I've got a kernel module for a video output expansion card that seems to fail when running on a machine with more than 4GB installed. Until the vendor issues a patch for this I want to cap the amount of memory available to the kernel to avoid having to pull the extra memory out of my machine when I do development work on it. I run a lot of VMs the rest of the time so 8GB of main memory comes in handy.

A quick google yielded an article that says appending mem=4G to the boot parameters will do the trick. Is this all I need to do? Is this as good as pulling the memory out?