.
 .It Cm -link[0-2]
 Disable special processing at the link level with the specified interface.
+.It Cm linkwait Ar seconds
+Wait up to the specific number of seconds for the link to come up.
+The range of valid
+.Ar seconds
+values is between 1 and 120.
 .It Cm lladdr Ar etheraddr Ns | Ns Cm random
 Change the link layer address (MAC address) of the interface.
 This should be specified as six colon-separated hex values, or can