zbm-syslinux-pacman-hook

Arch Linux pacman hook to automatically recreate syslinux and MBR after updates

Setup

Get started like so:

1. Install dependencies jq and rsync
2. Clone repo into arbitrary path <repo>
3. Make pacman-zbm-syslinux-regen.sh executable

   chmod +x <repo>/pacman-zbm-syslinux-regen.sh
   

4. Symlink to files, for example

   sudo ln -s <repo>/pacman-zbm-syslinux-regen.sh /usr/local/bin/pacman-zbm-syslinux-regen
   sudo ln -s <repo>/pacman-zbm-syslinux-regen.hook /usr/share/libalpm/hooks/pacman-zbm-syslinux-regen.hook
   

   Note that while you may choose an arbitrary location for your shell script symlink pacman-zbm-syslinux-regen.hook file references /usr/local/bin/pacman-zbm-syslinux-regen. Change that accordingly if you need to.

What's it do?

In pacman whenever the syslinux package is getting updated this hook will replace all *.c32 COMBOOT module files in /boot/syslinux, will reinstall newest extlinux and write the newest mbr.bin Master Boot Record file onto the boot disk.

This happens as a PostTransaction in pacman.

We identify the boot disk via:

findmnt --noheadings --target "${boot_dir}" --output 'SOURCE'

Where "${boot_dir}" is:

boot_dir='/boot/syslinux'

If this returns zero or more than one mounted drive we bail, print an error message and do not do any operations.

Assumptions

This hook is intended to work with quico.space/quico-os-setup/arch-zbm, a root on ZFS installation script that uses ZFSBootMenu as its boot loader; it's specifically intended for use on arch-zbm machines that use legacy BIOS. Before using this hook for any other purpose please closely review what it does and adapt to your use case as needed.

We do not care about pacman events other than a syslinux package update. Specifically if ZFSBootMenu gets an update syslinux and our Master Boot Record remain unaffected. Kernel update? Same, no change needed since no kernel or module change directly influence the simple and decoupled structure of syslinux.

Development

Conventional commits

This project uses Conventional Commits for its commit messages.

Commit types

Commit types besides fix and feat are:

• build: Project structure, directory layout, build instructions for roll-out
• refactor: Keeping functionality while streamlining or otherwise improving function flow
• test: Working on test coverage
• docs: Documentation for project or components

Commit scopes

The following scopes are known for this project. A Conventional Commits commit message may optionally use one of the following scopes or none:

• script: Any other script work that doesn't specifically fall into the above scopes
• hook: Configuring the hook(s)
• meta: Affects the project's repo layout, readme content, file names etc.