This tracks the relevant pieces of getting IPv6 support for guests. There is a bit of blocking work in OPTE which is mostly tracked in oxidecomputer/opte#10. I'll make more issues here as they come up, but for now the list is:

• Allocate a VPC-private IPv6 address for every guest NIC
• Support allocation of ephemeral IPv6 addresses out of a pool. This could be a big project. Indexing by IP type might work, or we may need to support only one IP version in any given IP Pool, or change the query / table structure in other ways to make this more efficient. This ties in with External IP allocation query needs some TLC #1468 and others.
• Need to re-check support for IPv6 Router and Firewall APIs
• Pull in latest OPTE changes to actually assign IPv6 data to guests