+++ /dev/null
-Notes on Red Hat 5.2 kernel installation (See Addendum for RH6.1)
-=================================================================
-
-Warning: We (the FreeS/WAN Project http://www.xs4all.nl/~freeswan/)
-had nothing to do with designing the kernel installation process. This
-document explains some tricky points that we wish we had been told.
-We don't know if these notes apply to systems other than Red Hat 5.2.
-This is meant as a supplement to other kernel install guides (such as
-the Red Hat 5.2 Installation Guide section 11.6).
-
-Goal: install a new kernel on RH5.2 in such a way that it doesn't
-interfere with any other kernels. This should be repeatable: each new
-kernel should have this property. Each should remain bootable.
-
-Problem: there are several components to a kernel, and each must be
-segregated. How are the parts kept apart? How are they found?
-
-All the parts live in the file system, so it all comes down to
-pathnames. Well, except for the fiddly bits in /etc/lilo.conf. What
-are the parts?
-
- /lib/modules/VER/ directory for kernel modules
- /boot/vmlinux-VER the kernel
- /boot/System.map-VER the kernel symbol table
- /boot/initrd-VER.img the initial ramdisk (for modules needed
- at boot time -- usually not necessary)
- /boot/boot.b the second-stage loader
- /boot/map the map file, an index into system index for
- all files used by boot loader (all kernels,
- all initrds, perhaps /boot/boot.b, and itself)
-
-This list does not include /boot/module-info-VER. That is supplied
-by RedHat, and it isn't clear to me how to build it or why.
-
-In each entry, I've used "VER" to signify a version number. For
-RH-supplied kernels, these look like 2.0.36-0.7 (the original 5.2) or
-2.0.36-3 (the kernel updates).
-
-There are also symbolic links:
- /lib/modules/preferred created by /etc/rc.d/rc.sysinit
- /boot/System.map created by /etc/rc.d/rc.sysinit
- /boot/module-info created by /etc/rc.d/rc.sysinit
- /vmlinuz created by ???
-I don't know when the /vmlinuz symlink is set up and I don't know
-for what it is used.
-
-If you follow the RH procedures, documented in 11.6 of their Installation
-Guide, all your VERs will be 2.0.36. This is very bad: all your builds
-will step on each other. Worse, your new module directory will be half
-picked up when you boot a stock RH kernel binary!
-
-It is important to know how the various parts of the built kernel are
-found at booting.
-
-- the kernel path is specified in the image= option in lilo.conf.
- (Lilo.conf may specify several and one is selected at boot time
- by default or user selection.) The kernel is loaded by the
- boot loader.
-
-- The initial ramdisk is a per-image option (initrd=) specified in
- lilo.conf. (It isn't described in the RH5.2 lilo.conf(5) manpage!).
- The initial ramdisk is loaded into RAM by the boot loader.
-
-- Since the boot loader doesn't know about the file system, it needs a
- map to figure out which absolute disk blocks to load, and where.
- This is /boot/map. It is built by the lilo command (also known as
- the map installer). It will have indices for the all the kernels
- that can be booted, all their initial ram disks, perhaps
- /boot/boot.b, and itself. This is why moving the blocks of these
- files throws off the boot loader -- lilo must be rerun after even a
- cp command to one of them.
-
-- the modules directory is found two different ways. Unfortunately,
- they don't mesh properly:
-
- + at boot time, /etc/rc.d/rc.sysinit tries to figure out the correct
- subdirectory of /lib/modules, using the .rhkmvtag trick (see
- later). It then builds a symlink /lib/modules/preferred to
- record this. It also invokes depmod to build the module
- dependency info. At the same time, it creates the symlinks
- /boot/System.map and /boot/module-info, using the inferred
- value for VER!
-
- + modprobe and friends stupidly look first in /lib/modules/2.0.36
- (more precisely, /lib/modules/`uname -r`) and then in
- /lib/modules/preferred. So if there is a /lib/modules/2.0.36 and
- it is the wrong one, you are in trouble.
-
- If there is no /lib/modules/2.0.36, then both searches above will
- agree (a very Good Thing). So I recommend strongly that you not
- have a /lib/boot/2.0.36 at boot time. Unfortunately, you will get
- one during the kernel install process. Be sure to rename it. I
- suggest using 2.0.36-x (for some unique x) as VER.
-
-- Red Hat supplied /lib/modules/VER directories contain a hidden file
- .rhkmvtag. This file contains exactly one line. This line is
- exactly the same as the contents of /proc/version while the
- corresponding kernel is running. For the stock kernel, the line is:
-Linux version 2.0.36 (root@porky.redhat.com) (gcc version 2.7.2.3) #1 Tue Dec 29 13:11:13 EST 1998
-
-- At boot time, /etc/rc.d/rc.sysinit uses the .rhkmvtag files to
- figure out which of the /lib/modules/* directories matches the
- kernel. If it could figure out the directory, it uses this
- information to set the symlinks mentioned above. It then runs
- depmod to build the module dependency information (in
- /lib/modules/preferred/modules.dep, if it created the
- /lib/modules/preferred symlink). I recommend looking at the code.
-
-- The documented kernel install procedures DO NOT fill in the
- .rhkmvtag file for the new modules directory! So you should do so
- by hand. You have to figure out what the contents should be. Here
- is is a command that will do the job, assuming that
- /usr/src/linux/vmlinux is the kernel associated with
- /lib/modules/2.0.36/:
-
- strings /usr/src/linux/vmlinux \
- | grep 'x version' >/lib/modules/2.0.36/.rhkmvtag
-
-I've recommended (above) that you use 2.0.36-x for VER when you install
-a kernel. What should x be? I have found that there is a hidden file
-/usr/src/linux/.version which contains a counter that gets incremented
-whenever you do a "make install" in the kernel (see target
-newversion). There are some other times that it gets incremented, but
-I think that it all works out. It also gets incorporated into the
-resulting kernel's /proc/version, prefixed with ``#''. This makes it
-a natural.
-
-Here is a script to do the recommended renaming:
-
- # VER will eventually need to be updated
- VER=2.0.36
- VERX=${VER}-`cat /usr/src/linux/.version`
-
- strings /usr/src/linux/vmlinux | grep 'x version' >/lib/modules/$VER/.rhkmvtag
- mv /lib/modules/$VER /lib/modules/$VERX
- mv /boot/System.map-$VER /boot/System.map-$VERX
- mv /boot/vmlinuz-$VER /boot/vmlinuz-$VERX
-
-And, if an initrd has been built (usually it is best to arrange not to
-use one -- see the Red Hat Installation Guide):
-
- /sbin/mkinitrd /boot/initrd-$VERX.img $VERX
-
-Remember: a new lilo.conf entry is needed for the new kernel, and then
-the lilo command will need to be rerun.
-
-Now that kernel installs don't overwrite the results of previous ones,
-you will need to manually delete the components and their lilo entry
-to get rid of them.
-
-Please send comments, additions, and corrections to:
-
-Hugh Redelmeier
-hugh@mimosa.com voice: +1 416 482-8253
-
-
-Addendum: Red Hat 6.1
-=====================
-
-The kernel supplied with RH6.1 kernel is out of date, so you might
-wish to use a newer one.
-
-Much of the description for 5.2 still applies, but the procedure is
-quite different because the .version file is no longer used. Instead,
-the top-level Makefile contains a definition EXTRAVERSION which adds a
-qualifier to the version for most purposes. No manual renaming is
-required.
-
-Before building the kernel, change EXTRAVERSION by editing
-/usr/src/linux/Makefile, and make an appropriate entry in /etc/lilo.conf.
-
-EXTRAVERSION is a feature of the standard kernel sources, not just the
-ones supplied by Red Hat.
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