Booting from an FFS2 filesystem
Developer Otto Moerbeek (otto@) hasbeenworkingonsupporttobootfromFFS2. He writes in with the below article, to give us a little insight into the challenges he faced while working on this.
FFS2 filesystem support has been in OpenBSD for quite a while. FFS2has a few advantages above FFS1: large partition support, 64-bittimestamps, faster newfs(8) and faster fsck(8), but it is only usedfor large (> 1TB) filesystems at the moment. The only drawback is thatits meta-data overhead is a bit larger than FFS1 because of 64-bitinstead of 32-bit blocknumbers and timestamps.
I decided that it was time to start using FFS2 in as many places aspossible, and that includes booting from it. Booting is an area wherethere are quite large differences between the various platforms OpenBSDsupports. The boot code interacts with the platform-specific firmwareand the bootstrap process uses different vendor-specific mechanisms.