rootfs-handoff: Milestone D - adapt /sbin/init and fstab for post-handoff

- Updated /etc/fstab with documentation for post-handoff configuration
- Documented that root filesystem is already mounted by kernel on /newroot
- Documented that early /init performs pivot_root to make /newroot the new root
- Documented that virtual filesystems are moved by early /init
- Documented that /sbin/init runs after handoff and skips already-mounted filesystems
- /sbin/init already has is_mounted() check to avoid duplicate mounts
- No code changes needed in /sbin/init - already compatible with handoff

Test Results:
- Smoke test: 131/131 PASS
- Battery test: 157/157 PASS
- Analyzer: PASS
- Zero regressions

diff --git a/rootfs/etc/fstab b/rootfs/etc/fstab
index 972d0747a45b347229f1853f24ca1b230afe6ebe..1be12bc76cc7478a5e8eeae79322fe98e2e1fa51 100644 (file)
--- a/rootfs/etc/fstab
+++ b/rootfs/etc/fstab
@@ -1,4 +1,11 @@
 # /etc/fstab — AdrOS filesystem table
 # <device>      <mountpoint>  <fstype>     <options>
-# Disk-based filesystems (fat, ext2) are auto-mounted by /sbin/init
-# or the kernel when a root= device is specified.
+#
+# POST-HANDOFF CONFIGURATION (Milestone D):
+# - Root filesystem is already mounted by kernel on /newroot
+# - Early /init performs pivot_root to make /newroot the new root
+# - Virtual filesystems (/dev, /proc, /tmp) are moved by early /init
+# - /sbin/init runs after handoff and skips already-mounted filesystems
+#
+# Additional disk filesystems can be added here if needed:
+# Example: /dev/hdb1 /mnt/data ext2 defaults