How to change the BIOS bootsplash screen
This Page describes how I replaced the standard IBM BIOS Bootsplash (The one with the Thinkpad- and Pentium M-Logo), without access to Microsoft Windows or a floppy drive. Although I just did this procedure as described, I wrote down the commends as I remembered, so beware.
Getting the Files
I got the bios upgrade diskette from the IBM site. It was an .exe-file... but no, no Windows executable, an OS/2 executable (well, it's IBM after all). And OS/2 executables don't run in wine. So I did an apt-get install dosemu dosemu-freedos (for non-debian-users: Get dosemu and freedos somewhere and make it work somehow).
With dosemu, I could run this executable. But this program unfortunately needs a floppy drive to write to. So I dig into the linux toolbox and find: The loopback device. A dd if=/dev/zero of=/tmp/floppy.bin bs=1024 count=1440 creates a file for the floppy, a losetup /dev/loop0 /tmp/floppy.bin makes it look like a block device, and this block device is what I put in the dosemu configuration as the floppy disk device. Now I can run the extractor executable (dosemu something.exe) and it will happily make /tmp/floppy.bin a floppy image.
Adding the custom image
This floppy image can be mounted (mount -o loop,umask=000 /tmp/floppy.bin /mnt/tmp), and now I can read the readme.txt. To replace the logo file, I create a 16bit 640x480 BMP file, save it as logo.bmp and run logo.bat. Just kidding, you can't just run batch files in linux, but - after testing the bitmap, which I just didn't do - that batchfile only runs prepare.exe logo.scr. This program won't run in dosemu, but in wine: wine prepare.exe logo.scr. Now there should be a new logo.mod. If so, you are set, unmount /mnt/tmp and go on.
Fake a floppy
Now I need to put the image on a floppy and boot. Since I don't have a floppy (and no floppy drive after all), I use a CD-R (a CD-RW, actually, for the cheap ones, like me) and burn it like that: cd /tmp; mkisofs -b floppy.bin floppy.bin | cdrecord -dev=<irgendwas> -
The exciting part
After this worked, I rebooted from the cdrom and the IBM tool started. After confirming that I checked a few things, I got asked whether I want to replace the boot splash image. Yes, I do. It will then flash the BIOS, which will take about a minute. A hint: Since you know that any problem during this minute might break your thinkpad, if you have weak nerves, go and do something else instead of watching a non-changeing screen.
Suddenly the laptop turns itself off. Hopefully, it was finished - in my case it was. When booting, I got my bootsplash picuture (with some ugly text "To abort booting, press Enter" or something in the lower left corner). Unfortunately, you don't see it really long, but it's better than some advertisement, so it was worth it.
This text was meant as a immidiate mailinglist post, feel free to improve :-)