i installed gentoo by the handbook from official site , when i got into the step 7.b. Installing the Sources , the book says :Code Listing 2.2: Viewing the kernel source symlink, When you take a look in /usr/src you should see a symlink called linux pointing to your kernel source. but ,in my virtualbox, there is no such file! ,only a linux-3..3.38-gentoo directory in the src and when i tried to use cd linux-3.3.38-gentoo and make menuconfig , an error occured , init/Kconfig:389: can't open file "kernel/irq/Kconfig" how can i solve the problem?