YOU MUST DISABLE the SIMPLE BOOT flag FOR Linux!
On a ThinkPad, enabling Simple Boot does much the same thing as setting PNP OS = Yes on most desktops. If you enable Simple Boot, you are telling the BIOS NOT to configure the devices (the CS4237B in this case) with the resources you set using PS2.EXE (or setpnp). YOU MUST DISABLE the SIMPLE BOOT flag FOR Linux!
The IBM Bios Update Instructions mention the Simple Boot flag for the following ThinkPads: 600, 600E, 600X, 770, 770E, and 770ED.
This is what IBM says about Simple Boot in the BIOS Update instructions:
Simple Boot Flag function
This function automatically optimizes the behavior and boot performance of the BIOS and operating system, based on the installed operating system and previous boot.
If this function is Enabled and once a Plug and Play-capable operating system, such as Windows 98, is installed, the system BIOS does not configure such hardware resources as system interrupts, memory ranges, and I/O port ranges for all the devices in the system.
If you are going to use a non-Plug and Play-capable operating system, disable this function so that the BIOS will configure hardware resources.
NOTE: If you are using multiple operating systems in addition to Windows 95/98, you must DISABLE the Simple Boot Flag in Easy-Setup.
To modify the Simple Boot Flag:
Retrieved from "http://alsa.opensrc.org/Thinkpad_Simple_Boot"