> Do not put the kernel source under /usr/src. Search Google if you want
> to know why.
> 

I searched Google and found that the Debian Reference manual suggests
that /usr/src is the correct location.  I couldn't find any reason not
to have the kernel compiled from /usr/src/.

http://www.google.com/search?q=Do%20not%20put%20the%20kernel%20source%20under%20%2Fusr%2Fsrc

http://www.sdn.or.id/share/Debian-Doc/manuals/debian-reference/ch-kernel.en.html#s-kernel-debian