docs(meta): Adjust for UEFI/legacy BIOS difference (#5)

README.md

@@ -12,7 +12,7 @@ On a UEFI system ensure these conditions are met. See [How to prep](#how-to-prep
 
 - One GPT-partitioned disk
 - Arch Linux live CD ISO image sees exactly one partition with partition type code `BF00` ("Solaris root")
-- Arch Linux live CD ISO image sees exactly one partition with partition type code `EF00` ("EFI system partition")
+- Arch Linux live CD ISO image sees exactly one partition with partition type code `EF00` ("EFI System Partition")
 - The `EF00` EFI partition is mountable, in practical terms this usually only means it has a file system.
 - No ZFS zpool exists
 
@@ -26,11 +26,17 @@ If you are instead running a legacy BIOS machine ensure these conditions are met
 - The `83` Linux partition is mountable, in practical terms this usually only means it has a file system.
 - No ZFS zpool exists
 
+Neither with a UEFI nor legacy BIOS system are any of these conditions a requirement from ZFSBootMenu. We're just setting requirements to easily identify if you intend to do a UEFI or a legacy BIOS install. Subsequently the script has no logic to detect UEFI or legacy BIOS mode, that's legwork left to the reader :) The Internet seems to agree that a good quick check is to see if your Arch Linux live CD ISO image has directory `/sys/firmware/efi`.
+```
+[ -d /sys/firmware/efi ] && echo 'Likely a UEFI system' || echo 'Probably a legacy BIOS system'
+```
+If you're unsure nothing's stopping you from just giving it a go with a best guess and if that fails you know you guessed wrong.
+
 ## How to prep
 
 ### UEFI
 
-On a blank example disk `/dev/sda` you can fulfill the UEFI requirements (One `EF00` partition with a file system plus one `BF00` partition) for example like so:
+On a blank example disk `/dev/sda` you can fulfill the UEFI requirements (one `EF00` partition with a file system plus one `BF00` partition) for example like so:
 ```
 sgdisk --new '1::+512M' --new '2' --typecode '1:EF00' --typecode '2:BF00' /dev/sda
 mkfs.vfat /dev/sda1
@@ -39,7 +45,7 @@ mkfs.vfat /dev/sda1
 >
 > `--new '2'`: Create partition number `2`. Both field number 2, the start sector, and field number 3, the end sector, are unspecified, there's no field separator `:`. Field number 2 will be the first free sector - in this case right after partition 1 - and field number 3 will be end of disk. Thus partition `2` will fill the remaining free disk space.
 >
-> `--typecode '1:EF00'`: Partition 1 gets partition type code `EF00`, an EFI system partition.
+> `--typecode '1:EF00'`: Partition 1 gets partition type code `EF00`, an EFI System Partition.
 >
 > `--typecode '2:BF00'`: Partition 2 gets partition type code `BF00`, a Solaris root partition.
 
@@ -54,12 +60,12 @@ NAME         SIZE FSTYPE PARTTYPE                             PARTTYPENAME PTTYP
 
 ### Legacy BIOS
 
-For a legacy BIOS machine you'll be using a master boot record (MBR) on your disk.
+For a legacy BIOS machine you'll be using a Master Boot Record (MBR) on your disk.
 ```
 printf -- '%s\n' 'label: dos' 'start=1MiB, size=512MiB, type=83, bootable' 'start=513MiB, size=+, type=bf' | sfdisk /dev/sda
 mkfs.vfat /dev/sda1
 ```
-> `label: dos`: Create the following partition layout in a master boot record.
+> `label: dos`: Create the following partition layout in a Master Boot Record.
 >
 > `start=1MiB, size=512MiB, type=83, bootable`: Partition 1 begins 1 Mebibyte after disk start and is 512 Mebibyte in size. We're setting its bootable flag and setting partition type code `83` ("Linux").
 >
@@ -74,13 +80,15 @@ NAME         SIZE FSTYPE PARTTYPE PARTTYPENAME PTTYPE
 └─/dev/sda2  9.5G        0xbf     Solaris      dos
 ```
 
-## ZFS dataset layout
+# Partition naming
 
-The script will create a single ZFS zpool `zpool` on the `BF00` partition with dataset child `zpool/root` which itself has one child `zpool/root/archlinux`, that's where Arch Linux gets installed. Parallel to `zpool/root` it'll create `zpool/data` with a `zpool/data/home` child dataset that gets mounted at `/home`.
+Since this script works with UEFI and legacy BIOS mode we'll be addressing both disk layout schemes with umbrella terms for better readability: "The zpool partition" will be GPT `BF00` partition and MBR `bf` partition. You'll parse the text accordingly. "The boot partition" will be GPT `EF00` partition as well as the MBR `83` partition.
 
-The script will use the `EF00` partition to install a ZFSBootMenu EFI executable if `efibootmgr` says that no such `ZFSBootMenu` entry exists. If ZFSBootMenu gets added to the EFI partition it'll become primary boot option.
+# ZFS dataset layout
 
-## How to run this?
+The script will create a single ZFS zpool `zpool` on the zpool partition with dataset child `zpool/root` which itself has one child `zpool/root/archlinux`, that's where Arch Linux gets installed. Parallel to `zpool/root` it'll create `zpool/data` with a `zpool/data/home` child dataset that gets mounted at `/home`.
+
+# How to run this?
 
 - Boot an Arch Linux live CD ISO image
 - Run:
@@ -89,9 +97,9 @@ The script will use the `EF00` partition to install a ZFSBootMenu EFI executable
     ```
     During execution the script will call itself when it changes into its `chroot`, that's why we `export SCRIPT_URL`. Feel free to update `"${SCRIPT_URL}"` with whatever branch or revision you want to use from [quico.space/quico-os-setup/arch-zbm](https://quico.space/quico-os-setup/arch-zbm). Typically `.../branch/main/setup.sh` as shown above is what you want.
 
-### Options
+## Options
 
-#### Compression
+### Compression
 
 By default we create a zpool with ZFS property `compression=on`. If the `lz4_compress` pool feature is active this will by default enable `compression=lz4`. See `man 7 zfsprops` for example in ZFS 2.1.9 for details. See `zpool get feature@lz4_compress <pool>` to check this feature's status on your `<pool>`.
 
@@ -100,7 +108,7 @@ To get a zpool with uncompressed datasets export the shell variable `ARCHZBM_ZFS
 export ARCHZBM_ZFSPROPS_NO_COMPRESSION=yesplease
 ```
 
-#### Encryption
+### Encryption
 
 By default we encrypt the zpool with ZFS property `encryption=on`. In ZFS 2.1.9 this defaults to `encryption=aes-256-gcm`.
 
@@ -109,19 +117,23 @@ To get a zpool with unencrypted datasets export the shell variable `ARCHZBM_ZFSP
 export ARCHZBM_ZFSPROPS_NO_ENCRYPTION=yup
 ```
 
-## Steps
+# Steps
 
 The script takes the following installation steps.
 
 1. Install ZFS tools and kernel module with [github.com/eoli3n/archiso-zfs](https://github.com/eoli3n/archiso-zfs)
-1. Create one ZFS zpool on top of `BF00` partition, encrypted and compressed datasets, password `password`
+1. Create one ZFS zpool on top of zpool partition, encrypted and compressed datasets, password `password`
     1. _See paragraphs [Compression](#compression)/[Encryption](#encryption) to optionally disable properties_
 1. Create dataset for Arch Linux and `/home`
 1. Install Arch Linux into pool
-1. Add ZFSBootMenu to `EF00` partition if it doesn't exist already
+1. Add ZFSBootMenu to boot partition
+1. Configure boot method
+    - Either an EFI image with EFI boot order entries on a UEFI machine
+    - Or Syslinux with `extlinux` for a legacy BIOS computer
+1. Add `pacman` hooks to keep ZFSBootMenu images (and `extlinux`) updated
 1. Exit into Arch Linux live CD ISO image shell for you to `reboot` and frolick
 
-## Flavor choices
+# Flavor choices
 
 We make the following opinionated flavor choices. Feel free to change them to your liking.
 
@@ -133,7 +145,7 @@ We make the following opinionated flavor choices. Feel free to change them to yo
 - Timezone is `Etc/UTC`
     - Check `timedatectl set-timezone <tzdata-zone>`
 
-## Post-run manual steps
+# Post-run manual steps
 
 After installation you're going to want to at least touch these points in your new Arch Linux install:
 
@@ -507,7 +519,7 @@ Explanation:
     zpool/root            none        off       no
     zpool/root/archlinux  /mnt        noauto    yes <-- Now mounted
     ```
-- We lastly mount our EFI system partition (ESP), in this example it's living at `/dev/sda1` so adjust this path accordingly.
+- We lastly mount our EFI System Partition (ESP), in this example it's living at `/dev/sda1` so adjust this path accordingly.
 
     ```
     # df -hTP

setup.sh

@@ -220,7 +220,7 @@ function select_part () {
     if [[ ! "${parts}" ]]; then
         case "${part_type}" in
             efi)
-                part_type_human_readable='EFI system partition (ESP) with partition type code EF00'
+                part_type_human_readable='EFI System Partition (ESP) with partition type code EF00'
                 ;;
             zfs)
                 if [[ "${part_schema}" = 'mbr' ]]; then