Ok... to me that error looks like the kernel doesn't have the support for you disk controller compiled in and therefore cannot read your root partition. If sda2 is your root partition, there are a couple of ways around this problem.
First, build a kernel from source that has the support for your disk controller compiled in, not as a module. There are many resources available for help you to build a new kernel.
Second, the kernel might have the drivers for the controller built as a module. If that is the case, you would need to make an initrd file which will attempt to load that driver before the kernel attempts to mount the root partition. Once again there are many resources available online to help with that.
Personally, I recommend compiling a kernel with the disk controller drivers compiled into it and not as a module.
Hope this help