Specifications

D
evice Driver Programming
14-6
By default, if the parameter has already been tuned previously, you are asked to confirm
the change with the message
Tunable Parameter parm is currently set to old_value in
/etc/conf/cf.d/stune
Is it OK to change it to value? (y/n)
If you answer y, the change is made. Otherwise, the tunable parameter is not changed, and
the following message is displayed
parm left at old_value.
However, if you use the -f (force) option, the change is always made and no messages are
reported.
If you use the -m (minimum) option, and the current value is greater than the desired
value, no change is made and no messages are reported.
If you use the -c (current) option of the idtune command, the change applies to both
stune and stune.current; otherwise, only the tunable parameter in stune is
affected. stune.current contains the values currently being used by the running
kernel; stune contains the values used the next time the system is rebooted and the ker-
nel rebuilt. Since any change made to the stune.current file affects all the loadable
kernel modules configured thereafter, it is very easy to introduce inconsistencies between
the currently running kernel and the new loadable kernel modules. Therefore, you should
be extremely careful when using the -c option.
If you are modifying system tunable parameters as part of a device driver or application
add-on package, you might want to change parameter values without prompting the user
for confirmation. Your postinstall script could override the existing value using the
-f or -m options. However, you must be careful not to invalidate a tunable parameter
modified earlier by the user or another add-on package.
Any attempt to set a parameter to a value outside the valid minimum/maximum (as given
in the Mtune file) range is reported as an error, even when using the -f or -m options.
The UNIX system kernel must be rebuilt (using idbuild) and the system rebooted for
any changes to tunable parameter values to take effect.
The Driver Software Package (DSP) 14
A Driver Software Package (DSP) is a set of files which define and describe an installable
module, such as a device driver, to the idtools. It consists of a driver object module, instal-
lation and removal scripts, and device-specific system configuration, initialization, and
shutdown files. (Some of these files are optional and are not included in every DSP.)
DSPs are usually installed as part of a software package (see System Administration Vol-
ume 1 for more information). A software package can contain more than one DSP.
The software package is usually on a tape. To install the package, the user inserts the
media in the drive and runs the pkgadd(1) command. This executes a script file in the
software package, which performs all the operations needed to copy all the object and con-