I downloaded the tarball of 2.6.3 from Kernel.org as I couldn’t get my hands on the RPM that came with the install (it is not my server). I extracted it to /usr/src and I created a few sym links so now my /usr/src looks like this:
linux-2.6.3 <= This is the real file
linux-2.6
linux-2.6.3-7mdk
Yeah, well it’s not there, is it - the source code for the kernel you’re using, that is. So it won’t find it.
The build software is looking for the source code for the 2.6.3-7mdk kernel - which is not the same as the 2.6.3 kernel. And there’s no point bodging it up to make it look like it is, because you’re only likely to make more problems for yourself.
The 2.6.3-7mdk kernel will most likely have various patches applied that aren’t in the stock 2.6.3 kernel. You’ll need to d/l the proper source package from mandrake. Try using rpmfind.net to find it.