With IPv6, how to get both GUA SLAAC and a single ULA DHCPv6 address?

[espenu]

@espenu - I think I have found a close enough solution after a bit of trial and error.  I wanted a similar home setup with stable v6 and v4 addressing so win win!  I use unbound for resolution and forward local network DNS queries to DNSMASQ.  Here's the basic steps:

I've now finally had time to test and I can't get it to work as you describe.
Looking at the RA messages in Wireshark I can see RA's from both radvd and dnsmasq, and as long as one of them have "A=1" for the ULA prefix, the client will generate its own address in that prefix.

Note that also the only way I've managed to get Dnsmasq to send "A=0" is to enable "Router advertisements" under general and have nothing selected (Default) for RA mode in the DHCP range. The UI help states that "Setting Router Advertisement modes in DHCPv6 ranges will have no effect without this global option enabled.", but that's clearly not true, because setting anything in the DHCP range RA mode field will cause A=1.

Even if I get Dnsmasq to set M=1 and A=0 for the ULA prefix, radvd will come in and set A=1 for that same prefix. Turning radvd off for that interface will of course also mean no GUA SLAAC.

However, it works on your end, and I just don't understand how. Do you have any Wireshark logs of your RA messages that might help explain it?