[Proposal] Rocketchip Release 1.7

**Type of issue**: other enhancement

**Impact**: no functional change

**Development Phase**: proposal

**Other information**

Since rocket chip has been refactored to chisel3, and we have added the support of Zb/Zk extensions, I think it is possible to tag 4ecc497ccb72ff56a3bbeb07244a5545de8770d9 (or later commits) as v1.7

Start by reviewing commit 4ecc497ccb72ff56a3bbeb07244a5545de8770d9 and the subsequent Rocket Chip history to confirm the Chisel3 refactor and Zb/Zk support. Check the repository's existing release and tagging conventions before deciding whether v1.7 should point to that commit or a later one. Done means the release proposal is resolved and the agreed commit is tagged as v1.7.

Written by the indexing model from the issue text.