$Id: README,v 1.61 2003/05/05 18:04:31 srivasta Exp $ This is the Debian GNU/Linux prepackaged version of the Linux kernel. Linux was written by Linus Torvalds and others. This package was put together by Herbert Xu Linux is copyrighted by Linus Torvalds and others. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 dated June, 1991. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA On Debian GNU/Linux systems, the complete text of the GNU General Public License can be found in `/usr/share/common-licenses/GPL'. INSTALLATION NOTES: Before you go any further, please allow me to point out that you need to have a few other packages installed before you can compile your own kernels (it is difficult to compile anything without a compiler ;-). Firstly, you will need gcc, the libc development package (libc5-dev or libc6-dev at the time of writing), and, on Intel platforms, bin86. [If you use the menuconfig target of make, you will need ncursesX.X-dev, and make xconfig also requires tkX.X-dev, and other packages these depend on] The packages suggested are: devel: gcc, libc5-dev/libc6-dev, binutils, make, and, for intel x86 platforms, bin86 (non-Intel platforms don't need this). interpreters: awk, which is contained in either the mawk or gawk packages base: gzip, shellutils, and grep. Some of these packages are marked essential, and hence are going to be present on your machine already. Others you have to check and install. Also, please note that some versions of gcc do not interact well with the kernel sources (gcc 2.95 has problems compiling the kernel without the flag '-fno-strict-aliasing'. This issue has been taken care of for recent kernels (2.2 and 2.4 series are fine) (I think you may have to edit the makefile for older kernels, or something). You may control which version of gcc used in kernel compilation by setting the environment variables CC and HOSTCC (please see the top level kernel Makefile). Of course, pretty GUI front ends to kernel configuration require more packages, but they are not strictly essential (though quite nice really). Oh, and of course, make-kpkg is part of kernel-package, usually found in section misc. For the Brave and the impatient: (Look for Kent's 10-Step Procedure to Compiling a Debian Kernel near the tail end of this file for more detailed HOWTO) Phase ONE: Getting and configuring the kernel 1% cd 2% make config # or make menuconfig or make xconfig and configure Phase TWO: Create a portable kernel image .deb file 3% make-kpkg clean 4% $Get_Root make-kpkg --revision=custom.1.0 kernel_image (Get_Root is whatever you need to become root -- fakeroot or sudo are examples that come to mind). NOTE: if you have instructed your boot loader to expect initrd kernels (which is the norm for recent official kernel image packages) you need to addd --initrd to the line above, and make sure that you have applied the cramfs initrd patch to the kernel sources (or modified mkinitrd config not to create a cramfs initrd). The cramfs initrd patch is shipped with Debian kernel sources. % $Get_Root make-kpkg --initrd --revision=custom.1.0 kernel_image Personally, I prefer non initrd images for my personal machines, since then adding third party modules to the machine has fewere gotchas Phase THREE: Install the kernel image on one or more machines 5# dpkg -i ../kernel-image-X.XXX_1.0_.deb 6# shutdown -r now # If and only if LILO/SILO/QUIK/PALO/VMELILO/ZIPL/yaboot/.. # worked or you have a means of # booting the new kernel. YOU HAVE BEEN WARNED!! With the addition of fakeroot ( a really nice program, I recommend it). Steps 1 to 4 can be carried out as a non root user. Step 5 does require root privileges. If you're using the patch_the_kernel facility, you may want to remove step 2 and instead insert `--config=menuconfig' into the make-kpkg command-line of step 4 (or perhaps use `xconfig' or `config' in place of `menuconfig'). This way, patching the kernel happens before menuconfig (or whichever), and you'll get better defaults for any questions introduced by the patches. (Also look at the --added_patches command line option to selectively apply some patches in conjunction with patch_the_kernel) Getting the kernel source ------- --- ------ ------ You can get kerel sources in several different ways: by installing a prepackaged Debian kernel source package (at the time of writing, it is kernel-source-2.4.20_2.4.20-6_all.deb). This shall create a file /usr/src/kernel-source-2.4.20.tar.bz2, which can be unpacked wherever you wish. Alternately, you can get linux-2.4.20.tar.bz2 from you favourite ftp.kernel.org mirror, (/pub/linux/kernel/v2.4/ in the ftp site). Unpacking kernel sources: ------------------------- Some of the suggestions about where to unpack the kernel packages are a) /tmp/linux b) /var/tmp/linux c) /usr/local/src/ d) /usr/src/linux-X.X.XX; where X.X.XX is the version number of the kernel. In any case, choose a partition that has a large amount of free space, since recent kernels, unpacked, run to about 23MB, and you need more than double that in order to create kernel-image, kernel-source, and the tar file (that is, if you choose to build everything together with the dist target in debian.rules -- say if you want, for whatever reason, to run dchanges on the files created). I needed nearly 60MB to create the full spectrum of packages for version 1.99.7 (and doubtless this size will go up in the future) [It has. Now even an gzipped kernel source is over 23MB]. [ EXAMPLE So, suppose you have chosen /usr/local/src/kernel as the place to build kernels. % cd /usr/local/src/kernel # or cd /path/to/where-ever/you/have/space % tar jvvfx /usr/src/kernel-source-2.4.20.tar.bz2 (or, tar jvvfx /path/to/download/linux-2.4.20.tar.bz2) ] Now, cd linux (wherever you have created the kernel sources). Configuration File ------------- ---- Kernel package by itself does not create any configuration file (.config); it uses whatever you have. You can use the previous version made for you machine by copying it over from /boot/config-Y.Y.YY, like so: % cp /boot/config-Y.Y.YY .config where Y.Y.YY stands for the old version of the kernel that you had hand tuned. If you do not wish to copy the old copy over, you can create a new one from scratch using make menuconfig (please look at the kenrel documentaion for help on configuring your kernel). Versions and revisions ---------------------- The version number is deduced from the kernel Makefile directly to ensure that the version numbers are in sync[1], so you don't have to worry about that. Then, remember to change the revision number (using the --revision option of make-kpkg). It has been suggested that you renumber the revision number in such a way that a generic kernel image package will not override the custom package while using dselect (or dpkg -BOGiE). You may also do this on the fly by setting the DEBIAN_REVISION environmental variable. The revision number (the argument supplied after the --revision flag) has certain constraints: a) It only has an effect during the configure phase (in other words, if a file called stamp-configure exists, this option has no effect -- run make-kpkg clean or manually remove stamp-configure, stamp-debian, and debian/official for it to have an effect -- I strongly suggest make-kpkg clean unless you know what you are doing). Additionally, official source package maintainers provide their own version numbers and data for the official uploads, and hence a number of things, including the Debian revision, is not modified by make-kpkg. If you happen to have an official source, (that would mean that the file debian/official exists), and want to use your own revision number, make sure you remove debian/official before running make-kpkg clean for this option to have an effect. So, if you want to re-run make-kpkg with a different revision number, you have to make sure you start with a clean slate. b) It may contain only alphanumerics and the characters + . (full stop, and plus) and should contain a digit. NOTE: No hyphens allowed (Look at the Debian Policy manual for details). Optionally, you may prepend the revision with a digit followed by a colon (:); this shall put your revision into a new epoch; more on this later. You should _not_ use a "_" in the revision number! As tempting as it may seem, it actually interferes with the policy. The revision number is required because dpkg imposes an ordering on version numbers, so that it can tell whether packages are being up- or downgraded and so that dselect can tell whether a package it finds available is newer than the one installed on the system. Dselect uses an option that prevents a package from being downgraded, for example. Packaged kernel-images in the distribution also have a version number - not at all coincidentally coinciding with the kernel version, because it is used to reflect the upstream version number. Note that the kernel version is also part of the package's name, thus it appears twice in the package's file name. It also gets a debian revision number relating to differences in builds. It then looks like: kernel-image-2.0.29_2.0.29-8.deb I've found that using a two-level scheme where the major level starts with a letter nicely does the job -- unless epochs are used, (--revision custom.Y, so the image package become kernel-image-X.X.XX-custom.Y.deb), and dselect and dpkg -BOGiE will refuse to downgrade to a generic kernel (don't give the BOG arguments to dpkg if you actually do want to downgrade later). The reason for telling kernel-package that the package has a version "custom-x.y.whatever.you-want.to+add.more-just.do.not+use.an=underscore" is that to dpkg that is always a higher version number than any version number starting with a numeral ( e.g. "a" > "2" like "b" > "a". ) This way, dselect will not try to upgrade your "roll-it-yourself" kernel-image when a new build of the distribution default kernel appears in the archive. Unfortunately, this fails if the upstream maintainer uses epochs to correct a version misnumbering ;-(. The good news is that you can add your own epoch to your customized image, ugly though that may be. (--revision 1:custom.Y; the kernel image file shall remain kernel-image-X.X.XX-custom.Y.deb, but dpkg shall know that it should not replace that with a standard kernel with an epoch. Hopefully, we shall never see an epoch greater than 1 on a standard kernel, but who knows. Choose your epoch, if you must use it, wisely. I fear, though, that with the introduction of epochs in kernel image versions shame has entered the garden of eden, and we must forever use epochs to guard against forced upgrades. So, try using an epoch for your custom packages: make-kpkg clean $Get_Root make-kpkg --revision=3:custom.1.0 kernel_image (Get_Root is whatever you need to become root -- fakeroot or sudo are examples that come to mind). And the next time when you build a kernel, because you just bought a new sound card or you discovered that you suddenly want masquerading in your kernel enabled, you'll type: make-kpkg clean $Get_Root make-kpkg --revision=3:custom.2.0 kernel_image (Get_Root is whatever you need to become root -- fakeroot or sudo are examples that come to mind). (remember to do a make-kpkg clean before you compile again with a different revision, or else the revision flag shall not have any effect) NOTE about using initial ram disk images (initrd). Recent official kitchen sink kernel image packages tend to use this, in order to accomodate as wide a vareity of root file system types as humanly possible without building them all into the kernel. In order to use these images, you need to instruct you boot loader that this is a kernel image using intrd, and tell the boot loader where to find the initrd image. Unfortunately, you can't just substitute a non initrd image afterwards without changing the boot loader instructions. Additionally, the mkinitrd program in Debian creatre a cramfs initrd, and you need an additional cramfs initrd patch in the kernel to be able to load the initrd. This patch is shipped with official debian kernel sources. So, you must apply the patch, or configure mkintrd to use another file system. like ext2. So, if your boot loader configuration expects to see an initrd image, add --initrd to the above invocation, like so: make-kpkg clean $Get_Root make-kpkg --initrd --revision=3:custom.2.0 kernel_image When make-kpkg is finished, you'll have kernel-image-2.0.29_custom.1.0_i386.deb and all it takes now is to install the package (as root): # dpkg -i kernel-image-2.0.29_custom.1.0_i386.deb This will install the kernel, the modules, the map file and do some other administrativia and finally it will ask you if you want to make a boot floppy and if you want to run lilo now. Now, there is a caveat: If you already have kernel 2.0.29 installed, and you have a freshly created custom 2.0.29 kernel [having remembered to do a make-kpkg clean in between ;-], just installing the new 2.0.29 kernel shall install modules (as it should) in /lib/modules/2.0.29, which is where the old modules were! If you have added or removed modules relative to the old 2.0.29 kernel (very likely if your old kernel was the default gigantic generic kernel), then you shall have a mish-mash of modules in /lib/modules/2.0.29 ;-( Unfortunately, there is no reasonable solution; I suggest moving the old modules directory before installation, like so (need to be root): # mv /lib/modules/2.0.29 /lib/modules/2.0.29.save # dpkg -i kernel-image-2.0.29_custom.1.0_i386.deb and later get rid of the .save directory. People who want to have multiple flavours of the same kernel version around should look at the append_to_version flag of make-kpkg. This appends to the EXTRAVERSION variable of the kernel Makefile, and does not require one to edit that makefile manually. This can also be done by setting the environment variable APPEND_TO_VERSION. The command line invocation overrides the env variable. The method described in the /usr/share/doc/kernel-package/Flavours.gz file is obsolete (Note: This involves modifying the kernel sources top level Makefile). Also, if recompiling and using a different flavour, one needs to do a make-kpkg clean in between compiles. You may also place long term directives (like your name and email address) in the file /etc/kernel-pkg.conf (or ~/.kernel-pkg.conf). Putting your name and address in that file is a good idea, to remind you that this is not an official package, unless, of course, you happen to be the maintainer (Hi Herbert). The file /etc/kernel-pkg.conf (or ~/.kernel-pkg.conf) is actually a Makefile snippet included during the kernel packages build process, and hence you may put any legal Makefile directive in that file (just make very sure you know what you are doing ;-). At the moment, the user modifiable variables supported are: maintainer Local kernel-* package maintainer. Please note that any apostrophes "'" shall have to be quoted like so: maintainer = John O'\\''Brien. Yes, this is ugly, but this works. email The email address of that person. pgp Name to search for in the pgp database _iff_ separate modules (like pcmcia etc) are being built in $(MODULE_LOC:-/usr/src/modules)/*. Can be set from environment variable PGP_SIGNATURE. Defaults to maintainer. debian The Debian revision of the kernel packages. Can be set from the environment variable DEBIAN_REVISION. Defaults to 1.0. link_in_boot Set to True if you want the kernel image symlink (vmlinuz) in /boot rather than the default /. Can be set from the environment variable LINK_IN_BOOT. Defaults to undefined. kimage The kernel image type (i.e. zImage or bzImage). Can be set from the environment variable IMAGE_TYPE. Defaults to bzImage. no_symlinks Mutually exclusive to reverse_symlinks Can be used with link_in_boot. The image is placed in vmlinuz (instead of /boot/vmlinuz-X.X.XX). The old vmlinuz is moved to vmlinuz.old unconditionally. (Normally, that is only done if the version of the new image differs from the old one). This restricts you to two images, unless you take additional action and save copies of older images. This is for people who have /boot on a system that does not use symlinks (and say, they use loadlin) This is a Hack. reverse_symlinks exclusive to no_symlinks. Can be used with link_in_boot. Just like no_symlinks, except that the /boot/vmlinuz-X.XX is symlinked to the real new image, vmlinuz. This too restricts you to just two images unless further action is taken. The older symlinks are left dangling. This is for people with /boot on umsdos, and who can't see the link in dos, but do want to know the image version when in Linux. This is a Hack. image_dest If you want the symbolic link (or image, if move_image is set) to be stored elsewhere than / set this variable to the dir where you want the symbolic link. Please note that this is not a boolean variable. This may be of help to loadlin users, who may set both this and move_image. Defaults to /. This can be used in conjunction with all above options except link_in_boot, which would not make sense. (If both image_dest and link_in_boot are set, link_in_boot overrides). patch_the_kernel This is an experts only variable. If set to YES (ENV variable PATCH_THE_KERNEL overrides this), the build process causes run-parts to be run over /usr/src/kernel-patches/$(architecture)/apply and (hopefully) reverses the process during clean by running run-parts over /usr/src/kernel-patches/$(architecture)/unpatch. The special architecture all is used for arch independent patches. You may use the --added_patches command line in conjunction with this variable to selectively apply only some patches from that directory. The people who package the pacthes should have arranged to have the order of application and unapplication be sane. This variable is automatically set to YES if you use the option --added-patches. root_cmd This should be set to a means of gaining superuser access (for example, `sudo' or `fakeroot') as needed by dpkg-buildpackages' -r option. This is used to call dpkg-buildpackage with the proper options. The environment variable ROOT_CMD overrides this. do_clean Set to anything but YES, this shall forego the make clean done in the kernel source tree after building the kernel image package. The environment variable CLEAN_SOURCE overrides this. install_vmlinux Set to YES to install the uncompressed kernel ELF image along with the bootable compressed kernel image (vmlinuz). This image is necessary for profiling kernel and userspace with oprofile (oprofile.sourceforge.net, i386 only). make_libc_headers This is meant to be used by the libc6 maintainer, when he compiles libc6, to also package up the corresponding headers. DO NOT SET THIS as a mismatch between the headers you package and libc6 may well create a subtle instability in all code compiled on your machine. You have been warned. The environment variable MAKE_LIBC_HEADERS overrides this. The value of a variable can be set so: a) Defaults exist in the rules file. These are the values used if no customization is done. b) Variables can be set in the config file /etc/kernel-pkg.conf (or ~/.kernel-pkg.conf). These values override the defaults. c) Variables can also be set by setting a corresponding environment variable. These values override the config file and the defaults. d) Using make-kpkg options, or, if using the rules file directly, on command line ( # xxx/rules DEBIAN_REVISION=2.0a kernel_image). This overrides all the above methods. Please see kernel-pkg.conf (5). However, most of these are done on the machine you compile on: but you may need to install generic kernel image packages from time to time, and you need control over where the image sticks the symbolic links and such. With this in mind, there is the configuration file /etc/kernel-img.conf which sits on the target machine (the machine that the dpkg -i is run on, which need not be the same machine the kernel was compiled on), and that allows you to tweak these variables: This file is automatically created by the installation script if it does not exist, and neither does the symbolic link /vmlinuz. The script asks the user whether the symbolic link should be created, and stashes the answer into /etc/kernel-img.conf no_symlinks Mutually exclusive to reverse_symlinks Can be used with link_in_boot. The image is placed in vmlinuz (instead of /boot/vmlinuz-X.X.XX). The old vmlinuz is moved to vmlinuz.old unconditionally. (Normally, that is only done if the version of the new image differs from the old one). This restricts you to two images, unless you take additional action and save copies of older images. This is for people who have /boot on a system that does not use symlinks (and say, they use loadlin) This is a Hack. reverse_symlinks exclusive to no_symlinks. Can be used with link_in_boot. Just like no_symlinks, except that the /boot/vmlinuz-X.XX is symlinked to the real new image, vmlinuz. This too restricts you to just two images unless further action is taken. The older symlinks are left dangling. This is for people with /boot on umsdos, and who can't see the link in dos, but do want to know the image version when in Linux. This is a Hack. do_symlinks default, the kernel image post installation script shall create or update the /vmlinuz and /vmlinuz.old symbolic links. This is true if a /vmlinuz link already exists, however, in absence of /vmlinuz, the script looks to see if this configuration file exists. If it does not, the configuration script asks the user whether to create the symbolic link, and stashes the answer in a newly created /etc/kernel-img.conf. If the configuration file already exists, and if this option is set to no, no symbolic link is ever created. This for people who have other means of booting their machines, and do not like the symbolic links cluttering up their / directory. link_in_boot Set to True if you want the kernel image symlink (vmlinuz) in /boot rather than the default /. Defaults to undefined. image_dest If you want the symbolic link (or image, if move_image is set) to be stored elsewhere than / set this variable to the dir where you want the symbolic link. Please note that this is not a Boolean variable. This may be of help to loadlin users, who may set both this and move_image. Defaults to /. This can be used in conjunction with all above options except link_in_boot, which would not make sense. (If both image_dest and link_in_boot are set, link_in_boot overrides). move_image Instead of creating symbolic links to (or, if reverse_symlinks is set, from) image_dest, the image is moved from its location in /boot into image_dest. If reverse_symlinks is set, /boot shall contain a symbolic link to the actual image. This option can be useful to people using loadlin, who may need the image to be moved to a different dos partition. This variable is unset by default. clobber_modules If set, the preinst shall silently try to move /lib/modules/version out of the way if it is the same version as the image being installed. Use at your own risk. This variable is unset by default. do_boot_enable If set to NO, this shortcircuits all attempts to create boot floppies, run lilo, etc. This has the additional side effect that the postinst is silent. Setting both do_bootfloppy and do_bootloader to NO implies setting do_boot_enable to NO. Defaults to Yes. do_bootfloppy If set to NO, this prevents the postinst from asking questions about creating a boot floppy, and no boot floppy is created. The bootloader shall still be run. This may cut down on the interaction the postinst has. (It still prompts before formatting /dev/fd0). Defaults to Yes. do_bootloader If set to NO, this prevents the postinst from running the bootloader. The user may still be asked to create a floppy, unless do_bootfloppy is also set to NO. Defaults to Yes. postinst_hook Set this variable to a script to be executed during installation after all the symbolic links are cre- ated, but before running the bootloader or offer- ing to create a floppy. This script shall be called with two arguments, the first being the version of the kernel image, and the second argument being the location of the kernel image itself. Errors in the script shall produce a warning message, but shall be otherwise ignored. An example script for grub users is present in /usr/share/doc/kernel-package/ directory. postrm_hook Set this variable to a script to be executed in the postrm (that is, after the image has been removed) after all the remove actions have been performed. This script shall be called with two arguments, the first being the version of the kernel image, and the second argument being the location of the ker- nel image itself. Errors in the script shall pro- duce a warning message, but shall be otherwise ignored. Please see kernel-img.conf (5). To generate a new kernel image, just run % make-kpkg clean % $Get_Root make-kpkg --revision=custom.1.0 kernel_image (Get_Root is whatever you need to become root -- fakeroot or sudo are examples that come to mind) or (if you use initrd) $Get_Root make-kpkg --initrd --revision=3:custom.2.0 kernel_image This will create a default kernel image (as in the image package or available on the boot disks. The kernel image package produced, on installation, shall offer you a chance to create a boot disk, or to run LILO (or SILO, QUIK, VMELILO, ZIPL, yaboot, PALO, or update the grub menu), but the default is not to do either, and you may choose to ignore these friendly overtures by the postinst. If you want a custom kernel, you may generate a config file by any of these methods (just follow the directions). % make config # boring old tty based method or % make menuconfig # curses based menu driven method (uses color if you have any) % make xconfig # An X window system based method -- make sure you are running X windows when you call this. All these methods ultimately generate a .config file. If you already have a .config file, just copy it to this directory, and you are go. With a custom .config file in place (created as above) run again: % make-kpkg clean % $Get_Root make-kpkg --revision=custom.1.0 kernel_image (Get_Root is whatever you need to become root -- fakeroot or sudo are examples that come to mind) $Get_Root make-kpkg --initrd --revision=3:custom.2.0 kernel_image |-----------------------------------------------------------------------| | Special needs | | Or, for people who want to minimize time spent in fakeroot (for | | whatever reasons that maybe -- I think that the separate step as | | non-fake-root is not required, but that is a personal opinion) | | % make-kpkg clean | | % make-kpkg --revision=custom.1.0 build | | % $Get_Root make-kpkg --revision=custom.1.0 kernel_image | | (Get_Root is whatever you need to become root -- fakeroot or | | sudo are examples that come to mind) | | | | For people who wish to see the username (not root) when they do a | | uname -a on the machine when they install the kernel, there is a | | trick: | | % make config | | % make-kpkg build | | % $Get_Root make -f debian/rules kernel-image-deb | | shall generate a kernel image with the username of the user embedded | | in it. | | | | If you use initrd images (and have told your boot loader so) you need | | to include the --initrd option on the command line, like so | | | | % $Get_Root make-kpkg --initrd --revision=3:custom.2.0 kernel_image | | | ------------------------------------------------------------------------- To create a source or header package, run % make-kpkg clean % $Get_Root make-kpkg --revision=custom.1.0 kernel_source % $Get_Root make-kpkg --revision=custom.1.0 kernel_headers Note: You only need one of these. (Get_Root is whatever you need to become root -- fakeroot or sudo are examples that come to mind). Similarly, the documentation package is built by: % $Get_Root make-kpkg --revision=custom.1.0 kernel_doc Or if you want to generate the whole package, % $Get_Root make-kpkg --revision=custom.1.0 \ --pgpsign="Your pgp ID" buildpackage Note that this needs a pgp key. (Get_Root is whatever you need to become root -- fakeroot or sudo are examples that come to mind). A note on boot loaders: the kernel-image install-scripts arrange to have /vmlinuz and /vmlinuz.old point to the latest kernel image and the next most recent one, respectively. You may choose to have your boot loader take advantage of this by putting image = /vmlinuz and image = /vmlinuz.old lines in your lilo.conf (or whatever config files your boot loader uses -- please read documentation on your boot loader for details). Oh, and if your kernel image package uses initrd (as do the newer official kernel image packages), please do not forget to add a line (initrd=/boot/initrd-2.4.X-flavour) in your lilo.conf file pointing out this fact to your boot loader. Conversely, people who wish to tightly control the versions in lilo.conf (believe me, people, this gets to be a pain in the neck fast) can use image = /boot/vmlinuz-X.X.XX. For folks using grub, there are now postinst_hook and postrm_hook variables that can be pointed to scripts that add or remove a line from the grub menu list at kernel image install and remove times. A sample script to add lines to a grub menu file is included in the dir /usr/share/doc/kernel-package/; and simple scripts like: # perl -nle 'print unless /^#Autogenerated by kernel-image $version/ \ .. /^#End kernel-image '$version/' or for awk fans # awk 'BEGIN{printit=1} /^#Autogenerated by kernel-image $version/{printit=0} /^#End kernel-image '$version/{printit=1} {if (printit) {print}}'. or # awk '{p=0} /^#Autogenerated by kernel-image $version$/, /^#End kernel-image '$version$/ {p=1} {if(!p) print}' < foo can be put in a script and added to the postrm hook script to remove the lines added by kernel_grub_conf.sh So that loadlin people don't feel left out, all this talk about LILO does not mean to ignore loadlin, you can use the generated kernel-image just as easily (simply ignore the fol-de-rol with symlinks in /). For instance, you could: [1]# dpkg -BRGiE kernel-image-X.X.XX, # need to be root and then [2]% cp /boot/vmlinuz-X.X.XX [3]% echo '' > /boot/vmlinuz-X.X.XX So you don't have the image taking up space, but still leave a target for the /vmlinuz symlink. Recompiling a kernel image ----------- - ------ ----- It happens to all of us. When we configured the kernel, we missed out on an module. Or we added in more things than we really need, and need to compile again. If you just recompile a kernel image, it shall, when installed, contain the same /boot/{System.map,config,vmlinuz}-X.X.XX files and the /lib/modules/X.X.XX directory that the previous kernel image contained. If you try to install the recompiled kernel image over the previous kernel image (same version and flavour), then the install scripts detect that, and ask you to move at least the /lib/modules/X.X.XX dir away. If you continue anyway, the files in /boot shall be overwritten. Also, if you try to recompile with a changed --revison option or a different debian revision, you shall have to make-kpkg clean, and then recompile. Tecras and other notebooks -------------------------- (Many thanks to Philip Hands and Avery Pennarun for this explanation) Tecras and other notebooks, and some PCs have a problem where they fail to flush the cache when switching on the a20 gate (IIRC), which is provoked by bzImage kernels, but not by zImage kernels. bzImage files are actually "big zImage" not "bzipped Image". bzImage kernels can be as large as you like, but because they need to decompress into extended memory, they aggravate this problem. zImage kernels just compress into conventional memory, so they never need to touch the a20 gate, but they hit the 640k limit. There are two solutions that I know of: 1) Apply a patch, which flushes the cache. Unfortunately this causes other machines to crash so is not universally applicable (hence the tecra disks being segregated from the mainstream). 2) Build a zImage, rather than bzImage kernel. This seems to get round the problem. use the --zimage option to make-kpkg, or even set this as the default in /etc/kernel-pkg.conf (or ~/.kernel-pkg.conf). There some add-on modules that hook into make-kpkg and the kernel sources so that they may be kept in synchrony with the kernel you run. If you have such a module source package, for example, pcmcia-source, then please read README.modules as well. If you don't never mind. (The file is in /usr/share/doc/kernel-source-X.X.XX/. If you don't have kernel-source packages installed [that's OK], there is a copy in /usr/share/kernel-package/README.modules). Have fun, Manoj Srivastava Foot note 1: For an explanation on why this synchronization is required, consider this. The kernel knows what version it is, as given in the kernel Makefile as the variables VERSION, PATCHLEVEL, and SUBLEVEL. It will look for the modules in /lib/modules/$VERSION.$PATCHLEVEL.$SUBLEVEL. The Debian scripts think they know what the kernel version is, as given in the Debian file rules as the variable v (near the top). It then proceeds to put the modules in /lib/modules/$v. So, it is essential that the kernel (Makefile) and the Debian script (rules) agree about the version number, or the kernel will never figure out where the Debian scripts hid the modules. So change the version number in the file rules (v = X.X.XX) to be the same version as given in the kernel Makefile (this will be $VERSION.$PATCHLEVEL.$SUBLEVEL). -- Manoj Srivastava PGP Key ID: 1024/C7261095 Key fingerprint = CB D9 F4 12 68 07 E4 05 CC 2D 27 12 1D F5 E8 6E ====================================================================== Kent's 10-Step Procedure to Compiling a Debian Kernel Kent West (I may leave a step or two out, but this is the gist. This example uses the latest kernel version at the time of writing, which was 2.4.18) 1. Run "dselect". Choose "Update". Choose "Select". "space bar" to get out of the Help screens. Use "/" (without the quotes) to start search. Search for "kernel-source". Mark for installation the 2.4.18 or so. 1b. Use "/" to search for "kernel-package". Mark it for installation also. "Enter" to get back to the main dselect menu. 1c. Choose "Install". This will download a file in /usr/src with a .tgz extension, as well as install "kernel-package". 2. "cd /usr/local/src" 3. "bunzip2 /usr/src/kernel-source-2.4.18.tar.bz2" (or whatever the file is named). This will unzip (decompress) the file. 4. "tar -xvf kernel-source-2.4.18.tar". This will untar the file (x means extract, v means "be verbose", f means "use the file named ..."). A new subdirectory named kernel-source-2.4.18 will be created with all the untarred files under it. You can also do steps 3 and 4 in one tar command, but I never do; habit is the only reason. I think you just add the "j" switch to tar, such as "tar -xvjf 'filename'". (It used to be the I switch to tar, but they moved from I to j). Pause and Breathe. You now have the kernel sources installed. You haven't done anything with them yet, but they're installed. 5. "cd /usr/local/src/kernel-source-2.4.18" 6. "make menuconfig". This will start a curses-based (text-based) menu-driven application. There are a lot of choices here, and many of them won't make sense to you at all. Take the time to look at most all of them (some of them you'll know you don't need, like SCSI support if you have an all-IDE system, or Amateur Radio Support if you're not a ham) and read the HELP on them if they look relevant. A lot of the time the HELP will suggest whether you should include it or not, and generally when in doubt, leave things set the way they are. Some things to check out: * the correct processor for your system (AMD vs Pentium vs P4, etc) * Symmetric Multi-Processing; "No" if you only have a single processor * Loadable module support; "Yes" to all three sub-items. * Parallel port support; "Yes" if you have a parallel printer. "No" to keep things simple for now if you can live without the printer for a while. * Plug-N-Play; "Yes"; ISA P-N-P; only if you have any ISA cards installed. * Character devices; turn on Direct Rendering if your video card is listed, and turn on agpgart if your video chipset is listed; mice if you have a PS/2 mouse * Sound - find the driver for your card * Input core support (some USB stuff needs this, but I'm hazy on it - use your best guess) * USB support (make your best guesses; I'm hazy on it) * You probably won't need to touch the following: - General Setup - Memory Technology - Block devices - Multi-device support - Networking options - Telephony support - ATA/IDE/MFM/RLL support - Fusion MPT device support - I20 device support - Amateur Radio support - Infrared support - ISDN subsystem - Old CD-ROM drivers (unless you have a non-ATAPI CD-ROM drive for now; wait till you've compiled a kernel or two) - Multimedia devices (unless you have a tv tuner, etc; too complicated for now; wait) - File Systems (unless you'll be accessing a DOS/FAT/NTFS/etc partition, or Windows shares via smb, etc) - Console Drivers (play with different text modes at bootup) - kernel hacking It's by turning off unneeded stuff that the hackers get their kernels down in size and up in efficiency. But you're not really worried about either at this point. 6b. Exit and save your configuration. This will create a hidden file named ".config" in the "/usr/local/src/kenel-source-2.4.18" directory. You could edit this file directly to make changes to your configuration, but I wouldn't. All that this step (6 and 6b)) has done is to set up this configuration file. This file is read by the actual kernel compilation process to compile the options you've specified. Pause and breathe again. You have now configured your options for the next kernel compilation, but you have not yet compiled it. 7. Compile the kernel: use the command "make-kpkg clean; make-kpkg kernel_image". This will cause a bunch of grinding and text; depending on the speed of your computer and the options you chose, this could take minutes (fast computer) to hours (slow computer). This step is a Debian-way of compiling the kernel. The "other" way is to do it manually, which consists of several steps such as "make dep" and "make modules" and "make modules_install" and manually finding and moving the kernel to where it needs to be and setting up symlinks and configuring lilo.conf and running lilo. The Debian-way is much easier. The result will be a file named something like "kernel-image-2.4.18_1.00.Custom_i386.deb", one level up, in "/usr/local/src". You can try reading the documentation in the "kernel-package" package. A more complicated comman line to build your kernel image, with all kinds of bells and whistels, is: make-kpkg clean make-kpkg -rootcmd fakeroot --append-to-version -custom.${VER} \ --revision custom.${VER} kernel_image modules-image This one also builds any standalone modules packages you may have installed on your machine. Pause and breathe. You have now compiled your kernel and made a .deb file out of it for easy installation. If you're (re)compiling a kernel with the same version number as your current version, you'll probably want to run the command "mv /lib/modules/2.[whateverversion] /lib/modules/2.[whateverversion].old" to move the old modules out of the way in preparation for the creation of new modules. If you forget, then step 8 shall warn you that you need to do this before it overwrites the old modules, and you can just open a new terminal and do it then without canceling whichever step it concerns. This is only applicable when (re)compiling the same version number of kernel as your existing version. 8. Install the new .deb file. Use the command "dpkg -i /usr/local/src/kernel-image-2.14.18*.deb". This will install the new kernel to where it needs to be (and I believe configure /etc/lilo.conf if [and only if] /etc/lilo.conf does not exist) and run lilo. Pause and breathe. You are ready for a reboot to start running your new kernel. Make sure you have a backup method for getting into your box (a Debian install CD, or boot floppy, etc) in case something goes wrong. I generally have a lilo.conf file that includes at least one other image than /vmlinuz and /vmlinuz.old 9. Reboot. After the reboot, you should be running the new kernel. Typing "uname -a" will tell you what version of kernel you are running. Test the machine and see if things work properly. Pause, breathe, celebrate. You've successfully compiled and installed your first kernel! You may not have a working sound card or USB stuff yet, and other things may have broken, but now that you know the basic procedure you can go back and try again. 10: Celebrate. Have fun! Kent