Kernel Rebuild & Deployment Workflow
If there has been an upgrade to gentoo-sources, follow the steps below to install the new kernel correctly.
Install installkernel
echo "sys-kernel/installkernel grub" >> /etc/portage/package.use/installkernel
emerge --ask sys-kernel/installkernel
Move to the new source code
Get your current, working config
zcat /proc/config.gz > /usr/src/linux/.config
Kernel configuration migration (make olddefconfig)
Install modules and the kernel itself
make modules_install
make install
Generate new initramfs (CRITICAL for your LUKS/LVM setup)
genkernel --luks --lvm --install initramfs
Install grub:2 if its the first time you will genereate grub.cfg
grub-install --target=x86_64-efi --efi-directory=/boot --bootloader-id="Gentoo Linux"
Update grub (Since you went back to GRUB for stability)
grub-mkconfig -o /boot/grub/grub.cfg