Placing symmon in the Volume Header

Placing symmon in the Volume Header

The symmon standalone debugger resides in the volume header of a disk--not in a normal IRIX filesystem. The volume header is disk partition 0. It always contains a label record (sgilabel), and the standalone shell sash that manages the bootstrap operation. On some systems it may also contain the ide program, a PROM-level diagnostic program. If symmon is to be available, it, too, must be placed in the volume header.

Normally you acquire symmon by installing the debugging kernel feature (eoe.sw.kdebug) in the IRIX Developer Option software distribution. You can verify that this feature has been installed by executing the command

versions eoe.sw.kdebug

The response should confirm the presence of this component (it does not show symmon by name). When you install the kernel debug feature, the symmon program file is copied to the volume header of the current boot disk automatically.

You can verify the presence of symmon in the volume header through the use of dvhtool (described in the dvhtool(1) reference page). The results should be similar to the display in Example 11-1. The response to the "l" (list) command shows that the volume header of this disk contains sgilabel, ide, sash, and symmon.

Example 11-1 : Verifying Presence of symmon

# dvhtool  
Volume? (/dev/rvh) /dev/rvh
Command? (read, vd, pt, dp, write, bootfile, or quit): vd
(d FILE, a UNIX_FILE FILE, c UNIX_FILE FILE, g FILE UNIX_FILE or l)?
        l
Current contents:
        File name        Length     Block #
        sgilabel            512           2
        ide              281600         278
        sash             281600         828
        symmon           248320        1378
(d FILE, a UNIX_FILE FILE, c UNIX_FILE FILE, g FILE UNIX_FILE or l)?

Command? (read, vd, pt, dp, write, bootfile, or quit): quit
#

In the event you need to install symmon in the volume header of a disk without using the software manager, you can copy the standalone program to the volume header using dvhtool. However, you first need to get a copy of the program in the form of a UNIX file.

Starting from a volume that currently has a copy of symmon (verified as in Example 11-1), use dvhtool to extract a copy of symmon into a convenient spot.

dvhtool -v g symmon /var/tmp/symmon.IPxx

There is a unique version of symmon for each CPU module, so it is a good idea to qualify the filename with the CPU module type. Once the program is available as a normal file, you can use dvhtool to install it in the volume header of some other disk.

In the event there is not enough room in partition 0 (the volume header) of the target disk, it is safe to use dvhtool to delete the ide program from the volume header. The ide application can be booted manually from a CDROM if it is ever required.