Installation guide

5.1 System Configuration at Installation Time
When you install Tru64 UNIX, the installation program initially copies a
kernel image to the root partition of your system disk. This kernel image,
known as the generic kernel, supports all processors and hardware options
that are available for use with the current version of the operating system.
In this way, the installation program ensures that you can boot your
system regardless of its configuration.
Towards the end of the installation, after all the subsets you selected have
been written to disk and verified, the installation program calls the
/usr/sbin/doconfig program. As part of its processing, the
/usr/sbin/doconfig program calls another program, known as the
sizer program. The sizer program determines what hardware and
software options are installed on your system and builds a target
configuration file specific to your system. (The configuration file is the
system file that controls what hardware and software support is linked into
the kernel.) The /usr/sbin/doconfig program then builds your target
kernel from this target configuration file.
Unlike the generic kernel copied to the system at installation time, the
target kernel is tailored to your system. Only the hardware and software
options available on your system are compiled into the target kernel. As a
result, the target kernel is much smaller than the generic kernel.
When the installation is complete, the target kernel resides either in the
root partition of your system disk or in memory, depending upon how your
system was built. (See Section 5.4 for information about the different ways
in which your kernel can be built.) If the appropriate console boot variables
are set, your system always boots the target kernel automatically. (For
information about setting console boot variables, see Chapter 3.)
5.2 Deciding When and How to Reconfigure Your Kernel
After your target kernel is built and started by the installation procedure,
you can use it without modifications, unless one of the following occurs:
• You decide to add new subsystems to the kernel, for example by
installing a new device.
• You decide to remove subsystems from the kernel, for example by
removing a device.
• The performance of your system is poor, so you decide to tune values in
the kernel. These values are called subsystem attributes if they are
dynamically configurable or system parameters if they are statically
configurable.
5–2 Configuring the Kernel