Update gentoo kernel
In gentoo, everything gets updated via portage using "emerge". For the kernel, emerge only updates the source. You have to manually configure, compile, and install the kernel source into a kernel binary. This is to allow you to keep your kernel tuned for your machine.
Gentoo installs the source here:
/usr/src/linux-#kernelversion#-gentoo-#gentooreleaseversion#
Because I have defined the "symlink" USE flag for gentoo-sources, it will also symlink the latest downloaded source (whether you want it to or not) to:
/usr/src/linux