I'm being working out with building KDE environment recently. 
Now I need installing Xorg first. As the <The X Server Configuration HOWTO> says,
if I use radeon card ,then I need emerge radeon-ucode or linux-firmware package.
Then I need rebuild my kernel with External firmware blobs . My video card belongs
to radeon 4000 series, so I should add "radeon/R600_rlc.bin radeon/R700_rlc.bin" as
it says into  External firmware blobs . But when I make, it says that it can't find files that I specific..
Can anyone help?