9. Compile a kernel

9.1. Why update the kernel

The kernel we have used this far is a complete 2.4 (2.2 for YellowDog) kernel that I have provided. This is a quite stable and good kernel, but it's not sure that it's what you want. You should make your own kernel so you know what patches you need and what modules you can install when you really need them. Here are links to all sources and patches, and a step by step guide to compile your new kernel.

As for the installation we just have done, you have to boot from floppy. Would it not have been nice to be able to boot directly off the hard disk - and by the way, what about sound support? Let's set up this together as quickly as possible.

Before starting downloading files and compiling the kernel, check that you have these packages installed:

make gcc cpp glibc-devel ncurses-devel kernel-headers

(This list should probably be longer.)

Note that the names of this packages may change slightly among the distributions.

9.2. What files to download

We'll use the latest 2.4 kernel sources with a few patches, among those the IBM-E15 frame buffer patch from David Monro, which gives us a working frame buffer console able to run XFree86. This may sound complicated, but believe me, it's not. Follow the steps below here, and we'll get you up in an hour or so.

We're going to use the standard place for linux kernels, that is /usr/src/ . When downloading the kernel source and patches, place all files in /usr/src .

First we must get the working 2.4 source. To get this, we'll use the rsync tool, so check that you have it installed. Some nice people have set up an rsync server of the BitKeeper Linux/PPC development tree at source.mvista.com. Thanks so very much to them, remember them in your heart and prayers.

Note: You may use the standard Linux kernel source from any ftp.kernel.org mirror. A modern kernel like 2.4.21 should work allright. I've found the devel tree more well functioning on the 7248, so I stick with it.

Warning: Don't do this over a low-end link, like a modem. It'll take forever. So, let's rock and roll. Issue these commands:

cd /usr/src mv linux linux.old mkdir linux-2.4 ln -s linux-2.4 linux cd linux rsync -avz --delete source.mvista.com::linuxppc_2_4_devel . chown -R root.root . chmod -R u+w .

Note that you'll probably have to wait for some minutes to rsync over all the sources. This is normal.

Then, get David Monro's IBM E15 frame buffer patch from Leigh Brown's site page at http://www.solinno.co.uk/7043-140/files/2.4.19-2/

9.3. Patching the source

The next step is to patch the source files you just downloaded. First add the IBM E15 patch:

cd /usr/src/linux patch -p1 < ../030-e15fb.diff

If you have more patches, add them the same way. Now the kernel source is ready for configuring.

9.4. Configuring the kernel

The details of configuring the kernel are way outside the scope of this document. To get more help, try The Kernel HOWTO. Here, we'll just cover the basics to get a working kernel. Download my kernel config file into the top directory of the kernel tree , /usr/src/linux .

In the top directory (/usr/src/linux) start the configuration program by issuing the following commands:

make ibmchrp_config cp ingvar.config-2.4 .config make menuconfig

Inside the kernel configuration system, we check over the different menus to get to know our possibilities. Don't be afraid to change anything. We can copy the original back, and load the configuration system again. There are a few things to check out before we go on compiling and installing:

9.5. Compiling and installing the kernel

To compile the kernel is quite straightforward. If you're not in there already, enter the linux directory in the top level of the kernel tree, and issue this command series:

cd /usr/src/linux make dep && make clean && make zImage && make modules && make modules_install

Now, go and make yourself a cup of tea or coffee or have a beer or a bible study for some minutes. This can take some time. If everything is alright, you'll finally have a kernel to install when the text stops scrolling after maybe as much as 20 minutes, depending on your kernel configuration.

Now it's time to install your fresh-baked kernel. On most Linux-based systems like, we keep kernels and their setupfiles in the /boot directory. Check what version you run with a look at the Makefile, and add proper version numbers in the commands below:

head /usr/src/linux/Makefile cp /usr/src/linux/arch/ppc/boot/images/zImage.prep /boot/vmlinuz-2.4.21 cp /usr/src/linux/System.map /boot/System.map-2.2.18

Assuming that sda1 is your boot device with a PReP Boot partition, and your kernel has version 2.4.21, install the new kernel by issuing this command:

dd if=/boot/zimage-2.4.21 of=/dev/sda1

We also want the System map link to point to our new System.map. Issue these commands:

mv /boot/System.map /boot/System.map.old ln -s /boot/System.map-2.4.21 /boot/System.map

9.6. Configure modules

Before rebooting we must send some parameters to configure the sound modules. On YellowDog, SuSE and Mandrake, this is done in /etc/modules.conf. In Debian, use /etc/modutils/sound. Edit this file, and add the following lines:

alias sound cs4232 pre-install sound /sbin/insmod sound dmabuf=1 options cs4232 io=0x534 irq=5 dma=1 dma2=0 mpuio=0x330 mpuirq=5

On Debian, run /sbin/update-modules when done.

9.7. Pray and reboot

There! We are ready to reboot. Light some candles (some people prefers to sacrifice chickens or even goats), remove the boot floppy, and issue the command:

reboot

If everything worked, the system will go down nicely, and (assuming you compiled in support for the E15 frame buffer) come up again with Tux, the Linux Penguin Mascot smiling to you while booting.