Linux kerneld mini-HOWTOHenrikStornerkerneld-howto@linuxdoc.orgv2.022 May 2000 conversion from HTML to DocBook SGML.
2000Linux Documentation
ProjectCopyrightThis document is Copyright by Henrik Storner, 1996, 1997.Unless otherwise stated, Linux HOWTO documents are
copyrighted by their respective authors. Linux HOWTO documents
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to be notified of any plans to redistribute the HOWTOs. If you have questions, please contact the Linux HOWTO
coordinator, at linux-howto@sunsite.unc.edu via email.About the kerneld mini-HOWTOThis document explains how to install and use the automatic
kernel module loader kerneld. The latest released
version of this document can be found at the Linux Documentation
ProjectCreditsThis document is based on an original HTML version 1.7
dated July 19, 1997 by Henrik Storner
storner@osiris.ping.dk and was revised and
translated to DocBook DTD by Gary Lawrence Murphy
garym@teledyn.com May 20, 2000.The following people have contributed to this
mini-HOWTO at some point:Bjorn Ekwall bj0rn@blox.seBen Galliart bgallia@luc.eduCedric Tefft cedric@earthling.netBrian Miller bmiller@netspace.net.auJames C. Tsiao
jtsiao@madoka.jpl.nasa.govIf you find errors in this document, please send email to
kerneld-howto@linuxdoc.org. Your comments,
encouragement and suggestions are welcome and appreciated, and
help ensure this guide remains current and accurate.What is kerneld?The kerneld feature was introduced during the 1.3
development kernels by Bjorn Ekwall. It allows kernel modules
such as device drivers, network drivers and filesystems to be
loaded automatically when they are needed, rather than having to
do it manually with modprobe or
insmod. And for the more amusing aspects, although these are not
(yet ?) integrated with the standard kernel: It can be setup to run a user-program instead
of the default screen blanker, thus letting you use any
program as a screen-saver. Similar to the screen-blanker support, you can
also change the standard console beep into something
completely different. kerneld consists of two components: Support in the Linux kernel for sending
requests to a daemon requesting a module for a certain
task. A user-space daemon that can figure out what
modules must be loaded to fulfill the request from the
kernel. Both components must be working for the kerneld support to
function; it is not enough that only one or the other has been
setup. Why do I want to use it ?There are some good reasons for using kerneld. The ones I
will mention are mine, others have other reasons. If you have to build kernels for several
systems that only differ slightly - different kind of network
card, for instance - then you can build a single kernel and
some modules, instead of having to build individual kernels
for each system. Modules are easier for developers to test.
You don't need to reboot the system to load and unload the
driver; this applies to all modules, not just kerneld-loaded
ones. It cuts down on the kernel memory usage
leaving more memory available for applications. Memory used by
the kernel is never swapped out, so if
you have 100Kb worth of unused drivers compiled into your
kernel, they are simply wasting RAM. Some of the things I use, the ftape
floppy-tape driver, for instance, or iBCS, are only available
as modules, but I don't want to bother with loading and
unloading them whenever I need them. People making Linux distributions don't have
to build 284 different boot images: Each user loads the
drivers he needs for just his hardware. Most modern Linux
distributions will detect your hardware and will only load
those modules actually required.Of course, there are also reasons why you may not want to
use it. If you prefer to have just one kernel image file with
all of your drivers built in, you are reading the wrong
document.Where can I pick up the necessary pieces
?The support in the Linux kernel was introduced with Linux
1.3.57. If you have an earlier kernel version, you will need to
upgrade if you want the kerneld support. The current Linux
kernel sources can be found at most Linux FTP archive sites
including:Kernel.Org
ArchiveMetalab Linux
ArchiveTSX-11
at MITThe user-space daemon is included with the
modules package. These are normally
available from the same place as the kernel sources
If you want to try module-loading with the latest
development kernels, you should use the
newer modutils package and not the
modules. Always check the
Documentation/Changes file in the kernel
sources for the minimum required version number for your kernel
image. Also see about the problems with modules
and 2.1 kernels.How do I set it up?First get the necessary parts: A suitable kernel and the
latest modules package. Then you
should install the module utilities as per the instructions
included in the package. Pretty simple: Just unpack the sources
and run make install. This compiles and
installs the following programs in /sbin:
genksysm, insmod,
lsmod, modprobe,
depmod and kerneld. I
recommend you add some lines to your startup-scripts to do some
necessary setup whenever you boot Linux. Add the following lines
to your /etc/rc.d/rc.S file (if you are
running Slackware), or to
/etc/rc.d/rc.sysinit if you are running
SysVinit, i.e. Debian, Corel, RedHat, Mandrake or Caldera:
# Start kerneld - this should happen very early in the
# boot process, certainly BEFORE you run fsck on filesystems
# that might need to have disk drivers autoloaded
if [ -x /sbin/kerneld ]
then
/sbin/kerneld
fi
# Your standard fsck commands go here
# And you mount command to mount the root fs read-write
# Update kernel-module dependencies file
# Your root-fs MUST be mounted read-write by now
if [ -x /sbin/depmod ]
then
/sbin/depmod -a
fiThese commands may already be installed in your SysV init
scripts. The first part starts kerneld itself. The second calls
depmod -a at startup to build a list of all
available modules and analyzes their inter-dependencies. The
depmod map then tells kerneld if one module needs to have
another loaded before it will itself load. Recent versions of kerneld have an option to link with the
GNU gdbm library, libgdbm. If you
enable this when building the module utilities,
kerneld will not start if libgdbm is not
available which may well be the case if you have
/usr on a separate partition and start
kerneld before /usr is mounted. The
recommended solution is to move
/usr/lib/libgdbm to
/lib, or to link kerneld
statically.Next, unpack the kernel sources, configure and build a
kernel to your liking. If you have never done this before, you
should definitely read the README file at the top level of the
Linux sources. When you run make xconfig
to configure the kernel, you should pay attention to some
questions that appear early on: Enable loadable module support (CONFIG_MODULES) [Y/n/?] YYou need to select the loadable module support, or there
will be no modules for kerneld to load! Just say Yes. Kernel daemon support (CONFIG_KERNELD) [Y/n/?] YThis, of course, is also necessary. Then, a lot of the
things in the kernel can be built as modules - you will see
questions like Normal floppy disk support (CONFIG_BLK_DEV_FD) [M/n/y/?] where you can answer with an M for
Module. Generally, only the drivers necessary for
you to boot up your system should be built into the kernel; the rest
can be built as modules. Essential driversEssential drivers
required to boot your system must be compiled into the core
kernel and cannot be loaded as modules. Typically this will
include the hard-disk driver and the driver for the root
filesystem. If you have a dual-boot machine and rely on files
found in the foreign partition, you must also compile support
for that filesystem into the core kernel.When you have gone through the make
config, compile and install the new
kernel and the modules with make dep clean bzlilo
modules modules_install.Phew. Compiling a Kernel ImageThe
make zImage command will stop short of
installing a kernel and will leave the new kernel image in the
file arch/i386/boot/zImage. To use this
image, you will
need to copy it to where you keep your boot-image and install it
manually with LILO. For more information about configuring, building and
installing your own kernel, check out the Kernel-HOWTO posted
regularly to comp.os.linux.answers, and
available from the Linux
Documentation Project and its mirrors.Trying out kerneldNow reboot with the new kernel. When the system comes back
up, you can run ps ax, and you should see a
line for kerneld: PID TTY STAT TIME COMMAND
59 ? S 0:01 /sbin/kerneldOne of the nice things with kerneld is that once you have
the kernel and the daemon installed, very little setup is
needed. For a start, try using one of the drivers that you built
as a module; it is more likely than not that it will work
without further configuration. If I build the floppy driver as a
module, I could put a DOS floppy in the drive and type osiris:~ $ mdir a:
Volume in drive A has no label
Volume Serial Number is 2E2B-1102
Directory for A:/
binuti~1 gz 1942 02-14-1996 11:35a binutils-2.6.0.6-2.6.0.7.diff.gz
libc-5~1 gz 24747 02-14-1996 11:35a libc-5.3.4-5.3.5.diff.gz
2 file(s) 26689 bytesThe floppy driver works! It gets loaded automatically
by kerneld when I try to use the floppy disk. To see that the floppy module is indeed loaded, you can
run /sbin/lsmod to list all currently
loaded modules: osiris:~ $ /sbin/lsmod
Module: #pages: Used by:
floppy 11 0 (autoclean)The (autoclean) means that the module will
automatically be removed by kerneld when it has not been used
for more than one minute. So the 11 pages of memory (= 44kB,
one page is 4 kB) will only be used while I access the floppy
drive - if I don't use the floppy for more than a minute, they
are freed. Quite nice, if you are short of memory for your
applications! How does kerneld know what module
to load?Although kerneld comes with builtin knowledge about the
most common types of modules, there are situations where kerneld
will not know how to handle a request from the kernel. This is
the case with things like CD-ROM drivers or network drivers,
where there are more than one possible module that can be
loaded. The requests that the kerneld daemon gets from the kernel
is for one of the following items: a block-device driver a character-device driver a binary format a tty line discipline a filesystem a network device a network service (e.g. rarp) a network protocol (e.g. IPX)
The kerneld determines what module should be loaded by
scanning the configuration file
/etc/conf.modulesSome
distributions call this file
modules.conf. There are
two kinds of entries in this file: Paths where the module-files
are located, and aliases assigning the module to be loaded for a
given service. If you don't have this file already, you could
create it by running
/sbin/modprobe -c | grep -v '^path' /etc/conf.modulesIf you want to add yet another path directive to the
default paths, you must include all the default paths
as well, since a path directive in
/etc/conf.modules will
replaceall the ones that modprobe knows by
default! Normally you don't want to add any paths by your own,
since the built-in set should take care of all normal setups
(and then some...), I promise! On the other hand, if you just want to add an alias or an
option directive, your new entries in
/etc/conf.modules will be
added to the ones that modprobe already
knows. If you should redefine an alias or
an option, your new entries in
/etc/conf.modules will override the
built-in ones.Block devicesIf you run /sbin/modprobe -c, you
will get a listing of the modules that kerneld knows about, and
what requests they correspond to. For instance, the request that
ends up loading the floppy driver is for the block-device that
has major number 2: osiris:~ $ /sbin/modprobe -c | grep floppy
alias block-major-2 floppyWhy block-major-2 ? Because the
floppy devices /dev/fd* use major device 2
and are block devices:
osiris:~ $ ls -l /dev/fd0 /dev/fd1
brw-rw-rw- 1 root root 2, 0 Mar 3 1995 /dev/fd0
brw-r--r-- 1 root root 2, 1 Mar 3 1995 /dev/fd1Character devicesCharacter devices are dealt with in a similar
way. E.g. the ftape floppy tape driver sits on major-device
27: osiris:~ $ ls -lL /dev/ftape
crw-rw---- 1 root disk 27, 0 Jul 18 1994 /dev/ftapeHowever, kerneld does not by default know about the
ftape driver - it is not listed in the output from
/sbin/modprobe -c. So to setup kerneld to
load the ftape driver, I must add a line to the kerneld
configuration file, /etc/conf.modules:
alias char-major-27 ftapeNetwork devicesYou can also use the device name instead of the
char-major-xxx or
block-major-yyy setup. This is especially
useful for network drivers. For example, a driver for an
ne2000 netcard acting as eth0 would be
loaded with alias eth0 neIf you need to pass some options to the driver, for
example to tell the module about what IRQ the netcard is
using, you must add an options line: options ne irq=5This will cause kerneld to load the NE2000 driver with
the command /sbin/modprobe ne irq=5Of course, the actual options available are specific to
the module you are loading. Binary formatsBinary formats are handled in a similar way. Whenever
you try to run a program that the kernel does not know how to
load, kerneld gets a request for
binfmt-xxx, where
xxx is a number determined from the first
few bytes of the executable. So, the kerneld configuration to
support loading the binfmt_aout module for ZMAGIC (a.out)
executables is
alias binfmt-267 binfmt_aoutSince the magic number for ZMAGIC files is 267, if you
check /etc/magic, you will see the number
0413; keep in mind that /etc/magic uses
octal numbers where kerneld uses decimal, and octal 413 =
decimal 267. There are actually three slightly different
variants of a.out executables (NMAGIC, QMAGIC and ZMAGIC), so
for full support of the binfmt_aout module we need
alias binfmt-264 binfmt_aout # pure executable (NMAGIC)
alias binfmt-267 binfmt_aout # demand-paged executable (ZMAGIC)
alias binfmt-204 binfmt_aout # demand-paged executable (QMAGIC)a.out, Java and iBCS binary formats are recognized
automatically by kerneld, without any configuration. Line disciplines (slip, cslip and ppp)Line disciplines are requested with
tty-ldisc-x, with
x
being usually 1 (for SLIP) or 3 (for PPP). Both of these are
known by kerneld automatically. Speaking of ppp, if you want kerneld to load the
bsd_comp data compression module for ppp, then you must add
the following two lines to your
/etc/conf.modules: alias tty-ldisc-3 bsd_comp
alias ppp0 bsd_compNetwork protocol families (IPX,
AppleTalk, AX.25)Some network protocols can be loaded as modules as
well. The kernel asks kerneld for a protocol family (e.g. IPX)
with a request for
net-pf-X where
X is a number indicating what family is
wanted. E.g. net-pf-3 is AX.25,
net-pf-4 is IPX and
net-pf-5 is AppleTalk; These numbers are
determined by the AF_AX25, AF_IPX etc. definitions in the
linux source file include/linux/socket.h.
So to autoload the IPX module, you would need an entry like
this in /etc/conf.modules: alias net-pf-4 ipxSee for information
about how you can avoid some annoying boot-time messages
related to undefined protocol families. File systemskerneld requests for filesystems are simply the name of
the filesystem type. A common use of this would be to load the
isofs module for CD-ROM filesystems, i.e. filesystems of type
iso9660: alias iso9660 isofsDevices requiring special
configurationSome devices require a bit of extra configuration beyond the
normal aliasing of a device to a module. Character devices on major number 10: The miscellaneous
devicesSCSI devices
Devices that require
special initializationchar-major-10 : Mice, watchdogs and randomnessHardware devices are usually identified through their
major device numbers, e.g. ftape is
char-major-27. However, if you look through
the entries in /dev for char major 10,
you will see that this is a bunch of very different devices,
including Mice of various sorts (bus mice, PS/2
mice)Watchdog devices The kernel random
device APM (Advanced Power Management) interface
These devices are controlled by several different
modules, not a single one, and therefore the kerneld
configuration for these misc. devices
use the major number and the minor
number: alias char-major-10-1 psaux # For PS/2 mouse
alias char-major-10-130 wdt # For WDT watchdogYou need a kernel version 1.3.82 or later to use this;
earlier versions do not pass the minor number to kerneld,
making it impossible for kerneld to figure out which of the
misc. device modules to load. Loading SCSI drivers: The
<literal moreinfo="none">scsi_hostadapter</literal> entryDrivers for SCSI devices consist of a driver for the
SCSI host adapter (e.g. an Adaptec 1542), and a driver for the
type of SCSI device you use, e.g. a hard disk, a CD-ROM or a
tape-drive. All of these can be loaded as modules. However,
when you want to access e.g. the CD-ROM drive that is
connected to the Adaptec card, the kernel and kerneld only
knows that it needs to load the sr_mod
module in order to support SCSI CD-ROM's; it does not know
what SCSI controller the CD-ROM is connected to, and hence
does not know what module to load to support the SCSI
controller. To resolve this, you can add an entry for the SCSI
driver module to your /etc/conf.modules
that tells kerneld which of the many possible SCSI controller
modules it should load: alias scd0 sr_mod # sr_mod for SCSI CD-ROM's ...
alias scsi_hostadapter aha1542 # ... need the Adaptec driverThis only works with kernel version 1.3.82 or later. This works if you have only one SCSI controller. If you
have more than one, things become a little more
difficult.In general, you cannot have kerneld load a driver for a
SCSI host adapter, if a driver for another host adapter is
already installed. You must either build both drivers into
your kernel (not as modules), or load the modules
manually.There is a way that you can
have kerneld load multiple SCSI drivers. James Tsiao came up
with this idea:
You can easily have kerneld load the second scsi
driver by setting up the dependency in your modules.dep by
hand. You just need an entry like: /lib/modules/2.0.30/scsi/st.o: /lib/modules/2.0.30/scsi/aha1542.oTo have kerneld load the
aha1542.o before it loads
st.o. My machine at home is set up
almost exactly like the setup above, and it works fine for
all my secondary scsi devices, including tape, cd-rom, and
generic scsi devices. The drawback is that
depmod -a can't autodetect these
dependencies, so the user needs to add them by hand, and
not run depmod -a on boot up. But once
it is set up, kerneld will autoload the
aha1542.o just
fine.
You should be aware, that this technique only works if
you have different kinds of SCSI devices on the two
controllers, for example, hard disks on one controller, and
cd-rom drives, tapes or generic SCSI devices on another.When loading a module isn't enough: The
<literal moreinfo="none">post-install</literal> entrySometimes, just loading the module is not enough to get
things working. For instance, if you have your sound card
compiled as a module, it is often convenient to set a certain
volume level. Only problem is, the setting vanishes the next
time the module is loaded. Here is a neat trick from Ben
Galliart (bgallia@luc.edu):
The final solution required installing the setmix package and then
adding the following line to my
/etc/conf.modules: post-install sound /usr/local/bin/setmix -f /etc/volume.conf
What this does is that after the sound module is loaded,
kerneld runs the command indicated by the
post-install sound entry. So the sound
module gets configured with the command
/usr/local/bin/setmix -f
/etc/volume.conf.This may be useful for other modules as well, for
example the lp module can be configured
with the tunelp program by adding
post-install lp tunelp optionsFor kerneld to recognize these options, you will need a
version of kerneld that is 1.3.69f or later.An earlier version of this mini-HOWTO mentioned a
pre-remove option, that might be used to run a command just
before kerneld removed a module. However, this has never
worked and its use is therefore discouraged - most likely,
this option will disappear in a future kerneld release. The
whole issue of module settings is undergoing some change at
the moment, and may look different on your system by the
time you read this. Spying on kerneldIf you have tried everything, and just cannot figure out
what the kernel is asking kerneld to do, there is a way of
seeing the requests that kerneld receives, and hence to figure
out what should go into /etc/conf.modules:
The kdstat utility. This nifty little program comes with the modules-package,
but it is not compiled or installed by default. To build it, go
to the directory where you have the kerneld sources and type
make kdstat. Then, to make kerneld display
information about what it is doing, run kdstat debug
and kerneld will start spewing messages on the
console about what it is doing. If you then try and run the
command that you want to use, you will see the kerneld requests;
these can be put into /etc/conf.modules and
aliased to the module needed to get the job done. To turn off the debugging, run /sbin/kdstat
nodebug. Special kerneld usesI knew you would ask about how to setup the screen-saver
module!The kerneld/GOODIES directory in
modules package has a couple of kernel patches for screen-saver
and console-beep support in kerneld; these are not yet part of
the official kernel, so you will need to install the
kernel-patches and rebuild the kernel. To install a patch, you use the patch command: cd /usr/src/linux
patch -s -p1 /usr/src/modules-*/kerneld/GOODIES/blanker_patchThen rebuild and install the new kernel. When the screen-saver triggers, kerneld will run the
command /sbin/screenblanker; this file may
be anything you like, for example, a shell script that runs your
favorite screen-saver. When the kernel wants to unblank the screen, it sends a
SIGQUIT signal to the process running
/sbin/screenblanker. Your shell script or
screen-saver should trap this, and terminate. Remember to restore
the screen to the original text mode! Common problems and things that make you wonderWhy do I get Cannot locate module for
net-pf-X messages when I
run /sbin/ifconfig?Around kernel version 1.3.80, the networking code
was changed to allow loading protocol families (e.g. IPX,
AX.25 and AppleTalk) as modules. This caused the addition
of a new kerneld request:
net-pf-X, where
X is a number identifying the protocol
(see
/usr/src/linux/include/linux/socket.h
for the meaning of the various numbers). Unfortunately,
ifconfig accidentally triggers these
messages, so a lot of people get a couple of messages
logged when the system boots and it runs
ifconfig to setup the loopback
device. The messages are harmless, and you can disable
them by adding the lines alias net-pf-3 off # Forget AX.25
alias net-pf-4 off # Forget IPX
alias net-pf-5 off # Forget AppleTalkto /etc/conf.modules. Of
course, if you do use IPX as a module, you should not add
a line to disable IPX. After starting kerneld, my system slows to a crawl
when I activate my ppp-connectionThere have been a couple of reports of this. It
seems to be an unfortunate interaction between kerneld and
the tkPPP script that is used
on some systems to setup and monitor the PPP
connection. The script apparently runs loops while running
ifconfig. This triggers kerneld, to
look for the
net-pf-X modules
(see above), keeping the system load high and possibly
pouring lots of Cannot locate module for
net-pf-X messages
into the system log. There is no known workaround, other
than not use tkPPP, or change
it to use some other way of monitoring the
connection.kerneld does not load my SCSI driver!Add an entry for the SCSI hostadapter to your
/etc/conf.modules. See the
description of the scsi_hostadapter
entry above.modprobe complains about
gcc2_compiled being
undefinedThis is a bug in the module utilities, that show up
only with binutils 2.6.0.9 and later, and it is also
documented in the release note for the binutils. So read
that, or fetch an upgrade to the module-utilities that fix
this bug. My sound driver keeps forgetting its settings for
volume etcThe settings for a module are stored inside the
module itself when it is loaded. So when kerneld
auto-unloads a module, any settings you have made are
forgotten, and the next time the module loads it reverts
to the default settings. You can tell kerneld to configure a module by
running a program after the module has been
auto-loaded. See on the
post-install entry. DOSEMU needs some modules; how can I get kerneld to
load those ?You cannot. None of the dosemu versions, official or
development versions, support loading the dosemu modules
through kerneld. However, if you are running kernel 2.0.26
or later, you do not need the special dosemu modules any
longer; just upgrade dosemu to 0.66.1 or higher.Why do I get Ouch, kerneld timed out,
message failed messages ?When the kernel sends a request off to to kerneld,
it expects to receive an acknowledgment back within one
second. If kerneld does not send this acknowledgment,
this message is logged. The request is retransmitted, and
should get through eventually. This usually happens on systems with a very high
load. Since kerneld is a user-mode process, it is
scheduled just like any other process on the system. At
times of high load, it may not get to run in time to send
back the acknowledgment before the kernel times
out. If this happens even when the load is light, try
restarting kerneld. Kill the kerneld process, and start
it again with the command /usr/sbin/kerneld. If the problem persists,
you should mail a bug report to
linux-kernel@vger.rutgers.edu, but
please make sure that your versions
of the kernel, kerneld and the module utilities are
up-to-date before posting about the problem. Check the
requirements in
linux/Documentation/ChangesMount doesn't wait for kerneld to load the
filesystem moduleThere has been a number of reports that the mount(8)
command does not wait for kerneld to load the filesystem
module. lsmod does show that kerneld
loads the module, and if you repeat the mount command
immediately it will succeed. This appears to be a bug in
the module-utilities version 1.3.69f that affects some
Debian users. It can be fixed by getting a later version
of the module-utilities. kerneld fails to load the ncpfs
moduleYou need to compile the ncpfs utilities with
-DHAVE_KERNELD. See the
ncpfsMakefile. kerneld fails to load the smbfs
moduleYou are using an older version of the
smbmount utilities. Get the
latest version (0.10 or later) from the
SMBFS archive one TSX-11I built everything as modules, and now my system
cannot boot or kerneld fails to load the root filesystem
module!You cannot modularize
everything: The kernel must have
enough drivers built in for it to be able to mount your
root filesystem, and run the necessary programs to start
kerneldActually, this is not true. Late
1.3.x and all 2.x kernels support the use of an initial
ram-disk that is loaded by LILO or LOADLIN; it is possible
to load modules from this disk very early in the boot
process. How to do it is described in the
linux/Documentation/initrd.txt file
that comes with the kernel source-files. . You cannot modularize the driver for the hard disk
where your root filesystem lives the root filesystem driver itself
the binary format loader for init,
kerneld and other programs kerneld will not load at boot time; it complains
about libgdbmNewer versions of kerneld need the GNU dbm library,
libgdbm.so, to run. Most
installations have this file in
/usr/lib, but you are probably
starting kerneld before the /usr
filesystem is mounted. One symptom of this is that kerneld
will not start during boot-up (from your rc-scripts), but
runs fine if you start it by hand after that system is
up. The solution is to either move the kerneld startup to
after your /usr is mounted, or move
the gdbm library to your root filesystem, e.g. to
/lib.I get Cannot load module xxx but
I just reconfigured my kernel without
xxx support!The Slackware installation (possibly others) builds
a default /etc/rc.d/rc.modules which
does an explicit modprobe on a variety of modules. Exactly
which modules get modprobed depends on the original
kernel's configuration. You have probably reconfigured
your kernel to exclude one or more of the modules that is
getting modprobed in rc.modules, thus, the error
message(s). Update your rc.modules by commenting out any
modules you no longer use, or remove the
rc.modules entirely and let kerneld
load the modules when they are needed.I rebuilt my kernel and modules, and still get
messages about unresolved symbols when
bootingYou probably reconfigured/rebuilt your kernel and
excluded some modules. You've got some old modules that
you no longer use hanging around in the
/lib/modules directory. The easiest
fix is to delete your
/lib/modules/x.y.z
directory and do a make modules_install
from the kernel source directory again. Note that this
problem only occurs when reconfiguring your kernel without
changing versions. If you see this error when moving to a
newer kernel version you've got some other problem.I installed Linux 2.1/2.3 and now I cannot
load any modules!Odd numbered Linux are development kernels. As such,
it should be expected that things break from time to
time. One of the things that has changed significantly is
the way modules are handled, and where the kernel and
modules are loaded into memory.In brief, if you want to use modules with a
development kernel, you mustread the
Documentation/Changes file and see
what packages need upgrading on your systemuse the latest modutils package,
available from AlphaBits on
Red Hat or the mirror site at TSX-11I recommend using at least kernel 2.1.29, if you
want to use modules with a 2.1 kernel.What about dial-on-demand networking?kerneld originally had some support for establishing
dial-up network connections on demand; trying to send
packets to a network without being connected would cause
kerneld to run the
/sbin/request_route script to setup a
PPP or SLIP connection.This turned out to be a bad idea. Alan Cox of Linux
networking fame wrote on the linux-kernel mailing list
The request-route stuff is obsolete, broken and
not required [...] Its also removed from 2.1.x
trees.
Instead of using the request-route script and
kerneld, I highly recommend Eric Schenk's diald
package to manage your demand dialing.