I had problems with selecting the device to use for early-networking, because apparently its name was not very stable (e.g. upgrade from Linux 2.6.26 to 2.6.32 had changed it a the time, but there was more), leading to my early networking to fail unexpectedly -- which is especially problematic if you need it to boot.

Trying once again to fix this, I noticed that the documentation of the ip kernel parameter specifies that the device might be empty and then the kernel with try to find the first that actually works:

<device> Name of network device to use. If this is empty, all
devices are used for RARP/BOOTP/DHCP requests, and the
first one we receive a reply on is configured. If you
have only one device, you can safely leave this blank.

Although this snippet is not very clear on whether it would work with a static IP, it does work just fine :)
So, if your setup has no risk of finding an inappropriate interface (e.g. if you only have one actually working in early boot) it's very handy to simply let the kernel choose for you.

"Sometimes it may be necessary to blacklist a module to prevent it from being loaded automatically by the kernel and udev. One reason could be that a particular module causes problems with your hardware. The kernel also sometimes lists two different drivers for the same device. This can cause the device to not work correctly if the drivers conflict or if the wrong driver is loaded first.

You can blacklist a module using the following syntax: module_name.blacklist=yes."