dhcpcd-discuss

Since SLAAC is handled by slaacd(8)[0], dhcpcd is only used for configuring DNS.

Specifically:

	$ sysctl -n kern.version
	OpenBSD 6.4-beta (GENERIC.MP) #300: Tue Sep 18 02:27:17 MDT 2018
	    deraadt@xxxxxxxxxxxxxxxxx:/usr/src/sys/arch/amd64/compile/GENERIC.MP
	
	$ dhcpcd --version
	dhcpcd 7.0.8
	Copyright (c) 2006-2018 Roy Marples
	Compiled in features: INET ARP ARPing IPv4LL INET6 DHCPv6 AUTH
	$ rcctl get dhcpcd flags
	trunk0
	$ cat /etc/dhcpcd.conf
	background
	persistent
	ipv6only
	ipv6ra_noautoconf
	option  domain_name domain_name_servers domain_search
	require domain_name_servers

slaacd configures IPs and dhcpcd successfully fills /etc/resolv.conf, but as a
negative side effect of `ipv6ra_noautoconf' the interface's AUTOCONF6 flag is
deconfigured as well:

	$ ifconfig trunk0 inet6 
	trunk0: flags=208943<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST,AUTOCONF6> mtu 1500
		lladdr 68:f7:28:89:4d:4d
		index 6 priority 0 llprio 3
		trunk: trunkproto failover
			trunkport iwm0 active
			trunkport em0 master
		groups: trunk egress
		media: Ethernet autoselect
		status: active
		inet6 fe80::d812:af1f:3f16:35aa%trunk0 prefixlen 64 scopeid 0x6
		inet6 fd00::73a9:9368:877:4da8 prefixlen 64 autoconf pltime 604100 vltime 2591300
		inet6 fd00::6e0e:2840:1717:1f8f prefixlen 64 autoconf autoconfprivacy pltime 71800 vltime 590451
		inet6 2001:xxxx:xxxx:1efd:c364:df18:f3b4:29b9 prefixlen 64 autoconf pltime 604100 vltime 2591300
		inet6 2001:xxxx:xxxx:1efd:f1d2:36ae:1034:f8d9 prefixlen 64 autoconf autoconfprivacy pltime 71661 vltime 590451
	# rcctl restart dhcpcd
	dhcpcd(ok)
	dhcpcd(ok)
	$ ifconfig trunk0 | head -n1
	trunk0: flags=8943<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500

As lifetimes run out and AUTOCONF6 is not set again unless manually with
`ifconfig trunk0 inet6 autoconf', slaacd stops configuring new addresses and I
eventually end up with all addresses being deprecated, hence no working uplink.

Is there some way to tell dhcpcd to handle only DNS and *not* touch the interface flag?

0:	http://man.openbsd.org/slaacd