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For most systems, the default kernel configuration included
with HP-UX will be sufficient for your needs. However, in each of
the following instances you need to reconfigure the kernel: Adding or removing device
drivers The most common reason for adding or removing kernel modules
is to add or remove device drivers. See Configuring HP-UX
for Peripherals for full instructions on adding peripherals. You may also want to remove a driver from your kernel if your
system is not using any peripherals of that type. This is not required,
but can be desirable if a smaller, more efficient kernel is needed. To add or remove traditional drivers which are statically
linked to the kernel, a whole kernel configuration and system reboot
are required. See “Steps to Reconfigure the Kernel ”,
and “Steps to Perform Whole Kernel Configuration
Using HP-UX Commands” for details. However, before you remove the driver, ensure that other drivers
are not dependent on it by checking the files in the directory /usr/conf/master.d/ for a table of driver dependencies in the section DRIVER_DEPENDENCY.
The file core-hpux will have the most definitions, but other files in the
directory can contain definitions as well. If the device driver that controls the peripheral is a dynamically
loadable module (a DLKM), you may be able to add or remove the drivers
from the running kernel without needing to reboot. See the white
paper Managing and Developing Dynamically Loadable Kernel
Modules for instructions on adding or removing DLKM
modules. Modifying system parameters You may need to change one or more tunable system parameters.
For example, to accommodate a specialized application or an exceptionally
large number of users. Historically, all tunables have been static, but as of HP-UX Release 11i,
a tunable may be either static, dynamic, or automatic. A static tunable is one
whose value cannot be changed without rebooting the system. Usually
a kernel rebuild is also required. An automatic tunable is one that is constantly being
tuned by the kernel itself in response to changing system conditions.
The list of dynamic and automatic tunables is continually
growing. To determine which tunables are dynamic on your system,
use the kmtune(1M) command),
or see the Kernel Configuration portion of SAM. In SAM's Configurable Parameters screen, administrators can tell at a glance whether or
not the value of a particular tunable can be changed without a reboot. The tunable system parameters are edited using SAM or kmtune. When SAM is used to change a tunable, the administrator is
informed whether or not that change requires a reboot. If no reboot
is required, SAM makes the change to the tunable immediately. For more information on dynamic tunables, see the Dynamically
Tunable Kernel Parameters in HP-UX 11i white paper. Adding certain Hewlett-Packard or third-party
vendor software If you add certain optional add-on software, such as LAN (Local
Area Network) or NS (Network Services), you might need to reconfigure
the kernel. If kernel modules are installed with the software they
may be traditional static kernel modules or DLKMs. Traditional kernel
modules require whole kernel configuration and system reboot. DLKMs may
be dynamically configured into the running kernel and may not require
system reboot. Consult the manual that came with the software for
installation instructions. Creating a file system of a type other
than JFS Depending on how your kernel is configured, you might have
to reconfigure if you created a file system of a type other than
the default file system (JFS). See Managing Systems and Workgroups:
A Guide for HP-UX System Administrators
for
information on file system types. Adding, removing, or modifying swap,
dump, console devices or the root file system You will need to perform whole kernel configuration for adding
or removing dump devices and modifying the location of primary swap
or the system console. For information on swap space, see the section "Managing
Swap and Dump" in Chapter 3, "Configuring a System" in Managing
Systems and Workgroups: A Guide for HP-UX System Administrators. To add, remove, or modify the root file system, you will not
be able to use SAM. Instead, re-install your system or see "Creating
Root Volume Group and Root and Root and Boot Logical Volumes" in
Chapter 3, "Configuring a System" in Managing
Systems and Workgroups: A Guide for HP-UX System Administrators,
if you are using logical volumes.
| | | |  | NOTE: If you have cold-installed an HP 9000 Model T500 and
you are configuring a large number of file systems (approximately
100 or more), some default table sizes in the kernel may be too
small for your system to successfully boot. To boot your system,
reconfigure the install kernel before the first boot. Refer to the
section “Steps to Reconfigure the Kernel ” to perform
this, keeping in mind that SAM is not available at this point. The
following settings, although not necessarily optimal for the system,
will allow the kernel to be booted:Table 1-1 useradd Options Kernel Parameters | Default | Recommended Setting |
|---|
ninode | 476 | 2048 | nproc | 276 | 1024 | nfile | 790 | 2048 |
Alternatively, you can do the following: Reconfigure the kernel and change
the value of mixers to a large value, such as 200. Select an appropriate bundle of SAM-tuned parameters
by doing the following: Open the “SAM Kernel Configuration” menu item Select “Configured Parameters” Pull down the “Actions” menu Select “Apply Tuned Parameter Set”
For further details, refer to Installing HP-UX
11.0 and Updating HP-UX 10.x to 11.0. | | | | |
Steps to Reconfigure the Kernel | |
You can use SAM or HP-UX commands to reconfigure the kernel. To use SAM to reconfigure the kernel, log in as the superuser, ensure
you are logged on to the machine for which you are regenerating
the kernel, and start SAM. Select the Kernel Configuration menu item; use SAM's online help if needed.
Generally, SAM is simpler to use than the equivalent HP-UX commands. SAM will also help you determine whether a whole kernel configuration
and/or system reboot are necessary, or if a dynamic configuration
of the running kernel is all you need (for example, when adding
or removing DLKMs). Since the introduction of DLKMs, dynamic kernel configuration
of the running kernel is possible when adding or removing a DLKM.
Although HP-UX Release 11i Version 1.5 is not released with DLKM
content, certain optional add-on HP-UX software is available as
DLKM modules. If using HP-UX commands to add or remove static traditional
kernel modules, follow the instructions outlined in “Steps to Perform Whole Kernel Configuration
Using HP-UX Commands”. To add or remove DLKM kernel
modules, refer to the white paper Managing and Developing
Dynamically Loadable Kernel Modules. Steps to Perform Whole Kernel Configuration
Using HP-UX CommandsTo use HP-UX commands to reconfigure the kernel: Log in as superuser on the machine for which a new kernel
is being generated. You can log in remotely from another location
by using the /usr/bin/rlogin command. Change directory to the build environment (/stand/build). There, execute a system preparation script, system_prep. system_prep writes a system file based on your current kernel in
the current directory. (That is, it creates /stand/build/system.) The -v provides verbose explanation
as the script executes. cd /stand/build
/usr/lbin/sysadm/system_prep -v -s system |
Use the kmsystem(1M) command: /usr/sbin/kmsystem -S /stand/build/system |
to view the kernel modules that were already explicitly selected
for the next kernel build: Note that additional kernel modules may be configured because
of module dependencies or because they are required kernel modules
as indicated in their master files. Add absent kernel modules (like device drivers) using the kmsystem command. The -c Y option specifies
the module name to be configured into the system: /usr/sbin/kmsystem -S /stand/build/system -c Y driver-name |
| | | | | NOTE: Direct edits to the HP-UX system description files to
add or remove kernel modules is not a supported kernel configuration
interface, and is likely to introduce configuration errors. Instead,
use the commands kmsystem(1M) and kmtune(1M),
available since Release 11.0. | | | | |
Build the new kernel by invoking mk_kernel(1M): /usr/sbin/mk_kernel -s /stand/build/system |
This builds a new kernel ready for testing: /stand/build/vmunix_test and the associated kernel components. Perform a kernel update using kmupdate(1M) : This is a required step that will make the newly configured
kernel bootable. kmupdate also saves the currently running kernel under a new name, /stand/vmunix.prev, and schedules the update of the system to use the default
name /stand/vmunix for the newly configured kernel. | | | |  | CAUTION: Avoid copying kernel files; doing so may result in
corrupting the running kernel, or any other configured kernel on
the system. | | | | |
| | | | | NOTE: A whole kernel configuration must be
followed by a kernel update step initiated with the kmupdate(1M) command
in order to be able to successfully boot the new kernel. A configured,
bootable kernel is no longer composed of a single file. Each new
kernel configured with mk_kernel(1M) or config(1M) is
composed of several files, including the main kernel file, the loadable images
for DLKMs, a symbol table file, and a kernel-specific KRS file.
The main kernel file (for example, /stand/vmunix) carries the name of the kernel, but is not sufficient
to boot a kernel. All component files of the kernel are essential
for the kernel to boot and run properly. The kmupdate command understands the organization of these files and
prepares a directory structure accessible to the boot loader that
will allow a newly generated kernel to boot and run properly. | | | | |
Notify users that the system will be shut down.
You can use the/usr/sbin/wall command and/or the interactive capabilities of the /usr/sbin/shutdown command to broadcast a message to users before the system
goes down. For details, see wall(1M), shutdown(1M), and "Shutting
Down Systems," in Chapter 3, "Configuring a System," in Managing Systems
and Workgroups: A Guide for HP-UX System Administrators. | | | | | NOTE: You only need to do the next steps if you are changing
hardware, such as adding new peripherals. If you are only adding
or removing a kernel module, or simply changing a static kernel
parameter, reboot the system to active the new kernel with shutdown -r. | | | | |
Bring the system to a halt using the shutdown command. Turn off the power to all peripheral devices and then to
the SPU. Install the hardware or remove interface cards or
peripheral devices. Refer to the documents shipped with the products
being installed and to Configuring HP-UX for Peripherals for
specific instructions. Turn on the power to all peripheral devices. Wait
for them to become “ready”, then turn
on power to the SPU. The system will attempt to boot the new kernel.
If the New Kernel Fails to Boot | |
If the new kernel fails to boot Saving a Backup Kernel Permanently | |
System administrators and kernel developers often like to
save a trusted good kernel (for example, the default kernel, /stand/vmunix, running at the end of a clean OS installation), before
starting the process of building new kernels. Although the kmupdate(1M) command always saves the
previous /stand/vmunix kernel to the kernel name /stand/vmunix.prev, you must be aware that a subsequent use of kmupdate will again overwrite the vmunix.prev kernel. The recommended way to permanently save /stand/vmunix is to move (do not copy)/stand/vmunix to a safe name such as /stand/vmunix.bkup. Furthermore, if /stand/vmunix had been the running kernel, we recommend an immediate reboot
from the renamed location: # mv /stand/vmunix /stand/vmunix.bkup
# shutdown -r Once /stand/vmunix has been moved, there is no longer a default kernel
from which to boot, until a new kernel is configured and updated
with the kmupdate command. To boot from a non-default kernel, refer to "Booting
from an Alternate Kernel" in the chapter "Administering a
System: Booting and Shutdown," in Managing Systems
and Workgroups: A Guide for HP-UX System Administrators. | | | | | CAUTION: Although the main kernel file (for example /stand/vmunix) carries the name of the kernel, you must remember that
a kernel is no longer contained in that single file, but is composed
of several essential files, and depends on a specific directory
structure and symbolic links to be set properly for the kernel to
be able to boot. The old unsupported practice of copying the /stand/vmunix file may result in the eventual loss of the kernel component
set necessary to boot the copy. | | | | |
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