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glaucus Linux

ISO

  • Add .tar.zst packages on the install iso (rad should install to custom root, a la pacstrap)
  • Add limine, (mtools?) and parted to install iso
  • Add dosfstools, efibootmgr and gptfdisk to install iso
  • Do not add microcode or firmware to live iso?
  • Modify /etc/issue and add date and username and pass: https://www.linuxfromscratch.org/blfs/view/svn/postlfs/logon.html
  • makewhatis /usr/share/man to update man-pages
  • Prefer cat to dd

Live

  • sleep is essential to avoid race conditions
  • Mounting a device /dev/sda is type iso9660
  • Mounting a partition /dev/sda3 is type hfsplus
  • If detected as /dev/sr0 it is type iso9660
  • if detected as hard drive (usb) it is type hfsplus
  • xorriso requires -hfsplus -apm-block-size 2048 to work on a bootable USB (Hybrid setup) (default on grub-mkrescue)
  • Avoid rEFInd (fork of rEFIt from macOS)
  • Avoid EFI editors like efibootmgr, bcfg and kesboot (mess motherboard’s NVRAM and EFI)
  • EFI/BOOT should be under / and not under /boot (xorriso)
  • Recommended size of /boot and ESP: https://www.rodsbooks.com/efi-bootloaders/principles.html
  • vfat vs fat32 vs fat for ESP partition: https://uefi.org/specifications
  • Volume ID should be in capital letters according to ISO 9660 (GLAUCUS) (ECMA-119 demands ASCII characters out of A-Z0-9_)
  • Suse removed bios support from iso

Software

  • cdrtools (includes mkisofs)
  • libburnia (includes libisoburn, xorriso and cdrskin)
  • mkisofs (part of cdrtools, people switched to xorriso, license?)
  • xorrecord (emulation of cdrecord by xorriso)
  • xorrisofs (emulation of mkisofs by xorriso)

Excluded

  • cdrdao (GUI)
  • cdrecord (deprecated version of cdrtools)
  • cdrkit (deprecated fork of cdrtools, Mr. Schilling says it sucks, filled with bugs and license concerns)
  • cdw (GUI)
  • dvd+rw-tools (deprecated, aka growisofs, does not deal with CDs)
  • genisofs
  • genisoimage (deprecated, fork of mkisofs, from cdrkit)
  • wodim (deprecated, fork of cdrecord, from cdrkit)

ISO 9660 Extensions (relax limitations)

  • Apple ISO 9660 Extensions (file characteristics specific to the classic Mac OS and macOS, such as resource forks, file backup date and more)
  • El Torito (enables CDs to be bootable)
  • Joliet (Unicode, allowing non-Latin scripts to be used)
  • Rock Ridge (Unix-style permissions and longer names)

Booster

  • Does not support live environments
  • e1000 provides internet access inside QEMU, and has been added to the default booster configuration
  • After install, booster should be rerun to generate a native non-universal build

GRUB

  • Do not use --disable-shim-lock to disable shim_lock as it would render the iso not bootable when Secure Boot is enabled
  • Arch images do not support Secure Boot; disable Secure Boot to boot the install medium, and if desired, it can be set up after install
  • you can’t use more than 300k files on an ISO, which is why we have to disable hfsplus when creating ISO: -hfsplus off (This does not work with xorriso in grub-mkrescue)
  • -r enables Rock Ridge and changes file ownership to 0; using sudo without -r does not change file ownership
  • grub-mkrescue runs xorriso:
Terminal window
xorriso \
  -as mkisofs \
  -graft-points \
  --modification-date=2024053120334500 \
  -b boot/grub/i386-pc/eltorito.img \
  -no-emul-boot \
  -boot-load-size 4 \
  -boot-info-table \
  --grub2 \
  -boot-info \
  --grub2-mbr /usr/lib/grub/i386-pc/boot_hybrid.img \
  -hfsplus -apm-block-size 2048 \
  -hfsplus-file-creator-type chrp tbxj /System/Library/CoreServices/.disk_label \
  -hfs-bless-by i /System/Library/CoreServices/boot.efi \
  --efi-boot efi.img \
  -efi-boot-part \
  --efi-boot-image \
  --protective-msdos-label \
  -o glaucus.iso \
  -r /tmp/grub.yu5TLx \
  --sort-weight 0 / \
  --sort-weight 1 \
  /boot iso $APPENDED_OPTIONS
  • Previous grub-mkrescue command to generate glaucus iso
Terminal window
# `-boot-info-table` can only be used when an argument is passed with `-b`
# `-R` is enabled by default by `xorrisofs`
# `-pad` is enabled by default by `xorrisofs`
# `-cache-inodes` is a relic from `genisoimage`, ignored by `xorriso`
# `-hfsplus off` does not work with `grub-mkrescue`
# `-no-hfs` does not work with `grub-mkrescue`
# `-d`, `-omit-period` violates iso9660
# `-N`, `-omit-version-number` violates iso9660
# `-max-iso9660-filenames` violates iso9660
# `-relaxed-filenames` violates iso9660
# `-allow-lowercase` violates iso9660


grub-mkrescue \
  --compress=no \
  --fonts="" \
  --locales="" \
  --themes="" \
  -v \
  --core-compress=none \
  -o glaucus.iso \
  --product-name glaucus \
  --product-version glaucus \
  $1 \
  -A glaucus \
  -iso-level 3 \
  -J \
  -joliet-long \
  -l \
  -pad \
  -publisher glaucus \
  -p glaucus \
  -R \
  -r \
  -V GLAUCUS \
  -vv

fstab

  • The number before last in the table structure is an outdated backup method and should not be used (kept 0)
  • The last number in the table is the File System Check Order: (second digit).  0 means that fsck will not check the filesystem. Numbers higher than this represent the check order. The root filesystem should be set to 1 and other partitions set to 2.
  • Consider the following fstab for EROFS/overlayfs:
Terminal window
/iso/fs /media/fs-ro erofs   defaults,loop                                                                        0 0
overlay /            overlay defaults,lowerdir=/media/fs-ro,upperdir=/media/fs-rw/upper,workdir=/media/fs-rw/work 0 0

OverlayFS (rw)

  • lower should be ro
  • upper and work should be rw in a tmpfs space like /run and not in something like /media (cdrom can be kept in /media though)
  • switch_root is responsible for moving proc, dev and sys to the new root

Alpine

  • Uses grub for efi and isolinux for bios
  • SquashFS inside boot called modloop is mounted on /.modloop using /dev/loop0
  • tmpfs mounted on / for rw
  • Installs packages in apks directory

Arch

  • systemd-boot for efi and isolinux for bios

Kiss

  • no rootfs; either the initramfs is being used directly or packages are being extracted at boot time?
  • requires at least 2 GB of RAM to boot to extract all the packages
  • ram on / type tmpfs
  • base install packages in pkgs

Resources