# How to install slackware64-current on a ZFS root

# PREREQUISITES
# - EFI machine
# - a disk that can be wiped fully
# - USB-stick created with https://github.com/tterpelle/docker-slack64-current-zfs
# - you've read and understood https://github.com/zfsonlinux/zfs/wiki/Debian-Stretch-Root-on-ZFS
#
# Note1: only create a mountpoint for your / dataset, create the other datasets as 'legacy':
# zfs create -o mountpoint=legacy ${ZPOOL}/home
#
# Note2: create a swap partition if you want to be able to hibernate (pm-hibernate) your system.
# It should be at least the size of your RAM.

# You've booted the USB-stick and are now in the Slackware64-current installer shell.
# Press ALT+F2 to open a terminal on tty2, for some reason it will not open on tty1.

# Here we go!

# Empty /mnt because ZFS (by default) refuses to mount over non-empty directories
rm /mnt/README

# Search for your target disk in /dev/disk/by-id and save it in variable
export TARGET="/dev/disk/by-id/scsi-SATA_disk1"

# Choose a name for your ZFS pool and save it in a variable
export ZPOOL=rpool

# WIPE ALL THE THINGS on your target disk
mdadm --zero-superblock --force ${TARGET}
sgdisk --zap-all ${TARGET}
zpool labelclear -f ${TARGET}

# Create EFI, swap and ZFS partitions
sgdisk     -n2:1M:+100M  -t2:EF00 ${TARGET}
sgdisk     -n3:0:$(free -m | grep Mem | awk '{ print $3 }')M       -t3:8200 ${TARGET}
sgdisk     -n4:0:0       -t4:BF01 ${TARGET}

# Create ZPOOL
zpool create -o ashift=12 -d \
      -o feature@async_destroy=enabled \
      -o feature@bookmarks=enabled \
      -o feature@embedded_data=enabled \
      -o feature@empty_bpobj=enabled \
      -o feature@enabled_txg=enabled \
      -o feature@extensible_dataset=enabled \
      -o feature@filesystem_limits=enabled \
      -o feature@hole_birth=enabled \
      -o feature@large_blocks=enabled \
      -o feature@lz4_compress=enabled \
      -o feature@spacemap_histogram=enabled \
      -O acltype=posixacl -O canmount=off -O compression=lz4 \
      -O normalization=formD -O relatime=on -O xattr=sa \
      -O mountpoint=/ -R /mnt \
      ${ZPOOL} ${TARGET}-part4

# Create datasets, see "Debian Stretch Root on ZFS" for more info
zfs create -o canmount=off -o mountpoint=none ${ZPOOL}/ROOT
zfs create -o canmount=noauto -o mountpoint=/ ${ZPOOL}/ROOT/linux
zfs create mountpoint=legacy ${ZPOOL}/ROOT/home
zfs create mountpoint=legacy ${ZPOOL}/ROOT/opt
zfs create mountpoint=legacy ${ZPOOL}/ROOT/tmp
zfs create mountpoint=none ${ZPOOL}/ROOT/var
zfs create mountpoint=legacy ${ZPOOL}/ROOT/var/tmp
zfs create mountpoint=legacy ${ZPOOL}/ROOT/var/log
# ...

# Mount the datasets
zfs mount ${ZPOOL}/ROOT/linux
for dir in tmp home var/log var/tmp opt
do
  mkdir -pv /mnt/${dir}
  mount -t zfs ${ZPOOL}/${dir} /mnt/${dir}
done

# Format and mount EFI partition
mkdir -pv /mnt/boot/efi
mkfs.vfat -F32 ${TARGET}-part2
mount ${TARGET}-part2 /mnt/boot/efi

# Format swap partition
mkswap ${TARGET}-part3

# Install Slackware but DO NOT REBOOT when it's finished,
# we still have to make the system bootable
setup

# Install ZFS and SPL packages in /boot/initrd-tree so be included in initrd
# TODO: optimize this step, the initrd doesn't need the entire content of
#       the packages.
installpkg --root /mnt/boot/initrd-tree \
  /usb-stick/slackware64/a/zfs-on-linux-* \
  /usb-stick/slackware64/a/spl-solaris-*

# Copy patches to new system
cp /usb-stick/zfs/*.patch /mnt/tmp

# Chroot into fresh system
chroot /mnt /bin/bash

# Create mkinitrd.conf
cat <<EOF > /etc/mkinitrd.conf
SOURCE_TREE="/boot/initrd-tree"
CLEAR_TREE="0"
OUTPUT_IMAGE="/boot/initrd.gz"
KERNEL_VERSION="\$(uname -r)"
KEYMAP="us"
MODULE_LIST="zfs"
RESUMEDEV="UUID=$(blkid -t TYPE=swap -s UUID -o value)"
ROOTDEV="${ZPOOL}/ROOT/linux"
ROOTFS="zfs"
UDEV="1"
EOF

# Copy required .so for zpool to initrd
cp /usr/lib64/libgcc_s.so* /boot/initrd-tree/usr/lib64

# Add ZFS support to boot scripts
patch /boot/initrd-tree/init < /tmp/init.zfs.patch
patch /etc/rc.d/rc.S < /tmp/rc.S.zfs.patch

# Create initrd
mkinitrd -F /etc/mkinitrd.conf

# Install GRUB
export ZPOOL_VDEV_NAME_PATH=YES
grub-install ${TARGET}
grub-mkconfig -o /boot/grub/grub.cfg

# Create /etc/fstab
cat /etc/mtab >> /etc/fstab
vi /etc/fstab

# Exit chroot
exit

# Clean up
for dir in boot/efi home opt tmp var/log var/tmp sys proc dev
do
  umount -flv /mnt/${dir}
done

zfs umount -a
zpool export -a

# Reboot
reboot