1.1. WARNING NOTICE

It is the usual industry practice to have a debug PC box, a test PC box, and a production PC box. Nobody works directly on a production box without experimenting first on debug PC and test PC. This is because the skills of a person varies and every person needs a warm-up exercise before doing the final show. A computer hardware is a very sophisticated technology like "Space Shuttle" and risks are involved as it can fail unexpectedly. Eventhough efforts are made to ensure that this document is upto-date and all commands are pre-tested, it is strongly recommended that you should practice your skills first on a trainer test PC before you do anything to "LIVE" production box. You will sharpen your skills and hone your knowledge first on a test PC running Linux and after everything works, then change the production box with extreme caution. Even if you break the test PC with dangerous commands you will learn by doing mistakes and you can afford breaking the test PC. You will be more confident working first on Test PC. Most companies purchase old PCs for using them as "Trainer Machines". Please understand that there is no warranty or guaranty on this document and you can build your own warranty by checking this document with your test PC or your home PC (low risk environments). (Write your own warranty document and hang it on wall near your computer!!)

2.1. Precautionary Preparations

Before you build kernel, it is a good idea to do a backup of the system. If you had not backed up your system recently then you can do it now. You can use commercial backup tools like BRS Backup-Recovery-Software (also in this page you can find open-source/freeware backup tools listed under 'Backup and Restore Utility'). Backup is just a suggestion and it is not mandatory to do backup before building the Linux kernel.

2.2. Minor Upgrading of Kernel

If you had already built the kernel and you want to upgrade to next patch release, then you can simply copy the existing config file and reuse it. (For example you have built kernel 2.4.19 and want to upgrade to 2.4.20).

For minor upgrades : This step may save you time, if you want to reuse the old settings. Whenever you install the kernel, generally you put the config file in /boot. Do not save the .config as .config.save because 'make mrproper' will wipe out all .config* files!! So, you can use the existing version of config file:

bash# mkdir /usr/src/kernelconfigs bash# cp /usr/src/linux/.config /usr/src/kernelconfigs/.config.save bash# cp /usr/src/linux/.config /usr/src/linux/configs/.config.save # ExtraSafe bash# cp /boot/config* /usr/src/linux/configs/ # ExtraSafe bash# cp /boot/config-2.4.18-19.8.0 /usr/src/linux/.config

Or another method is - you can copy the .config file from your old linux kernel source tree to new kernel tree.

bash# ls -l /usr/src/lin* # You can see that /usr/src/linux is a soft link bash# cd /usr/src/linux bash# cp ../linux-old-tree/.config . # Example cp ../linux-2.4.19/.config .

or one other method is - you can use "make oldconfig" which default all questions based on the contents of your existing ./.config file.

NOTE: If you do not have lot of disk space in /usr/src then you can unpack the kernel source package on any partition where you have free disk space (like /home). Because kernel compile needs lot of disk space for object files like *.o. For this reason the /usr/src/linux MUST be a soft link pointing to your source directory.

After this, look in the next section to do make and install.

2.3. New Release Changes: Documentation

If you downloaded the new kernel sources, then make sure you read the following files in /usr/src/linux/Documentation

• Changes: This file lists the minimum requirements and some notes

• kernel.txt: This file has 'Understanding the Linux Kernel'

• Read all *.txt files in /usr/src/linux/Documentation but most important ones are kernel*.txt files.

2.4. For the Impatient

1. Unpack the sources

2. cd /usr/src/linux; mkdir /usr/src/kernelconfigs ; cp /usr/src/linux/.config /usr/src/kernelconfigs/.config.save; make clean; make mrproper; make clean; cp /usr/src/kernelconfigs/.config.save .config # In case you want to reuse the config file ??

3. Optional - Copy config file : You can copy the config file from your old linux kernel source tree to new kernel tree (may save time, if you want to reuse the old settings).

4. make xconfig # Nicer, but limited; only runs in "X"

5. make dep

6. Give a unique name to your new Kernel - Edit /usr/src/linux/Makefile and change EXTRAVERSION

7. nohup make bzImage

8. 'make modules' and 'make modules_install'

9. And you can go to lunch or go to bed (have nice Linux dreams in sleep) and when you come back the system is ready! And see the log with 'less nohup.out'.

10. make install # But "NOT recommended" - use cp /usr/src/linux/arch/i386/boot/bzImage /boot/bzImage.myker

    Copy the System.map file to /boot # cp System*.map* /boot/

    Copy your kernel "configuration file" (the options you selected) Not required but will be useful later. cp .config /boot/config.KERNEL_VERSION.Name

11. Configure GRUB or LILO.

12. Reboot and check new kernel is booting

13. Create emergency boot disk - bzdisk or mkbootdisk

14. Optional - make rpm # To build rpm packages

15. Optional - make clean (If you want to free up disk space)

See details of above steps in the following sections....

2.5. Building New Kernel - Explanation of Steps

Details of the steps mentioned in the previous section:

Note: Below 'bash#' denotes the bash prompt, you should type the commands that appear after the 'bash#' prompt. Below are commands tested on Redhat Linux Kernel 2.4.7-10, but it should work for other distributions with very minor changes. It should also work for older kernel versions like 2.2, 2.0 and 1.3. It should also work for future or newer versions of kernel (with little changes - let me know).

• Note: You can have many kernel images on your system. By following the steps below you do not overwrite or damage your existing kernel. These steps are very safe and your current kernel will be intact and will not be touched.

1. Unpack the sources: Login in as 'root' throughout all these steps. Mount Redhat linux cdrom (Disc 2 of Redhat9) and install the linux kernel source rpm

   bash$ su - root bash# cd /mnt/cdrom/RedHat/RPMS bash# rpm -i kernel-headers*.rpm bash# rpm -i kernel-source*.rpm bash# rpm -i dev86*.rpm bash# rpm -i bin86*.rpm

   (The bin86*.rpm and 'as86' is required only for OLDER Linux systems like Redhat 5.x. Get Intel assembler 'as86' command from dev86*.rpm on cdrom or from bin86-mandrake , bin86-kondara ). In latest Redhat 9, the kernel-source.rpm contains the kernel-headers. Usually kernel source is on Redhat discs or in SRPMs disc. Otherwise, you can get from rpmfind.net kernel-source (look for RawHide for latest Redhat) and rpmfind.net kernel-headers . Also make sure that /usr/src/linux is soft link pointing to proper unpacked source.

   bash# cd /usr/src bash# ls -l # You should see that /usr/src/linux is soft link pointing to source lrwxrwxrwx 1 root root 19 Jan 26 11:01 linux -> linux-2.4.18-19.8.0 drwxr-xr-x 17 root root 4096 Jan 25 21:08 linux-2.4.18-14 drwxr-xr-x 17 root root 4096 Mar 26 12:50 linux-2.4.18-19.8.0 drwxr-xr-x 7 root root 4096 Jan 14 16:32 redhat

   If it is not a soft link then do rename /usr/src/linux to /usr/src/linux-2.4.yy and create a soft link.

   NOTE: If you do not have lot of disk space in /usr/src then you can unpack the kernel source package on any partition where you have free disk space (like /home). Because kernel compile needs lot of disk space for object files like *.o. For this reason the /usr/src/linux MUST be a soft link pointing to your source directory.

2. Clean : Before doing mrproper below, you may want to backup the .config file.

   bash# cd /usr/src/linux bash# mkdir /usr/src/kernelconfigs ; bash# cp /usr/src/linux/.config /usr/src/kernelconfigs/.config.save; bash# cp /usr/src/linux/.config /usr/src/linux/configs/.config.save # ExtraSafe bash# cp /boot/config* /usr/src/linux/configs/ # ExtraSafe bash# make clean bash# make mrproper # "MUST DO THIS mrproper", otherwise you will face hell lot of problems !! bash# make clean bash# cp /usr/src/kernelconfigs/.config.save .config # In case you want to reuse the config file ??

3. Optional - Copy config file : This step may save you time, if you want to reuse the old settings. Whenever you install the kernel, generally you put the config file in /boot. There are some baseline config files which are located in /usr/src/linux/configs/kernel-*.config which you can use. So, you can use the existing version of config file:

   bash# mkdir /usr/src/kernelconfigs ; bash# cp /usr/src/linux/.config /usr/src/kernelconfigs/.config.save; bash# cp /usr/src/linux/.config /usr/src/linux/configs/.config.save # ExtraSafe bash# cp /boot/config* /usr/src/linux/configs/ # ExtraSafe bash# cp /boot/config-2.4.18-19.8.0 /usr/src/linux/.config Or copy from the default vanilla config file from /usr/src/linux/configs bash# cp /usr/src/linux/configs/kernel-2.4.18-i686.config /usr/src/linux/.config Or for athlon processors bash# cp /usr/src/linux/configs/kernel-2.4.18-athlon.config /usr/src/linux/.config

   Or another method is - you can copy the .config file from your old linux kernel source tree to new kernel tree

   bash# ls -l /usr/src/lin* # You can see that /usr/src/linux is a soft link bash# cd /usr/src/linux bash# cp ../linux-old-tree/.config . # Example cp ../linux-2.4.19/.config .

   or one other method is - you can use "make oldconfig" which default all questions based on the contents of your existing ./.config file.

4. Configure:

   • Start X-windows with 'startx'. If you are not able to start X-window then see next step below.

     bash# man startx bash# startx bash# cd /usr/src/linux bash# make xconfig # Nicer, but limited; only runs in "X"

     If you get error that wish is not found, then install the tk-8.3.rpm package.

   • If you are not able to start X-window above then try -

     bash# export TERM=xterm bash# make menuconfig # Newer, uses ncurses/curses, may fail if not installed If you find scrambled display, then use different terminal emulators like vt100, vt102, vt220 or ansi. The display will be scrambled and will have garbage characters in cases where you use telnet to login to remote linux. In such cases you should use the terminal emulators like vt100, vt220. For example: bash# export TERM=vt220 bash# export TERM=ansi At a lower level of VT, use: bash# export TERM=vt100 bash# make menuconfig # Newer, uses ncurses/curses, may fail if not installed If the menuconfig command fails then try - bash# make config # Old, user unfriendly method !!

   The "make xconfig" or "make menuconfig" brings up a user friendly GUI interface. And "make config" brings up command-line console mode interface. You can load the configuration file from /usr/src/linux/.config (dot config file. Note the dot before config). Click on button "Load Configuration from File". Within 'make xconfig' you must do these (to avoid problems) -

   • VERY IMPORTANT !!! : Select proper CPU type - Pentium 3, AMD K6, Cyrix, Pentium 4, Intel 386, DEC Alpha, PowerPC otherwise kernel compile will fail and even if it compiles, it will not boot!!

   • Select SMP support - whether single CPU or multiple CPUs

   • Filesystems - Select Windows95 Vfat, MSDOS, NTFS as part of kernel and not as loadable modules. (My personal preference, but you are free to pick your own option).

   • Enable the Loadable kernel modules support! With this option you can load/unload the device drivers dynamically on running linux system on the fly. See the Modules chapter at Section 3 .

   Save and Exit "make xconfig". All the options which you selected is now saved into configuration file at /usr/src/linux/.config (dot config file).

5. Dep : And now, do -

   bash# make dep

6. Give a unique name to your new Kernel: You can give a name to your kernel, so that it is unique and does not interfere with others.

   bash# cd /usr/src/linux bash# vi Makefile

   Here look for EXTRAVERSION = -19.8.0_Blah_Blah_Blah and change to something like EXTRAVERSION = -19.8.0MyKernel.26Jan2003

7. Do make: Read the following file (to gain some knowledge about kernel building. Tip: Use the color editor gvim for better readability.

   bash# gvim -R /usr/src/linux/arch/i386/config.in bash# man less bash# less /usr/src/linux/arch/i386/config.in Type 'h' for help and to navigate press i, j, k, l, h or arrow, page up/down keys.

   Now, give the make command -

   bash# cd /usr/src/linux bash# man nohup bash# nohup make bzImage & bash# man tail bash# tail -f nohup.out (.... to monitor the progress) This will put the kernel in /usr/src/linux/arch/i386/boot/bzImage

8. LOADABLE MODULES: Now, while the 'make' is cranking along in the previous step "Do make", you should bring up another new xterm shell window and follow these steps: This step is required ONLY if you had enabled Loadable module support in step "Configure Step" above. Loadable module are located in /lib/modules. You MUST do this step if you enabled or disabled any modules, otherwise you will get 'unresolved symbols' errors during or after kernel boot.

   # Bring up a new Xterm shell window and ... bash# cd /usr/src/linux # Redirect outputs such that you do not overwrite the nohup.out which is still running... bash# nohup make modules 1> modules.out 2> modules.err & bash# make modules_install # Do this, only after the above make command is successful

   This will copy the modules to /lib/modules directory. See the Modules chapter at Section 3 .

9. Now go to Lunch or Bed : Since both the make windows are cranking along, and now, you can go to lunch (chitchat, have nap) or go to bed (have nice Linux dreams in sleep) and when you wake up and come back the system is ready! You can check with command 'less nohup.out' to see the log of output.

   bash# cd /usr/src/linux bash# less nohup.out bash# less modules.err bash# less modules.out If no errors then do: bash# make modules_install

10. bzImage: After bzImage is successful, copy the kernel image to /boot directory. You must copy the new kernel image to /boot directory, otherwise the new kernel MAY NOT boot. You must also copy the config file to /boot area to reflect the kernel image, for documentation purpose.

    bash# cp /usr/src/linux/arch/i386/boot/bzImage /boot/bzImage.myker.26mar2001 # You MUST copy the config file to reflect the corresponding kernel image, # for documentation purpose. bash# cp /usr/src/linux/.config /boot/config-<your_kernelversion_date> # Example: cp /usr/src/linux/.config /boot/config-2.4.18-19.8.0-26mar2001

    NOTE : If you are planning to use the initrd in LILO or GRUB then you may want to build initrd and place it in /boot/initrd*.img. See the Appendix A at Section 15 .

11. Configure GRUB or LILO : There are two options for boot loading under Redhat Linux - GRUB and LILO. Configure GRUB: GRUB is recent and much better tool than LILO and it is my first preference to use GRUB. LILO is an older technology. GRUB differs from bootloaders such as LILO in that "it can lie to MS Windows and make MS Windows believe that it's installed on the first partition even if it's not!!" . So you can keep your current Linux system where it is and install Windows on the side. See the Section 17 file. Configure LILO: LILO is older tool and see the Section 16 to configure LILO.

12. Reboot the machine and at lilo press tab key and type 'myker' If it boots then you did a good job! Otherwise at lilo select your old kernel, boot and re-try all over again. Your old kernel is still INTACT and SAFE at say /boot/vmlinuz-2.0.34-0.6

13. If your new kernel 'myker' boots and works properly, you can create the boot disk. Insert a blank floppy into floppy drive and -

    bash# cd /usr/src/linux bash# make bzdisk See also mkbootdisk - bash# rpm -i mkbootdisk*.rpm bash# man mkbootdisk

14. Build RPMs Optional - You can also build RPM packages of kernel, in case you want to install the new image on several machines.

    make rpm # To build rpm packages

15. Clean: Optional - make clean (If you want to free up disk space)

2.6. Troubleshooting

Having any problems? See the Section 19 .

2.7. Post Kernel Building

See the Section 18 .

2.8. Where to Report Bugs ?

You tried everything above and you think it seems to be a kernel bug. You may want to report this bug so that it will be fixed. You can see the file /usr/src/linux/REPORTING-BUGS and visit the following site - Reporting Bugs for the Linux Kernel .

3.1. Installing the module utilities

You can install the Module Utilities RPM with:

bash# rpm -i /mnt/cdrom/Redhat/RPMS/modutils*.rpm

insmod inserts a module into the running kernel. Modules usually have a .o extension; the example driver mentioned above is called drv_hello.o , so to insert this, one would say ` insmod drv_hello.o '. To see the modules that the kernel is currently using, use lsmod . The output looks like this: blah# lsmod Module: #pages: Used by: drv_hello 1 ` drv_hello ' is the name of the module, it uses one page (4k) of memory, and no other kernel modules depend on it at the moment. To remove this module, use ` rmmod drv_hello '. Note that rmmod wants a module name, not a filename; you get this from lsmod 's listing. The other module utilities' purposes are documented in their manual pages.

3.2. Modules distributed with the kernel

As of version 2.0.30, most of everything is available as a loadable modules. To use them, first make sure that you don't configure them into the regular kernel; that is, don't say y to it during ` make config '. Compile a new kernel and reboot with it. Then, cd to /usr/src/linux again, and do a ` make modules '. This compiles all of the modules which you did not specify in the kernel configuration, and places links to them in /usr/src/linux/modules . You can use them straight from that directory or execute ` make modules_install ', which installs them in /lib/modules/x.y.z , where x.y.z is the kernel release.

This can be especially handy with filesystems. You may not use the minix or msdos filesystems frequently. For example, if I encountered an msdos (shudder) floppy, I would insmod /usr/src/linux/modules/msdos.o , and then rmmod msdos when finished. This procedure saves about 50k of RAM in the kernel during normal operation. A small note is in order for the minix filesystem: you should always configure it directly into the kernel for use in ``rescue'' disks.

3.3. Howto Install Just A Single Module ?

Let us assume that you already did 'make modules' and 'make modules_install'. And later you did 'make clean' to free up disk space. And now, you want to change a "C" file in one of the modules and want to rebuild just that module and copy the module file to /lib/modules. How do you do it? And, you do not want to give 'make modules' as that will rebuild everything and will take about 2 to 3 hours!

You can compile just a single module file (say like foo.o) and install it. For this simply edit the Makefile and change the SUBDIRS to add only those directories you are interested.

A good example is - I found that my default kernel did not include the NTFS filesystem support (I did make clean after make modules. Darn and Damn it!). So, I decided to compile the loadable module of NTFS. I did not want to compile the whole set (as it will take me about 2 hours), so I followed the procedure below and compiled just the fs/ntfs and did 'insmod ntfs'. It just took me about 5 minutes!!

Another example: If I am interested in installing only fs/autofs module, then I do the following :

cd /usr/src/linux mv Makefile Makefile.original cp Makefile.original Makefile.my ln -s Makefile.my Makefile # Because some files underneath still need "Makefile" vi Makefile.my # And comment out the line having 'SUBDIRS' and add the # directory you are interested, for example like fs/autofs as below : #SUBDIRS =kernel drivers mm fs net ipc lib abi crypto SUBDIRS =fs/autofs # Save the file Makefile.my and give - make -f Makefile.my modules # This will create module autofs.o # Now, copy the module object file to destination /lib/modules # DANGER: Do NOT DO THIS - "make -f Makefile.my modules_install" This may # clean up other good ones in /lib/modules !! But just copy as below: cp autofs.o /lib/modules/2.4.18-19.8.0/kernel/fs/autofs # Now, reset everything back to normal rm Makefile # This is a link to Makefile.my ln -s Makefile.original Makefile # Record your changes to the config file for future use # Edit the /usr/src/linux/.config file and set the item as module cd /usr/src/linux mkdir /usr/src/kernelconfigs ; cp /usr/src/linux/.config /usr/src/kernelconfigs/.config.save; cp /usr/src/linux/.config /usr/src/linux/configs/.config.save # ExtraSafe cp /boot/config* /usr/src/linux/configs/ # ExtraSafe vi /usr/src/linux/.config # And change the config parameter. For example in case of my # ntfs module I did CONFIG_NTFS_FS=m to indicate as module.

Learn more about Makefile and make. See the manual for GNU make at

• "http://www.gnu.org/manual/make" .

• University of Utah Makefile "http://www.math.utah.edu/docs/info/make-stds_toc.html"

• University of Hawaii Makefile "http://www.eng.hawaii.edu/Tutor/Make"

• In Linux - man make

• In Linux - info make

Get familiar with the Makefile which makes the modules. The Makefile has module line like

modules: $(patsubst %, _mod_%, $(SUBDIRS))

The patsubst function has the syntax $(patsubst pattern,replacement,text). It uses the percent symbol ([percnt]) the same way pattern rules do - as a string which matches in both the pattern and the replacement text. It searches the text for whitespace-separated words that match the pattern and substitutes the replacement for them.

This makefile includes shell functions as well as standard make functions. The syntax for a shell function is $(shell command). This returns the output of the shell function (stripping new lines).

5.1. What does the kernel do, anyway?

The Unix kernel acts as a mediator for your programs and your hardware. First, it does (or arranges for) the memory management for all of the running programs (processes), and makes sure that they all get a fair (or unfair, if you please) share of the processor's cycles. In addition, it provides a nice, fairly portable interface for programs to talk to your hardware.

There is certainly more to the kernel's operation than this, but these basic functions are the most important to know.

5.2. Why would I want to upgrade my kernel?

Newer kernels generally offer the ability to talk to more types of hardware (that is, they have more device drivers), they can have better process management, they can run faster than the older versions, they could be more stable than the older versions, and they fix silly bugs in the older versions. Most people upgrade kernels because they want the device drivers and the bug fixes.

5.3. What kind of hardware do the newer kernels support?

See the Hardware-HOWTO . Alternatively, you can look at the ` config.in ' file in the linux source, or just find out when you try ` make config '. This shows you all hardware supported by the standard kernel distribution, but not everything that linux supports; many common device drivers (such as the PCMCIA drivers and some tape drivers) are loadable modules maintained and distributed separately.

5.4. What version of gcc and libc do I need?

Linus recommends a version of gcc in the README file included with the linux source. If you don't have this version, the documentation in the recommended version of gcc should tell you if you need to upgrade your libc. This is not a difficult procedure, but it is important to follow the instructions.

5.5. What's a loadable module?

See the Modules chapter at Section 3 .

5.6. How much disk space do I need?

It depends on your particular system configuration. First, the compressed linux source is nearly 14 megabytes large at version 2.2.9. Many sites keep this even after unpacking. Uncompressed and built with a moderate configuration, it takes up another 67 MB.

5.7. How long does it take?

With newer machines, the compilation takes dramatically less time than older ones; an AMD K6-2/300 with a fast disk can do a 2.2.x kernel in about four minutes. As for old Pentiums, 486s, and 386s, if you plan to compile one, be prepared to wait, possibly hours, days..

If this troubles you, and you happen to have a faster machine around to compile on, you can build on the fast machines (assuming you give it the right parameters, that your ulilities are up-to-date, and so on), and then transfer the kernel image to the slower machine.

6.1. Applying a patch

Incremental upgrades of the kernel are distributed as patches. For example, if you have Linux v1.1.45, and you notice that there's a ` patch46.gz ' out there for it, it means you can upgrade to version 1.1.46 through application of the patch. You might want to make a backup of the source tree first (` make clean ' and then ` cd /usr/src; tar zcvf old-tree.tar.gz linux ' will make a compressed tar archive for you.).

So, continuing with the example above, let's suppose that you have ` patch46.gz ' in /usr/src . cd to /usr/src and do a ` zcat patch46.gz [verbar] patch -p0 ' (or ` patch -p0 [lt ] patch46 ' if the patch isn't compressed). You'll see things whizz by (or flutter by, if your system is that slow) telling you that it is trying to apply hunks, and whether it succeeds or not. Usually, this action goes by too quickly for you to read, and you're not too sure whether it worked or not, so you might want to use the -s flag to patch , which tells patch to only report error messages (you don't get as much of the ``hey, my computer is actually doing something for a change!'' feeling, but you may prefer this..). To look for parts which might not have gone smoothly, cd to /usr/src/linux and look for files with a .rej extension. Some versions of patch (older versions which may have been compiled with on an inferior filesystem) leave the rejects with a # extension. You can use ` find ' to look for you; find . -name '*.rej' -print prints all files who live in the current directory or any subdirectories with a .rej extension to the standard output.

If everything went right, do a ` make clean ', ` config ', and ` dep ' as described in sections 3 and 4.

There are quite a few options to the patch command. As mentioned above, patch -s will suppress all messages except the errors. If you keep your kernel source in some other place than /usr/src/linux , patch -p1 (in that directory) will patch things cleanly. Other patch options are well-documented in the manual page.

6.2. If something goes wrong

(Note: this section refers mostly to quite old kernels)

The most frequent problem that used to arise was when a patch modified a file called ` config.in ' and it didn't look quite right, because you changed the options to suit your machine. This has been taken care of, but one still might encounter it with an older release. To fix it, look at the config.in.rej file, and see what remains of the original patch. The changes will typically be marked with ` + ' and ` - ' at the beginning of the line. Look at the lines surrounding it, and remember if they were set to ` y ' or ` n '. Now, edit config.in , and change ` y ' to ` n ' and ` n ' to ` y ' when appropriate. Do a patch -p0 < config.in.rej and if it reports that it succeeded (no fails), then you can continue on with a configuration and compilation. The config.in.rej file will remain, but you can get delete it.

If you encounter further problems, you might have installed a patch out of order. If patch says ` previously applied patch detected: Assume -R? ', you are probably trying to apply a patch which is below your current version number; if you answer ` y ', it will attempt to degrade your source, and will most likely fail; thus, you will need to get a whole new source tree (which might not have been such a bad idea in the first place).

To back out (unapply) a patch, use ` patch -R ' on the original patch.

The best thing to do when patches really turn out wrong is to start over again with a clean, out-of-the-box source tree (for example, from one of the linux-x.y.z.tar.gz files), and start again.

6.3. Getting rid of the .orig files

After just a few patches, the .orig files will start to pile up. For example, one 1.1.51 tree I had was once last cleaned out at 1.1.48. Removing the .orig files saved over a half a meg. find . -name '*.orig' -exec rm -f {} ';' will take care of it for you. Versions of patch which use # for rejects use a tilde instead of .orig .

There are better ways to get rid of the .orig files, which depend on GNU xargs : find . -name '*.orig' | xargs rm or the ``quite secure but a little more verbose'' method: find . -name '*.orig' -print0 | xargs --null rm --

6.4. Other patches

There are other patches (I'll call them ``nonstandard'') than the ones Linus distributes. If you apply these, Linus' patches may not work correctly and you'll have to either back them out, fix the source or the patch, install a new source tree, or a combination of the above. This can become very frustrating, so if you do not want to modify the source (with the possibility of a very bad outcome), back out the nonstandard patches before applying Linus', or just install a new tree. Then, you can see if the nonstandard patches still work. If they don't, you are either stuck with an old kernel, playing with the patch or source to get it to work, or waiting (possibly begging) for a new version of the patch to come out.

How common are the patches not in the standard distribution? You will probably hear of them. I used to use the noblink patch for my virtual consoles because I hate blinking cursors (This patch is (or at least was) frequently updated for new kernel releases.). With most newer device drivers being developed as loadable modules, though, the frequecy of ``nonstandard'' patches is decreasing significantly.

7.1. Redirecting output of the make or patch commands

If you would like logs of what those ` make ' or ` patch ' commands did, you can redirect output to a file. First, find out what shell you're running: ` grep root /etc/passwd ' and look for something like ` /bin/csh '.

If you use sh or bash, (command) 2>&1 | tee (output file) will place a copy of (command) 's output in the file ` (output file) '.

For csh or tcsh, use (command) |& tee (output file)

For rc (Note: you probably do not use rc) it's (command) >[2=1] | tee (output file)

7.2. Conditional kernel install

Other than using floppy disks, there are several methods of testing out a new kernel without touching the old one. Unlike many other Unix flavors, LILO has the ability to boot a kernel from anywhere on the disk (if you have a large (500 MB or above) disk, please read over the LILO documentation on how this may cause problems). So, if you add something similar to image = /usr/src/linux/arch/i386/boot/bzImage label = new_kernel to the end of your LILO configuration file, you can choose to run a newly compiled kernel without touching your old /vmlinuz (after running lilo , of course). The easiest way to tell LILO to boot a new kernel is to press the shift key at bootup time (when it says LILO on the screen, and nothing else), which gives you a prompt. At this point, you can enter ` new_kernel ' to boot the new kernel.

If you wish to keep several different kernel source trees on your system at the same time (this can take up a lot of disk space; be careful), the most common way is to name them /usr/src/linux-x.y.z , where x.y.z is the kernel version. You can then ``select'' a source tree with a symbolic link; for example, ` ln -sf linux-1.2.2 /usr/src/linux ' would make the 1.2.2 tree current. Before creating a symbolic link like this, make certain that the last argument to ln is not a real directory (old symbolic links are fine); the result will not be what you expect.

7.3. Kernel updates

Russell Nelson ( nelson@crynwr.com ) summarizes the changes in new kernel releases. These are short, and you might like to look at them before an upgrade. They are available with anonymous ftp from "ftp://ftp.emlist.com" in pub/kchanges or through the URL "http://www.crynwr.com/kchanges"

8.1. Using the ftpfs

Download the ftpfs and install it on your system. The ftpfs is installed as a module in /lib/modules/2.4.18-19.8.0/kernel/fs/ftpfs/ftpfs.o. And also the command ftpmount is in /usr/bin/ftpmount. And you can do the following:

Login as root (su - root) and run this script:

#!/bin/sh -x # Use this script to mount ftp redhat cdroms rpms directory disk1,2,3 # Built rpm by name ftpfs. # http://lufs.sourceforge.net/main/projects.html # ftpmount --help # Try this: ftpmount [user[:pass]@]host_name[:port][/root_dir] mount_point [-o] # [-uid=id] [gid=id] [fmask=mask] [dmask=mask] #ftpmount anonymous:pass@ftp.kernel.org /mnt/ftpfs #mkdir -p /mnt/ftpfs /mnt/ftpfs/updates /mnt/ftpfs/rpms /mnt/ftpfs/contrib # Redhat ftp mirror sites - http://www.redhat.com/download/mirror.html FTPSITE="csociety-ftp.ecn.purdue.edu" USER="anonymous:pass" ftpmount $USER@$FTPSITE/pub/redhat/redhat /mnt/ftpfs/site ftpmount $USER@$FTPSITE/pub/redhat/redhat/linux/updates/8.0/en/os /mnt/ftpfs/updates ftpmount $USER@$FTPSITE/pub/redhat/redhat/linux/8.0/en/os/i386/RedHat /mnt/ftpfs/rpms ftpmount $USER@$FTPSITE/pub/redhat-contrib /mnt/ftpfs/contrib

8.2. The ftpfs Commands

Before you even start thinking about mounting FTP volumes, make sure you have a decent bandwidth or it's gonna suck.

10.1. vmlinuz and vmlinux

The "vm" stands for "Virtual Memory". Linux supports virtual memory unlike old operating systems like DOS which have a hard limit of 640KB memory. Linux can use the hard disk space as "virtual memory" and hence the name "vm". The vmlinuz is the Linux kernel executable. This is located at /boot/vmlinuz. This can be a soft link to something like /boot/vmlinuz-2.4.18-19.8.0. The vmlinuz is created by "make zImage" and you do "cp /usr/src/linux/arch/i386/linux/boot/zImage /boot/vmlinuz". The vmlinuz is a compressed file of vmlinux. The zImage is there for backward compatibility (smaller kernels). Note that, in near future zImage may be dropped in favor of 'make bzImage' (big zImage). The zImage (vmlinuz) is not just a compressed image, but has gzip decompressor code built into it as well (at the beginning). So you cannot use gunzip or gzip -dc to unpack vmlinuz.

Both zImage and bzImage are compressed with gzip. The kernel includes a mini-gunzip to uncompress the kernel and boot into it. The difference is that the old zImage uncompresses the kernel into low memory (the first 640k), and bzImage uncompresses the kernel into high memory (over 1M).

The vmlinux is the uncompressed built kernel, vmlinuz is the compressed one, that has been made bootable. (Note both names vmlinux and vmlinuz look same except for last letter z). Generally, you don't need to worry about vmlinux, it is just an intermediate step.

The kernel usually makes a bzImage, and stores it in arch/i386/boot, and it is up to the user to copy it to /boot and configure GRUB or LILO.

10.2. Bootloader Files

The .b files are "bootloader" files. they are part of the dance required to get a kernel into memory to begin with. You should NOT touch them.

ls -l /boot/*.b -rw-r--r-- 1 root root 5824 Sep 5 2002 /boot/boot.b -rw-r--r-- 1 root root 612 Sep 5 2002 /boot/chain.b -rw-r--r-- 1 root root 640 Sep 5 2002 /boot/os2_d.b

10.3. Message File

The 'message' file contains the message your bootloader will display, prompting you to choose an OS. So DO NOT touch it.

ls -l /boot/message* -rw-r--r-- 1 root root 23108 Sep 6 2002 /boot/message -rw-r--r-- 1 root root 21282 Sep 6 2002 /boot/message.ja

10.4. initrd.img

See the Appendix A at Section 15 .

10.5. bzImage

The bzImage is the compressed kernel image created with command 'make bzImage' during kernel compile. It important to note that bzImage is not compressed with bzip2 !! The name bz in bzImage is misleading!! It stands for "Big Zimage". The "b" in bzImage is "big". Both zImage and bzImage are compressed with gzip. The kernel includes a mini-gunzip to uncompress the kernel and boot into it. The difference is that the old zImage uncompresses the kernel into low memory (the first 640k), and bzImage uncompresses the kernel into high memory (over 1M). The only problem is that there are a very few machines where bzImage is known to have problems (because the machines are buggy). The bzImage actually boots faster, but other than that, there's no difference in the way the system *runs*. The rule is that if all drivers cannot fit into the zImage, then you need to modularize more.

If the kernel is small, it will work as both a zImage and a bzImage, and the booted system runs the same way. A big kernel will work as a bzImage, but not as a zImage. Both bootimages are gzipped, (bzImage is not bzipped as the name would suggest), but are put together and loaded differently, that allows the kernel to load in higher address space, that does not limit it to lower memory in the pathetic intel architecture. So why have both? Backward compatability. Some older lilos and loadlins don't handle the bzImage format. Note, they *boot* differently, but *run* the same. There is a lot of misinformation given out about what a bzImage file is (mostly about it being bzip2ed).

10.6. module-info

This file "module-info" is a symbolic link:

$ uname -r 2.4.18-19.8.0custom # ls -l /boot/module-info* lrwxrwxrwx 1 root root 25 Jan 26 10:44 /boot/module-info -> module-info-2.4.18-19.8.0 -rw-r--r-- 1 root root 15436 Sep 4 2002 /boot/module-info-2.4.18-14 -rw-r--r-- 1 root root 15436 Jan 26 01:29 /boot/module-info-2.4.18-19.8.0

Note above that it is not a requirement is make module-info symlink to a kernel specific file like the way System-map and vmlinuz is required. It's just a text file so as long as module-info list is recent, you'll be fine. Before removing all the stock RH kernels from your system, you should make a backup of this file:

# cp /boot/module-info-2.4.20-19.9 /boot/module-info-2.4.20-19.9.backup

It should be safe to do this as module-info rarely changes within the same point release of RH kernels.

This file 'module-info' is created by anaconda/utils/modlist (specific to Redhat Linux Anaconda installer). Other Linux distributions may be having equivalent command. Refer to your Linux distributor's manual pages.

See this script and search for "module-info" updmodules .

Below is a cut from this script:

#!/bin/bash # updmodules.sh MODLIST=$PWD/../anaconda/utils/modlist MODINFO=$KERNELROOT/boot/module-info-$version -- snip cut blah blah blah -- snip cut # create the module-info file $MODLIST --modinfo-file $MODINFO --ignore-missing --modinfo \ $(ls *.o | sed 's/\.o$//') > ../modinfo

The program anaconda/utils/modlist is located in anaconda-runtime*.rpm on the Redhat CDROM

cd /mnt/cdrom/RedHat/RPMS rpm -i anaconda-8.0-4.i386.rpm rpm -i anaconda-runtime-8.0-4.i386.rpm ls -l /usr/lib/anaconda-runtime/modlist

Get the source code for anaconda/utils/modlist.c from anaconda*.src.rpm at "http://www.rpmfind.net/linux/rpm2html/search.php?query=anaconda" Read online at modlist.c . .

The file 'module-info' is generated during the compile. It is an information file that is at least used during filing proper kernel OOPS reports. It is a list of the module entry points. It may also be used by depmod in building the tables that are used by insmod and its kith and kin. This includes dependancy information for other modules needed to be loaded before any other given module, etc.

Bottom line is: "Don't remove this file module-info."

Some points about module-info:

• Is provided by the kernel rpms (built by anaconda-runtime*.rpm)

• Is a link to module-info-{kernel-version}

• Contains information about all available modules (at least those included in the default kernel config.)

• Important to anaconda - in anaconda/utils/modlist command.

• Might be used by kudzu to determine default parameters for modules when it creates entries in /etc/modules.conf. If you move module-info out of the way, shut down, install a new network card, and re-boot then kudzu would complain loudly. Look at the kudzu source code.

10.7. config

Everytime you compile and install the kernel image in /boot, you should also copy the corresponding config file to /boot area, for documentation and future reference. Do NOT touch or edit these files!!

ls -l /boot/config-* -rw-r--r-- 1 root root 42111 Sep 4 2002 /boot/config-2.4.18-14 -rw-r--r-- 1 root root 42328 Jan 26 01:29 /boot/config-2.4.18-19.8.0 -rw-r--r-- 1 root root 51426 Jan 25 22:21 /boot/config-2.4.18-19.8.0BOOT -rw-r--r-- 1 root root 52328 Jan 28 03:22 /boot/config-2.4.18-19.8.0-26mar2003

10.8. grub

If you are using GRUB, then there will be 'grub' directory.

ls /boot/grub device.map ffs_stage1_5 menu.lst reiserfs_stage1_5 stage2 e2fs_stage1_5 grub.conf minix_stage1_5 splash.xpm.gz vstafs_stage1_5 fat_stage1_5 jfs_stage1_5 stage1 xfs_stage1_5

See also Section 17 file.

10.9. System.map

System.map is a "phone directory" list of function in a particular build of a kernel. It is typically a symlink to the System.map of the currently running kernel. If you use the wrong (or no) System.map, debugging crashes is harder, but has no other effects. Without System.map, you may face minor annoyance messages.

Do NOT touch the System.map files.

ls -ld /boot/System.map* lrwxrwxrwx 1 root root 30 Jan 26 19:26 /boot/System.map -> System.map-2.4.18-19.8.0custom -rw-r--r-- 1 root root 501166 Sep 4 2002 /boot/System.map-2.4.18-14 -rw-r--r-- 1 root root 510786 Jan 26 01:29 /boot/System.map-2.4.18-19.8.0 -rw-r--r-- 1 root root 331213 Jan 25 22:21 /boot/System.map-2.4.18-19.8.0BOOT -rw-r--r-- 1 root root 503246 Jan 26 19:26 /boot/System.map-2.4.18-19.8.0custom

How The Kernel Symbol Table Is Created ? System.map is produced by 'nm vmlinux' and irrelevant or uninteresting symbols are grepped out, When you compile the kernel, this file 'System.map' is created at /usr/src/linux/System.map. Something like below:

nm /boot/vmlinux-2.4.18-19.8.0 > System.map # Below is the line from /usr/src/linux/Makefile nm vmlinux | grep -v '\(compiled\)\|\(\.o$$\)\|\( [aUw] \)\|\(\.\.ng$$\)\|\(LASH[RL]DI\)' | sort > System.map cp /usr/src/linux/System.map /boot/System.map-2.4.18-14 # For v2.4.18

From "http://www.dirac.org/linux/systemmap.html"

12.1. Source Code of 'apt-get'

You can download and recompile the apt-get source code for your distro. Download source code of apt-get from http://ftp.freshrpms.net/pub/freshrpms/redhat/9/apt .

12.2. The 'rpmfind' Tool

Apart from apt-get you can also use rpmfind tool in redhat. The rpmfind tool has some similarities with apt-get. Visit the rpmfind site at : http://rpmfind.net/linux/rpmfind . The rpmfind is a utility that will find, install, autoupgrade RPM files on rufus to your local computer. The main site of rpmfind "search site" is http://rpmfind.net .

13.1. References for Boot Process

Refer to following resources :

• The Linux Boot Process

• Bootdisks and Boot Process

• Linux Boot Process - by San Gabreil LUG

• Boot Process (Netmag)

• Boot Process (LUG Victoria)

14.1. Acrobat PDF format

PDF file can be generated from postscript file using either acrobat distill or Ghostscript . And postscript file is generated from DVI which in turn is generated from LaTex file. You can download distill software from "http://www.adobe.com" . Given below is a sample session:

bash$ man sgml2latex bash$ sgml2latex filename.sgml bash$ man dvips bash$ dvips -o filename.ps filename.dvi bash$ distill filename.ps bash$ man ghostscript bash$ man ps2pdf bash$ ps2pdf input.ps output.pdf bash$ acroread output.pdf &

Or you can use Ghostscript command ps2pdf . ps2pdf is a work-alike for nearly all the functionality of Adobe's Acrobat Distiller product: it converts PostScript files to Portable Document Format (PDF) files. ps2pdf is implemented as a very small command script (batch file) that invokes Ghostscript, selecting a special "output device" called pdfwrite . In order to use ps2pdf, the pdfwrite device must be included in the makefile when Ghostscript was compiled; see the documentation on building Ghostscript for details.

14.2. Convert Linuxdoc to Docbook format

This document is written in linuxdoc SGML format. The Docbook SGML format supercedes the linuxdoc format and has lot more features than linuxdoc. The linuxdoc is very simple and is easy to use. To convert linuxdoc SGML file to Docbook SGML use the program ld2db.sh and some perl scripts. The ld2db output is not 100[percnt] clean and you need to use the clean_ld2db.pl perl script. You may need to manually correct few lines in the document.

• Download ld2db program from "http://www.dcs.gla.ac.uk/~rrt/docbook.html" or from "http://milkyway.has.it" and Milkyway Galaxy site

• Download the cleanup_ld2db.pl perl script from from "http://milkyway.has.it" and Milkyway Galaxy site

		bash$ ld2db.sh file-linuxdoc.sgml db.sgml
		bash$ cleanup.pl db.sgml > db_clean.sgml
		bash$ gvim db_clean.sgml 
		bash$ docbook2html db.sgml
        

14.3. Convert to MS WinHelp format

You can convert the SGML howto document to Microsoft Windows Help file, first convert the sgml to html using:

bash$ sgml2html xxxxhowto.sgml (to generate html file) bash$ sgml2html -split 0 xxxxhowto.sgml (to generate a single page html file)

Then use the tool HtmlToHlp . You can also use sgml2rtf and then use the RTF files for generating winhelp files.

14.4. Reading various formats

In order to view the document in dvi format, use the xdvi program. The xdvi program is located in tetex-xdvi*.rpm package in Redhat Linux which can be located through ControlPanel [verbar] Applications [verbar] Publishing [verbar] TeX menu buttons. To read dvi document give the command -

xdvi -geometry 80x90 howto.dvi man xdvi

And resize the window with mouse. To navigate use Arrow keys, Page Up, Page Down keys, also you can use 'f', 'd', 'u', 'c', 'l', 'r', 'p', 'n' letter keys to move up, down, center, next page, previous page etc. To turn off expert menu press 'x'.

You can read postscript file using the program 'gv' (ghostview) or 'ghostscript'. The ghostscript program is in ghostscript*.rpm package and gv program is in gv*.rpm package in Redhat Linux which can be located through ControlPanel [verbar] Applications [verbar] Graphics menu buttons. The gv program is much more user friendly than ghostscript. Also ghostscript and gv are available on other platforms like OS/2, Windows 95 and NT, you view this document even on those platforms.

• Get ghostscript for Windows 95, OS/2, and for all OSes from "http://www.cs.wisc.edu/~ghost"

To read postscript document give the command -

gv howto.ps ghostscript howto.ps

You can read HTML format document using Netscape Navigator, Microsoft Internet explorer, Redhat Baron Web browser or any of the 10 other web browsers.

You can read the latex, LyX output using LyX a X-Windows front end to latex.

15.1. Using mkinitrd

The mkinitrd utility creates an initrd image in a single command. This is command is peculiar to RedHat. There may be equivalent command of mkinitrd in other distributions of Linux. This is very convenient utility.

You can read the mkinitrd man page.

/sbin/mkinitrd --help # Or simply type 'mkinitrd --help' usage: mkinitrd [--version] [-v] [-f] [--preload <module>] [--omit-scsi-modules] [--omit-raid-modules] [--omit-lvm-modules] [--with=<module>] [--image-version] [--fstab=<fstab>] [--nocompress] [--builtin=<module>] [--nopivot] <initrd-image> <kernel-version> (example: mkinitrd /boot/initrd-2.2.5-15.img 2.2.5-15) # Read the online manual page with ..... man mkinitrd su - root # The command below creates the initrd image file mkinitrd ./initrd-2.4.18-19.8.0custom.img 2.4.18-19.8.0custom ls -l initrd-2.4.18-19.8.0custom.img -rw-r--r-- 1 root root 127314 Mar 19 21:54 initrd-2.4.18-19.8.0custom.img cp ./initrd-2.4.18-19.8.0custom.img /boot

See the following sections for the manual method of creating an initrd image.

15.2. Kernel Docs

To create /boot/initrd.img see the documentation at /usr/src/linux/Documentation/initrd.txt and see also Loopback-Root-mini-HOWTO .

15.3. Linuxman Book

A cut from "http://www.linuxman.com.cy/rute/node1.html" chapter 31.7.

SCSI Installation Complications and initrd

Some of the following descriptions may be difficult to understand without knowledge of kernel modules explained in Chapter 42. You may want to come back to it later.

Consider a system with zero IDE disks and one SCSI disk containing a LINUX installation. There are BIOS interrupts to read the SCSI disk, just as there were for the IDE, so LILO can happily access a kernel image somewhere inside the SCSI partition. However, the kernel is going to be lost without a kernel module [lsqb ]See Chapter 42. The kernel doesn't support every possible kind of hardware out there all by itself. It is actually divided into a main part (the kernel image discussed in this chapter) and hundreds of modules (loadable parts that reside in /lib/modules/) that support the many type of SCSI, network, sound etc., peripheral devices.] that understands the particular SCSI driver. So although the kernel can load and execute, it won't be able to mount its root file system without loading a SCSI module first. But the module itself resides in the root file system in /lib/modules/. This is a tricky situation to solve and is done in one of two ways: either (a) using a kernel with preenabled SCSI support or (b) using what is known as an initrd preliminary root file system image.

The first method is what I recommend. It's a straightforward (though time-consuming) procedure to create a kernel with SCSI support for your SCSI card built-in (and not in a separate module). Built-in SCSI and network drivers will also autodetect cards most of the time, allowing immediate access to the device--they will work without being given any options [lsqb ]Discussed in Chapter 42.] and, most importantly, without your having to read up on how to configure them. This setup is known as compiled-in support for a hardware driver (as opposed to module support for the driver). The resulting kernel image will be larger by an amount equal to the size of module. Chapter 42 discusses such kernel compiles.

The second method is faster but trickier. LINUX supports what is known as an initrd image ( initial rAM disk image). This is a small, +1.5 megabyte file system that is loaded by LILO and mounted by the kernel instead of the real file system. The kernel mounts this file system as a RAM disk, executes the file /linuxrc, and then only mounts the real file system.

31.6 Creating an initrd Image

Start by creating a small file system. Make a directory [nbsp ]/initrd and copy the following files into it.

drwxr-xr-x 7 root root 1024 Sep 14 20:12 initrd/ drwxr-xr-x 2 root root 1024 Sep 14 20:12 initrd/bin/ -rwxr-xr-x 1 root root 436328 Sep 14 20:12 initrd/bin/insmod -rwxr-xr-x 1 root root 424680 Sep 14 20:12 initrd/bin/sash drwxr-xr-x 2 root root 1024 Sep 14 20:12 initrd/dev/ crw-r--r-- 1 root root 5, 1 Sep 14 20:12 initrd/dev/console crw-r--r-- 1 root root 1, 3 Sep 14 20:12 initrd/dev/null brw-r--r-- 1 root root 1, 1 Sep 14 20:12 initrd/dev/ram crw-r--r-- 1 root root 4, 0 Sep 14 20:12 initrd/dev/systty crw-r--r-- 1 root root 4, 1 Sep 14 20:12 initrd/dev/tty1 crw-r--r-- 1 root root 4, 1 Sep 14 20:12 initrd/dev/tty2 crw-r--r-- 1 root root 4, 1 Sep 14 20:12 initrd/dev/tty3 crw-r--r-- 1 root root 4, 1 Sep 14 20:12 initrd/dev/tty4 drwxr-xr-x 2 root root 1024 Sep 14 20:12 initrd/etc/ drwxr-xr-x 2 root root 1024 Sep 14 20:12 initrd/lib/ -rwxr-xr-x 1 root root 76 Sep 14 20:12 initrd/linuxrc drwxr-xr-x 2 root root 1024 Sep 14 20:12 initrd/loopfs/

On my system, the file initrd/bin/insmod is the statically linked [lsqb ]meaning it does not require shared libraries.] version copied from /sbin/insmod.static--a member of the modutils-2.3.13 package. initrd/bin/sash is a statically linked shell from the sash-3.4 package. You can recompile insmod from source if you don't have a statically linked version. Alternatively, copy the needed DLLs from /lib/ to initrd/lib/. (You can get the list of required DLLs by running ldd /sbin/insmod. Don't forget to also copy symlinks and run strip -s {lib} to reduce the size of the DLLs.)

Now copy into the initrd/lib/ directory the SCSI modules you require. For example, if we have an Adaptec AIC-7850 SCSI adapter, we would require the aic7xxx.o module from /lib/modules/{version}/scsi/aic7xxx.o. Then, place it in the initrd/lib/ directory.

-rw-r--r-- 1 root root 129448 Sep 27 1999 initrd/lib/aic7xxx.o

The file initrd/linuxrc should contain a script to load all the modules needed for the kernel to access the SCSI partition. In this case, just the aic7xxx module [lsqb ] insmod can take options such as the IRQ and IO-port for the device. See Chapter 42.]:

#!/bin/sash aliasall echo "Loading aic7xxx module" insmod /lib/aic7xxx.o

Now double-check all your permissions and then chroot to the file system for testing.

chroot ~/initrd /bin/sash /linuxrc

Now, create a file system image similar to that in Section 19.9:

dd if=/dev/zero of=~/file-inird count=2500 bs=1024 losetup /dev/loop0 ~/file-inird mke2fs /dev/loop0 mkdir ~/mnt mount /dev/loop0 ~/mnt cp -a initrd/* ~/mnt/ umount ~/mnt losetup -d /dev/loop0

Finally, gzip the file system to an appropriately named file:

gzip -c ~/file-inird > initrd-<kernel-version>

31.7 Modifying lilo.conf for initrd

Your lilo.conf file can be changed slightly to force use of an initrd file system. Simply add the initrd option. For example:

boot=/dev/sda prompt timeout = 50 compact vga = extended linear image = /boot/vmlinuz-2.2.17 initrd = /boot/initrd-2.2.17 label = linux root = /dev/sda1 read-only

Notice the use of the linear option. This is a BIOS trick that you can read about in lilo(5). It is often necessary but can make SCSI disks nonportable to different BIOSs (meaning that you will have to rerun lilo if you move the disk to a different computer).

16.1. Resources on LILO

See also following documents:

• http://www.tldp.org/HOWTO/mini/LILO.html

• See the documentation of Lilo on your Linux system :

  # Use the kghostview, ghostview or gv command kghostview /usr/share/doc/lilo-21.4.4/doc/user.ps # To read in HTML format do this - mkdir $HOME/lilodocs cd $HOME/lilodocs cp /usr/share/doc/lilo-21.4.4/doc/user.tex . latex2html user # This creates the html files in user directory

• Section 17 GRUB Conf file.

• "http://www.linuxdoc.org/HOWTO/LILO-crash-rescue-HOWTO.html" .

16.2. Troubleshooting LILO

The beeper error codes :

2 short beeps : POST not correct. Error in a Harware test. 1 short & 2 long beeps : video error. 1) Video ROM BIOS, parity error. 2) Problem with the horizontal retour from the video adapter. 1 long & 3 short beeps: video error. 1) videocard defect. 2) wrong detection from used monitor. 3) Video RAM error. 1 long beep : POST was correct If there is a posterror, there is a hardwareproblem. Check the extentioncards for a bad contact

See also http://www.preggers.easynet.be/lilo.html

If you get problems in LILO, refer to following tips. During boot if you get error "L0101010101010101 ....", then do this

• Use your favorite text editor to open /etc/lilo.conf

  # Find the line that reads linear # Comment it out. Change it to read # linear Save and rerun lilo.

• You need to have your booting partion below the 8 gb mark. If you have a program like parition magic or Mandrake's DiskDrake utility you can easily fix this.

• 01 is dram refresh error. When you get the L 01 simply reboot again with CTRL+ATL+DEL (but you should not power off just do ctrl+alt+del). This may correct the problem.

16.3. Sample on LILO

Always give a date extension to the filename, because it tells you when you built the kernel, as shown below:

bash# man lilo bash# man lilo.conf And edit /etc/lilo.conf file and put these lines - image=/boot/bzImage.myker.26mar2001 label=myker root=/dev/hda1 read-only You can check device name for 'root=' with the command - bash# df / Now give - bash# lilo bash# lilo -q

You must re-run lilo even if the entry 'myker' exists, everytime you create a new bzImage.

Given below is a sample /etc/lilo.conf file. You should follow the naming conventions like ker2217 (for kernel 2.2.17), ker2214 (for kernel 2.2.14). You can have many kernel images on the same /boot system. On my machine I have something like:

boot=/dev/hda map=/boot/map install=/boot/boot.b prompt timeout=50 default=firewall image=/boot/vmlinuz-2.2.14-5.0 label=ker2214 read-only root=/dev/hda9 image=/boot/vmlinuz-2.2.17-14 label=ker2217 read-only root=/dev/hda9 #image=/usr/src/linux/arch/i386/boot/bzImage # label=myker # root=/dev/hda7 # read-only image=/boot/bzImage.myker.11feb2001 label=myker11feb root=/dev/hda9 read-only image=/boot/bzImage.myker.01jan2001 label=myker01jan root=/dev/hda9 read-only image=/boot/bzImage.myker-firewall.16mar2001 label=firewall root=/dev/hda9 read-only

17.1. References on GRUB

See

• "http://www.tldp.org/HOWTO/Linux+Win9x+Grub-HOWTO/intro.html"

• GNU GRUB "http://www.gnu.org/software/grub"

• Redhat Manual .

• Multiboot-with-GRUB minihowto

• Grub Manual

	bash# man grub
	bash# man grubby   # (command line tool for configuring grub, lilo, and elilo)
	bash# man grub-install
      

17.2. Tips On GRUB

In Redhat Linux, during grub display, just type c for command-line option of GRUB:

To boot Linux do this: grub> help grub> root (hd1,1): Filesystem is type ext2fs, partition type 0x83 grub> root (hd1,0) grub> kernel / <Press-TAB-KEY> This will list all files grub> kernel /boot <Press-TAB-KEY> This will list all files in /boot grub> kernel /boot/vmlinuz grub> boot

See also the GRUB Manual . To boot MS Windows 95/2000 etc do this: If you want to boot an unsupported operating system (e.g. Windows 95), chain-load a boot loader for the operating system. Normally, the boot loader is embedded in the boot sector of the partition on which the operating system is installed.

grub> help grub> help rootnoverify grub> rootnoverify (hd0,0) grub> makeactive grub> chainloader +1 grub> boot

17.3. Sample GRUB Conf File

# grub.conf generated by anaconda # # Note that you do not have to rerun grub after making changes to this file # NOTICE: You do not have a /boot partition. This means that # all kernel and initrd paths are relative to /, eg. # root (hd0,8) # kernel /boot/vmlinuz-version ro root=/dev/hda9 # initrd /boot/initrd-version.img #boot=/dev/hda # By default boot the second entry default=1 # Fallback to the first entry. fallback 0 # Boot automatically after 2 minutes timeout=120 splashimage=(hd0,8)/boot/grub/splash.xpm.gz title Windows 2000 unhide (hd0,0) hide (hd0,1) hide (hd0,2) rootnoverify (hd0,0) chainloader +1 makeactive title Red Hat Linux (2.4.18-19.8.0.19mar2003) root (hd0,8) kernel /boot/bzImage.2.4.18-19.8.0.19mar2003 ro root=LABEL=/ hdd=ide-scsi initrd /boot/initrd-2.4.18-19.8.0custom.img.19mar03 title Red Hat Linux (2.4.18-19.8.0custom) root (hd0,8) kernel /boot/vmlinuz-2.4.18-19.8.0custom ro root=LABEL=/ hdd=ide-scsi initrd /boot/initrd-2.4.18-19.8.0custom.img title Red Hat Linux (2.4.18-14) root (hd0,8) kernel /boot/vmlinuz-2.4.18-14 ro root=LABEL=/ hdd=ide-scsi initrd /boot/initrd-2.4.18-14.img title MyKernel.26jan03 (Red Hat Linux 2.4.18-14) root (hd0,8) kernel /boot/bzImage.myker.26jan03 ro root=LABEL=/ hdd=ide-scsi initrd /boot/initrd-2.4.18-19.8.0.img title Windows 98 hide (hd0,0) hide (hd0,1) unhide (hd0,2) rootnoverify (hd0,2) chainloader +1 makeactive title DOS 6.22 hide (hd0,0) unhide (hd0,1) hide (hd0,2) rootnoverify (hd0,1) chainloader +1 makeactive title Partition 2 (floppy) hide (hd0,0) unhide (hd0,1) hide (hd0,2) chainloader (fd0)+1 title Partition 3 (floppy) hide (hd0,0) hide (hd0,1) unhide (hd0,2) chainloader (fd0)+1

19.1. Kernel Compiles OK but make modules fail

Sympton: The kernel compiles ok producing bzImage but 'make modules' fails.

Solution: This problem is most tricky - there can be many subtle reasons. May be related to Linux distro or dependencies of packages are not uptodate. This one is very peculiar of Redhat distribution but may happen to other distributions. There are some "left over" files which are hanging and causing problems. The remedy is to do 'make mrproper' and 'make clean' and then do 'make modules'. But you may want to copy the saved config file as shown below:

bash# cd /usr/src/linux bash# mkdir /usr/src/kernelconfigs ; bash# cp /usr/src/linux/.config /usr/src/kernelconfigs/.config.save; bash# cp /usr/src/linux/.config /usr/src/linux/configs/.config.save # ExtraSafe bash# cp /boot/config* /usr/src/linux/configs/ # ExtraSafe bash# make clean bash# make mrproper # "MUST DO THIS mrproper", otherwise you will face hell lot of problems !! bash# make clean bash# cp /usr/src/kernelconfigs/.config.save .config # In case you want to reuse the config file ??

19.2. Compiles OK but does not boot

Sympton: If the kernel compiles ok but booting never works and it always complains with a kernel panic about /sbin/modprobe.

Solution: You did not create initrd image file. See the Appendix A at Section 15 .

Also, you must do 'make modules' and 'make modules_install' in addition to creating the initrd image file. Even if you had run 'make modules' before, try running again for the second time (does not hurt). Give 'make modules' and 'make modules_install' once again to make sure for certain that all the loadable modules are put in place.

19.3. The System Hangs at LILO

Sympton: After you build the kernel and reboot, the system hangs just before LILO.

Reason: Probably you did not set the BIOS to pick up the proper Primary Master IDE and Secondary Slave IDE hard disk partition.

Solution: Power on the machine and press DEL key to do setup of the BIOS (Basic Input Output system). Select the IDE settings and set proper primary hard disk partition and slave drives. When the system boots it looks for the primary IDE hard disk and the Master Boot Record partition. It reads the MBR and starts loading the Linux Kernel from the hard disk partition.

19.4. No init found

The following mistake is commited very frequently by new users.

If your new kernel does not boot and you get -

Warning: unable to open an initial console Kernel panic: no init found. Try passing init= option to kernel

The problem is that you did not set the "root=" parameter properly in the /etc/lilo.conf. In my case, I used root=/dev/hda1 which is having the root partition "/". You must properly point the root device in your lilo.conf, it can be like /dev/hdb2 or /dev/hda7.

There may be errors just before this Kernel panic. Look for and read any error messages just above the like 'Kernel panic:'. The failure may be due to any error messages just before this one (it is cummulative effect). For example, before the 'Kernel panic' error you might have got error like 'kernel-module version mismatch' or 'something-else-some-other-error-message'. Try to correct the FIRST error reported by the system.

The kernel looks for the init command which is located in /sbin/init. And /sbin directory lives on the root partition. For details see -

bash# man init

See the Section 17 file and see the Section 16 .

19.5. Lot of Compile Errors

The 'make', 'make bzImage', 'make modules' or 'make modules_install' gives compile problems. You should give 'make mrproper' before doing make.

bash# make clean && make mrproper # "MUST DO THIS mrproper", otherwise you will face hell lot of problems !!

If this problem persists, then try menuconfig instead of xconfig. Sometimes GUI version xconfig causes some problems:

bash# export TERM=VT100 bash# make menuconfig # Newer, uses ncurses/curses, may fail if not installed

19.6. The 'depmod' gives "Unresolved symbol error messages"

When you run depmod it gives "Unresolved symbols". A sample error message is given here to demonstrate the case:

bash$ su - root bash# man depmod bash# depmod depmod: *** Unresolved symbols in /lib/modules/version/kernel/drivers/md/linear.o depmod: *** Unresolved symbols in /lib/modules/version/kernel/drivers/md/multipath.o depmod: *** Unresolved symbols in /lib/modules/version/kernel/drivers/md/raid0.o depmod: *** Unresolved symbols in /lib/modules/version/kernel/drivers/md/raid1.o depmod: *** Unresolved symbols in /lib/modules/version/kernel/drivers/md/raid5.o

Reason: You did not make modules and install the modules after building the new kernel with "make bzImage" .

Solution: After you build the new kernel, you must do:

bash$ su - root bash# cd /usr/src/linux bash# make modules bash# make modules_install

19.7. Kernel Does Not Load Module - "Unresolved symbols" Error Messages

When you boot kernel and system tries to load any modules and you get "Unresolved symbol : __some_function_name" then it means that you did not clean compile the modules and kernel. It is mandatory that you should do make clean and make the modules. Do this -

bash# cd /usr/src/linux bash# make dep bash# make clean bash# make mrproper # "MUST DO THIS mrproper", otherwise you will face hell lot of problems !! bash# make clean bash# nohup make bzImage & bash# tail -f nohup.out (.... to monitor the progress) bash# make modules bash# make modules_install

19.8. Kernel fails to load a module

If the kernel fails to load a module (say loadable module for network card or other devices), then you may want to try to build the driver for device right into the kernel. Sometimes loadable module will NOT work and the driver needs to be built right inside the kernel. For example - some network cards do not support loadable module feature - you MUST build the driver of the network card right into linux kernel. Hence, in 'make xconfig' you MUST not select loadable module for this device.

19.9. Loadable modules

You can install default loadable modules with -

The step given below may not be required but is needed ONLY FOR EMERGENCIES where your /lib/modules files are damaged. If you already have the /lib/modules directory and in case you want replace them use the --force to replace the package and select appropriate cpu architecture.

For new versions of linux redhat linux 6.0 and later, the kernel modules are included with kernel-2.2*.rpm. Install the loadable modules and the kernel with

This will list the already installed package. bash# rpm -qa | grep -i kernel bash# rpm -U --force /mnt/cdrom/Redhat/RPMS/kernel-2.2.14-5.0.i686.rpm (or) bash# rpm -U --force /mnt/cdrom/Redhat/RPMS/kernel-2.2.14-5.0.i586.rpm (or) bash# rpm -U --force /mnt/cdrom/Redhat/RPMS/kernel-2.2.14-5.0.i386.rpm

This is only for old versions of redhat linux 5.2 and before. Boot new kernel and install the loadable modules from RedHat Linux "contrib" cdrom

bash# rpm -i /mnt/cdrom/contrib/kernel-modules*.rpm ....(For old linux systems which do not have insmod pre-installed)

19.10. See Kernel Documentations

More problems. You can read the /usr/src/linux/README (at least once) and also /usr/src/linux/Documentation.

bash [/] # cd /usr/src/linux/Documentation bash [/usr/src/linux/Documentation] # ls *.txt binfmt_misc.txt ioctl-number.txt nbd.txt serial-console.txt cachetlb.txt IO-mapping.txt nfsroot.txt sgi-visws.txt cciss.txt IRQ-affinity.txt nmi_watchdog.txt smart-config.txt computone.txt isapnp.txt oops-tracing.txt smp.txt cpqarray.txt java.txt paride.txt sonypi.txt devices.txt kernel-doc-nano-HOWTO.txt parport-lowlevel.txt specialix.txt digiboard.txt kernel-docs.txt parport.txt spinlocks.txt digiepca.txt kernel-parameters.txt pci.txt stallion.txt DMA-mapping.txt kmod.txt pcwd-watchdog.txt svga.txt dnotify.txt locks.txt pm.txt swsusp.txt exception.txt logo.txt ramdisk.txt sx.txt floppy.txt magic-number.txt riscom8.txt sysrq.txt ftape.txt mandatory.txt rtc.txt unicode.txt hayes-esp.txt mca.txt SAK.txt VGA-softcursor.txt highuid.txt md.txt sched-coding.txt watchdog-api.txt i810_rng.txt memory.txt sched-design.txt watchdog.txt ide.txt modules.txt scsi-generic.txt zorro.txt initrd.txt mtrr.txt scsi.txt

19.11. make clean

If your new kernel does really weird things after a routine kernel upgrade, chances are you forgot to make clean before compiling the new kernel. Symptoms can be anything from your system outright crashing, strange I/O problems, to crummy performance. Make sure you do a make dep , too.

19.12. Huge or slow kernels

If your kernel is sucking up a lot of memory, is too large, and/or just takes forever to compile even when you've got your new Quadbazillium-III/4400 working on it, you've probably got lot of unneeded stuff (device drivers, filesystems, etc) configured. If you don't use it, don't configure it, because it does take up memory. The most obvious symptom of kernel bloat is extreme swapping in and out of memory to disk; if your disk is making a lot of noise and it's not one of those old Fujitsu Eagles that sound like like a jet landing when turned off, look over your kernel configuration.

You can find out how much memory the kernel is using by taking the total amount of memory in your machine and subtracting from it the amount of ``total mem'' in /proc/meminfo or the output of the command ` free '.

19.13. The parallel port doesn't work/my printer doesn't work

Configuration options for PCs are: First, under the category `General Setup', select `Parallel port support' and `PC-style hardware'. Then under `Character devices', select `Parallel printer support'.

Then there are the names. Linux 2.2 names the printer devices differently than previous releases. The upshot of this is that if you had an lp1 under your old kernel, it's probably an lp0 under your new one. Use ` dmesg ' or look through the logs in /var/log to find out.

19.14. Kernel doesn't compile

If it does not compile, then it is likely that a patch failed, or your source is somehow corrupt. Your version of gcc also might not be correct, or could also be corrupt (for example, the include files might be in error). Make sure that the symbolic links which Linus describes in the README are set up correctly. In general, if a standard kernel does not compile, something is seriously wrong with the system, and reinstallation of certain tools is probably necessary.

In some cases, gcc can crash due to hardware problems. The error message will be something like ``xxx exited with signal 15'' and it will generally look very mysterious. I probably would not mention this, except that it happened to me once - I had some bad cache memory, and the compiler would occasionally barf at random. Try reinstalling gcc first if you experience problems. You should only get suspicious if your kernel compiles fine with external cache turned off, a reduced amount of RAM, etc.

It tends to disturb people when it's suggested that their hardware has problems. Well, I'm not making this up. There is an FAQ for it -- it's at "http://www.bitwizard.nl/sig11" .

19.15. New version of the kernel doesn't seem to boot

You did not run LILO, or it is not configured correctly. One thing that ``got'' me once was a problem in the config file; it said ` boot = /dev/hda1 ' instead of ` boot = /dev/hda ' (This can be really annoying at first, but once you have a working config file, you shouldn't need to change it.).

19.16. You forgot to run LILO, or system doesn't boot at all

Ooops! The best thing you can do here is to boot off of a floppy disk or CDROM and prepare another bootable floppy (such as ` make zdisk ' would do). You need to know where your root ( / ) filesystem is and what type it is (e.g. second extended, minix). In the example below, you also need to know what filesystem your /usr/src/linux source tree is on, its type, and where it is normally mounted.

In the following example, / is /dev/hda1 , and the filesystem which holds /usr/src/linux is /dev/hda3 , normally mounted at /usr . Both are second extended filesystems. The working kernel image in /usr/src/linux/arch/i386/boot is called bzImage .

The idea is that if there is a functioning bzImage , it is possible to use that for the new floppy. Another alternative, which may or may not work better (it depends on the particular method in which you messed up your system) is discussed after the example.

First, boot from a boot/root disk combo or rescue disk, and mount the filesystem which contains the working kernel image:

mkdir /mnt mount -t ext2 /dev/hda3 /mnt

If mkdir tells you that the directory already exists, just ignore it. Now, cd to the place where the working kernel image was. Note that /mnt + /usr/src/linux/arch/i386/boot - /usr = /mnt/src/linux/arch/i386/boot Place a formatted disk in drive ``A:'' (not your boot or root disk!), dump the image to the disk, and configure it for your root filesystem:

cd /mnt/src/linux/arch/i386/boot dd if=bzImage of=/dev/fd0 rdev /dev/fd0 /dev/hda1

cd to / and unmount the normal /usr filesystem:

cd / umount /mnt

You should now be able to reboot your system as normal from this floppy. Don't forget to run lilo (or whatever it was that you did wrong) after the reboot!

As mentioned above, there is another common alternative. If you happened to have a working kernel image in / ( /vmlinuz for example), you can use that for a boot disk. Supposing all of the above conditions, and that my kernel image is /vmlinuz , just make these alterations to the example above: change /dev/hda3 to /dev/hda1 (the / filesystem), /mnt/src/linux to /mnt , and if=bzImage to if=vmlinuz . The note explaining how to derive /mnt/src/linux may be ignored.

Using LILO with big drives (more than 1024 cylinders) can cause problems. See the LILO mini-HOWTO or documentation for help on that.

19.17. It says `warning: bdflush not running'

This can be a severe problem. Starting with a kernel release after Linux v1.0 (around 20 Apr 1994), a program called ` update ' which periodically flushes out the filesystem buffers, was upgraded/replaced. Get the sources to ` bdflush ' (you should find it where you got your kernel source), and install it (you probably want to run your system under the old kernel while doing this). It installs itself as ` update ' and after a reboot, the new kernel should no longer complain.

19.18. I can't get my IDE/ATAPI CD-ROM drive to work

Strangely enough, lot of people cannot get their ATAPI drives working, probably because there are a number of things that can go wrong.

If your CD-ROM drive is the only device on a particular IDE interface, it must be jumpered as ``master'' or ``single.'' Supposedly, this is the most common error.

Creative Labs (for one) has put IDE interfaces on their sound cards now. However, this leads to the interesting problem that while some people only have one interface to being with, many have two IDE interfaces built-in to their motherboards (at IRQ15, usually), so a common practice is to make the soundblaster interface a third IDE port (IRQ11, or so I'm told).

This causes problems with older Linux versions like 1.3 and below. in that versions Linux don't support a third IDE interface. To get around this, you have a few choices.

If you have a second IDE port already, chances are that you are not using it or it doesn't already have two devices on it. Take the ATAPI drive off the sound card and put it on the second interface. You can then disable the sound card's interface, which saves an IRQ anyway.

If you don't have a second interface, jumper the sound card's interface (not the sound card's sound part) as IRQ15, the second interface. It should work.

19.19. It says weird things about obsolete routing requests

Get new versions of the route program and any other programs which do route manipulation. /usr/include/linux/route.h (which is actually a file in /usr/src/linux ) has changed.

19.20. ``Not a compressed kernel Image file''

Don't use the vmlinux file created in /usr/src/linux as your boot image; [..]/arch/i386/boot/bzImage is the right one.

19.21. Problems with console terminal after upgrade to Linux v1.3.x

Change the word dumb to linux in the console termcap entry in /etc/termcap . You may also have to make a terminfo entry.

19.22. Can't seem to compile things after kernel upgrade

The linux kernel source includes a number of include files (the things that end with .h ) which are referenced by the standard ones in /usr/include . They are typically referenced like this (where xyzzy.h would be something in /usr/include/linux ): #include <linux/xyzzy.h> Normally, there is a link called linux in /usr/include to the include/linux directory of your kernel source ( /usr/src/linux/include/linux in the typical system). If this link is not there, or points to the wrong place, most things will not compile at all. If you decided that the kernel source was taking too much room on the disk and deleted it, this will obviously be a problem. Another way it might go wrong is with file permissions; if your root has a umask which doesn't allow other users to see its files by default, and you extracted the kernel source without the p (preserve filemodes) option, those users also won't be able to use the C compiler. Although you could use the chmod command to fix this, it is probably easier to re-extract the include files. You can do this the same way you did the whole source at the beginning, only with an additional argument:

blah# tar zxvpf linux.x.y.z.tar.gz linux/include Note: `` make config '' will recreate the /usr/src/linux link if it isn't there.

19.23. Increasing limits

The following few example commands may be helpful to those wondering how to increase certain soft limits imposed by the kernel:

echo 4096 > /proc/sys/kernel/file-max echo 12288 > /proc/sys/kernel/inode-max echo 300 400 500 > /proc/sys/vm/freepages

19.24. Where To Report Bugs?

See 'Quick Steps - Kernel Compile' in the Section 2.8 .