Installing/Upgrading/Building the Kernel

Installing/Upgrading the Kernel

14-Oct-2001
Stefan Jeglinski

original R4 page
installing/upgrading a prebuilt kernel
getting the LinuxPPC kernel source code
building a new kernel
return to the home page

installing/upgrading a prebuilt kernel

Download a gzipped kernel (likely to have the name vmlinux-*.gz) from whereever you can find it. The * may be a version number or some other descriptor. The linuxppc.org site or its mirrors are your best place to start. The links and mirrors and their directories used to change at whim from time to time, but seem a bit more stable these days. I can make my kernels available on request.
If you're on a roll and find the kernel, download the compiled modules and System.map as well (likely to have the names modules-*.tar.gz and System.map-*.gz, respectively).
Unpack the kernel: gunzip vmlinux-*.gz. For the OldWorld Open Firmware method of booting, the target directory for the kernel is /boot, which may already have other vmlinux kernels in it. The accepted practice when there are multiple kernels is to name each one according to its version number (vmlinux-*) and create a symbolic link to the one that will be active for the boot: ln -s vmlinux-* vmlinux. If BootX is being used, the vmlinux kernel must be copied to the MacOS boot volume in binary form and placed in the Linux Kernels folder in the System Folder. In this case, there is no need for any kernel in the /boot directory; however, it is recommended that one be there anyway as a secondary boot strategy if there are problems using BootX.
Unpack the modules: tar xzvf modules-*.tar.gz. It shouldn't matter, but this might be best done from the / directory. It creates the /lib/modules/* directory and places the necessary files in them. You may note that you already have directories in /lib/modules/ from the install or other kernel builds.
Unpack the System.map: gunzip System.map-*.gz. The target directory for System.map-* is /boot, which may already have other System.map files in it. The accepted practice when there are multiple System.map files is to name each one according to its version number and create a symbolic link to the one that will be active for the boot: ln -s System.map-* System.map
Reboot the system from the console using shutdown -r. If BootX is being used and the kernel already resides on the MacOS boot volume, the BootX splash screen will be displayed by the MacOS, and the correct kernel can be selected. For most users' configurations, the MacOS will have to be booted once to put the kernel in the correct place before Linux can be rebooted with the new kernel.

getting the Linux kernel source code - 3 basic methods

Option One. Find and download the latest kernel tree for PPC via rsync. (rsync binary must be installed). Trees may go dormant or extinct with time and other trees may be created; the linuxppc-user list is the best source of current info. Do not assume that different repositories have the same code, even though they may refer to the same tree. The basic command sequence to use is
- figure out which sites have which trees with rsync rsync://the_site
- sites to try include:
- pick a tree and create a /usr/src/the_tree directory
- cd /usr/src/the_tree
- rsync -avz --delete the_site::the_tree . (don't ignore the final dot - it means "the working directory")
Option Two. Find and download the latest bitkeeper kernel tree for PPC (bk binary v2 must be installed, see http://www.bitkeeper.com/3.6.html). As of this date, the current trees (the_tree) and their ports are:
- linuxppc_2_2, port 5001
- linuxppc_2_4, port 5000
- linuxppc_2_4_devel, port 5005
As of this date, see http://ppc.bitkeeper.com for web access. The basic command sequence to use is

cd /usr/src/
bk clone bk://ppc.bitkeeper.com:the_port the_tree to get the first download
[the_tree directory will be created for you]
cd the_tree
bk -r get -q to make the tree usable
bk pull bk://ppc.bitkeeper.com:the_port for incremental updates
bk parent bk://ppc.bitkeeper.com:the_port to revert to the current version
Note: you can also rsync the bk tree, albeit at the loss of its "bk-ness":
- cd /usr/src/the_tree
- rsync -avz --delete source.mvista.com::the_tree . (as described above)

Option Three. Download the latest official Linus-blessed kernel, linux-*.tar.gz, from an ftp.kernel.org mirror site (I personally like the one in Mexico). The basic command sequence to use is
- mv linux-*.tar.gz /usr/src
- cd /usr/src
- tar xzvf linux-*.tar.gz
- mv linux linux-*
N.B. !!! A cutting-edge kernel may not build successfully on a cutting-edge Mac; the bitkeeper/rsync kernels (see above) may be required for compatibility with newer Mac hardware or peripheral devices, especially if the kernel itself is relatively new.

building a new Linux kernel

Before beginning, rename the source directory to linux. More acceptable is to use a symbolic link called linux to point to the source directory. Some kernel builds have been known to fail if the top level of the source directory is not /usr/src/linux.

Execute the following sequence:

cd /usr/src/linux (enter the linux directory)

apply patches if necessary; for example:

de4x5.c patch (obsolete!)
mol patch for running Mac-on-Linux on 603 processors (obsolete!)

make distclean (clean up the unzipped distribution)

distclean = clean + several additional removes
distclean = mrproper + 1 additional remove
mrproper = clean + several additional removes
get it? distclean is all you should need

make menuconfig or make xconfig (inspect/change any build configuration settings)

reads the default arch/ppc/defconfig configuration
- menuconfig is a console-based menu-driven format
- xconfig is a GUI for the X environment

Note: make pmac_config will still work for kernels through 2.2.18 but is obsolete for 2.4.x. The sequence make common_config oldconfig can be used to get the "old style" challenge-response format, but unless there are new settings to be assigned, one may have to edit the defconfig file by hand to get the configuration desired.

make dep (set up dependencies)

make vmlinux (make the kernel)

Linux books discuss making zImage or bzImage. These are compressed kernels which must be used with Wintel boxes because the kernel has to fit in a limited memory space (Bill Gates' 640k strikes again?). As a ppc-hardware user, you have no such archaic constraints. Other arguments will build floppy kernels etc.

make modules (make the modules)
make modules_install (install the modules in /lib/modules/*)

Install the resulting vmlinux and System.map in the appropriate places. See install/upgrading kernel for more information.

rapierbit