Platform confusion

The first thing to note is that the 7043-140 is a PReP machine. Some confusion has arisen because there was a patch some time ago that frigged the kernel to bring the machine up in CHRP mode. This never really worked very well (although I was overjoyed at the time because it was the first time I got Linux going on my machine). So, when following any instructions provided by your chosen distribution, remember your machine is a PReP machine.

Limitations

The PReP boot loader only works on the serial console. The boot loader displays a boot prompt that allows you to enter the kernel command line arguments. Any errors early in the boot process will also be displayed there. Because of this, at least when you are starting out, you should use a dumb terminal or PC with NULL-modem cable connected to the serial port. Once everything is working you can then disconnect this, if required.

When more the 512MiB of memory is installed in the 7043-140, the system changes to a different memory map, which the PReP kernel does not handle, so you if you have more than 512MiB you will have to take some out, sorry!

Update your firmware

You machine needs to be running firmware version TIG99292 or above. You can get the latest firmware from IBM here. Make sure you read the instructions carefully before updating your firmware!

Getting a firmware prompt

In order to configure the firmware, or manually load a boot image, you must get to a firmware prompt. To do this, power on or reboot the machine. After a few moments the firmware will display a series of icons (graphics console) or the words "memory", "keyboard", "network", "speaker", "ok" (serial console). After the keyboard icon or text appears, press F8 (graphics console) or 8 (serial console), and when all the icons or text have been displayed, you will be presented with the firmware prompt "0 >".

Configuring the firmware

The firmware has a number of configuration variables that control the behaviour of the machine. A couple of these are critical to ensuring that the PReP kernel can be loaded correctly. They are:

• load-base - the address the boot image is loaded at
• real-base - the address of the firmware's private storage

These are the settings that I recommend:

load-base	1000000
real-base	c00000

This is another combination that I have seen recommended:

load-base	200000
real-base	c00000

Use the setenv command to set a firmware variable, and the printenv command to display the current value. It may be worth making a note of the current values in case you want to restore their values at a later time. Here is an example:

0 > setenv load-base 1000000  ok
0 > setenv real-base c00000  ok
0 > printenv load-base
load-base                1000000             600000
 ok
0 > printenv real-base
real-base                c00000              -1
 ok
0 >

Loading a boot image

The boot command is used to load a PReP boot image. The boot image can be stored directly on a floppy, as a file on a floppy (DOS 8.3 format only), on a PReP boot partition (type 0x41), or on a CD-ROM. The commands to use for each of these cases are shown below:

Raw floppy	boot floppy:
File on a floppy	boot floppy:,\dosfilen.ame
PReP boot partition	boot disk:
CD-ROM	boot cdrom:

Please note that CD-ROMs need to be specially prepared with a PReP boot partition in order to boot on these machines. The manual page for cdrecord has some information on this if you are interested.

Next steps

You should be ready to install Linux on your machine at this point. You must decide which distribution you wish to install. I have a few pointers on this on my distributions page. Also see my walkthroughs (listed on the left).

More to come...