(parted)mkpart primary 1 3
(parted)name 1 grub
(parted)set 1 bios_grub on 
(parted)mkpart primary 3 131 
(parted)name 2 boot
(parted)mkpart primary 131 10240
(parted)name 3 swap 
(parted)mkpart primary 10240 -1 
(parted)name 4 rootfs 
(parted)set 2 boot on
mkfs.ext2 /dev/sda2
mkfs.ext4 /dev/sda4

mount /dev/sda4 /mnt/gentoo
mkdir /mnt/gentoo/boot
mount /dev/sda2 /mnt/gentoo/boot

(parted) mkpart primary 0 -1
(parted) name 1 rootfs
(parted) set 1 boot on 
(parted) set 1 bios_grub on 
mkfs.ext4 /dev/sda1 
mount /dev/sda1 /mnt/gentoo
mkdir /mnt/gentoo/boot

Failed to install sys-kernel/gentoo-sources-4.9.16