Gentoo Kernel upgrade / build

kernel_upgrade.sh

eselect kernel list
eselect kernel set #

# Use current kernel config and store copy
gunzip /proc/config.gz -c > /root/config; cp /root/config /root/config-$(uname -r)

#  Optionally change module settings in the config file, or use --menuconfig
#  with genkernel.
genkernel --makeopts=-j9 --splash --kernel-config=/root/config all

# Update packages with kernel modules
emerge -1 @module-rebuild

# Cleanup old files
for name in $(ls /lib/modules/ | sort -V | head -n -3); do
  rm -rf /boot/{initramfs,kernel,System.map}-genkernel-x86_64-${name:?}
  rm -rf /lib/modules/${name:?}
done

# Update boot config file
grub-mkconfig -o /boot/grub/grub.cfg