Storage Architecture
The legacy xv6-derived filesystem is the boot filesystem. A validated UFS2 image can be used as the root or data volume; writable operations remain limited and are not crash-safe.
| Volume | Format | Purpose |
|---|---|---|
| EFI System Partition | FAT32 | UEFI firmware compatibility only |
| System A / System B | Signed immutable images | Operating-system update and rollback slots |
| FNU Data | UFS2/FFS | Service data, durable state, audit data, and logs |
| Recovery | Immutable image | Local recovery and diagnostics |
Current implementation
FAT32 is not a root, service-state, log, or data filesystem. The UFS2 adapter validates the superblock and directory records, bounds-checks offsets, and exposes a valid optional data image at /data. The writer supports files, empty directories, direct writes, hard links and removal; symlinks and crash recovery are unavailable.