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 in /etc/portage/package.use, it will also symlink the latest downloaded source (whether you want it to or not) to:

/usr/src/linux

So once you emerge a new kernel source, you ought to install it or change the symlink if you don't have the time to do the kernel install.

Steps To Install Kernel

su -
emerge sys-kernel/gentoo-sources
cd /usr/src/linux
make menuconfig (and configure - see Configure MythTV kernel)
make && make modules_install
mount /boot (if needed)
ls /boot
cp arch/x86_64/boot/bzImage /boot/kernel-genkernel-x86)64-#kernelversion#-gentoo-#gentooreleaseversion#_mdm-menuconfig
emacs /boot/grub/grub.conf (and add your shiny new kernel to the default top of the list)

Post-kernel-installation Steps

install nvidia binary driver
install a new ivtv that matches the new kernel version

In theory you can use the following to automatically reinstall kernel-dependent modules:

module-rebuild rebuild

But I used a more manual approach, as module-rebuild didn't work:

module-rebuild list                   # to see what it WOULD rebuild
emerge nvidia-drivers
eselect opengl set nvidia
reboot
emacs /etc/portage/package.mask       # adjust ivtv version if needed
                                      # it has to match your kernel version
                                      # comment out ivtv line to get latest version
emerge ivtv
reboot

Even better, if you have just adjusted the kernel, and not bumped up the version, just do this:

module-rebuild list                   # to see what it WOULD rebuild
emerge nvidia-drivers ivtv
eselect opengl set nvidia
reboot

If you've done an emerge of media-video/nvidia-settings, you can run it to adjust the resolution, etc., dynamically in X.