Writing Device Drivers

Recovering the Device Directory

Damage to the /devices and /dev directories can occur if the driver crashes during attach(9E). If either directory is damaged, you can rebuild the directory by booting the system and running fsck(1M) to repair the damaged root file system. The root file system can then be mounted. Recreate the /devices and /dev directories by running devfsadm(1M) and specifying the /devices directory on the mounted disk.

The following example shows how to repair a damaged root file system on a SPARC system. In this example, the damaged disk is /dev/dsk/c0t3d0s0, and an alternate boot disk is /dev/dsk/c0t1d0s0.

Example 22–6 Recovering a Damaged Device Directory

ok boot disk1
Rebooting with command: boot kernel.test/sparcv9/unix
Boot device: /sbus@1f,0/espdma@e,8400000/esp@e,8800000/sd@31,0:a File and \
# fsck /dev/dsk/c0t3d0s0** /dev/dsk/c0t3d0s0
** Last Mounted on /
** Phase 1 - Check Blocks and Sizes
** Phase 2 - Check Pathnames
** Phase 3 - Check Connectivity
** Phase 4 - Check Reference Counts
** Phase 5 - Check Cyl groups
1478 files, 9922 used, 29261 free
     (141 frags, 3640 blocks, 0.4% fragmentation)
# mount /dev/dsk/c0t3d0s0 /mnt
# devfsadm -r /mnt

Note –

A fix to the /devices and /dev directories can allow the system to boot while other parts of the system are still corrupted. Such repairs are only a temporary fix to save information, such as system crash dumps, before reinstalling the system.