Boot Sequence Links

For general interest, here’s some info on booting, LUKS, GRUB, their interactions etc.
If you see errors or have other good stuff, drop it in.

I currated this through my living hell here :


BIOS: Basic Input Output Stream

EPROM: Erasable Programmable Read Only Memory

GRUB: GRand Unified Bootloader


PureOS :

  1. SeaBIOS
    Lives on EPROM chip since it controls disks (can’t live on one), and needs acces pre-boot (can’t live in RAM)

  2. GRUB
    Lives one of many places ( boot block, boot partition, {OS_ROOT}/boot, on a USB, packages, stuffed and signed to EPROM…) allows for selection of kernel to load and handoff to.


BIOS / Bootloaders



INFO & TUTORIALS (man is your friend)

General boot etc…

GRUB Manual
man update-initramfs
update-initramfs -c -kall

LUKS / Encryption

man cryptsetup

curious about what’s available? -> cryptsetup benchmark

Concise explanation of available ciphers and how to compare them on your system.
Good description of key create/decrypt routine
(Old) discussion about LUKS ciphers
(Old) pretty good explanation of how ciphers apply to LUKS


man grub-install
man grub-mkimage
man grub-mkconfig

man these too!


grub-bios-setup grub-install grub-macbless grub-mkconfig grub-mkdevicemap grub-probe grub-reboot grub-set-default


update-grub update-grub2 upgrade-from-grub-legacy grub-editenv grub-file grub-fstest grub-glue-efi grub-kbdcomp grub-menulst2cfg grub-mkfont grub-mkimage grub-mklayout grub-mknetdir grub-mkpasswd-pbkdf2 grub-mkrelpath grub-mkrescue grub-mkstandalone grub-mount grub-ntldr-img grub-render-label grub-script-check grub-syslinux2cfg

LUKS, Linux, LVM

someone’s notes from above

PureOS specific

PureOS installation issues

What works (as of 11/10/2019), current Live installer:

  • ERASE DISK install with Encryption
  • ERASE DISK install with NO Encyption
  • The methods here although you get a dinky /boot that’s too small for a grub-install /dev/sda and cannot use Adnvanced method to LUKS anything, currently (bugs out on a /tmp read only mount)

What doesn’t work:

  • Nearly any other configuration or option.

May, 2019: T750 Partitioning is WHACK!
April, 2019: T751 Partitioning is WHACK!
April, 2019: T752 Partitioning is WHACK!
April, 2019: T778 Partitioning is WHACK!
May, 2018 OEM is gramattically/syntactically confusing!


…which seems cool maybe

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