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CHAPTER 8 Kernel Configuration

8.3 IRIX 5.X

The autoconfiguration script /etc/init.d/autoconfig is run at run-level 2, S23autoconfig, during the boot process. If new boards or devices are found, or if changes have been made to the object files or system tuning files in /var/sysgen/mtune/*, /var/sysgen/master.d/*, or /var/sysgen/system/* the program will check the /var/config/autoconfig.options file to see if it should automatically generate a new kernel. The default "-T" option indicates this. Otherwise it will prompt to generate a new kernel. So you should rarely, if ever, need to generate a new kernel by hand.

autoconfig uses the lboot command to actually generate the new kernel and reads the /var/sysgen/stune file for the settings of any tunable parameters different from the defaults. This creates a new kernel and saves it as /unix.install. When doing this by hand you should then copy the old kernel, /unix, to a new name, e.g. /unix.save and reboot the system with "reboot".

The /usr/sbin/systune program can be used to examine or change kernel tunable parameters; in the latter case it will add entries to /var/sysgen/stune.

A few of the tunable parameters listed by systune are, e.g. for NFS parameters:

snfs (statically changeable)

svc_maxdupreqs = 136 (0x88)

nfs_portmon = 0 (0x0)

You can execute systune in interactive mode to examine and set parameters, e.g. to report and then raise the value for the number of system processes, nproc:

# systune -i

systune-> nproc

nproc = 300 (0x12c)

systune-> nproc 500

nproc = 300 (0x12c)

Do you really want to change nproc to 500 (0x1f4)? (y/n) y

In order for the change in parameter nproc to become effective,

reboot the system

systune-> quit

This creates the new kernel /unix.install. The parameter change will take effect the next time you reboot the system. When this file exists /etc/init.d/autoconfig reconfigures the kernel as part of the boot process.

Should you need to recover from an unbootable kernel following an unsuccessful kernel regeneration, interrupt the boot process and go to "System Maintenance Menu". There select "Command Monitor". At the ">> " prompt boot from the old kernel, e.g.:

>> boot unix.save

Unix System Administration - 8 AUG 1996
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