7 ms·

My humble boot installer, no explicit bootloader, straight to the kernel: #!/bin/bash set -ueo pipefail # Remount EFI partition read/write and res

by oxplot 4y ago

My humble boot installer, no explicit bootloader, straight to the kernel: #!/bin/bash set -ueo pipefail # Remount EFI partition read/write and restore to readonly when done trap 'mount /sys/firmware/efi/efivars/ -o ro,remount &>/dev/null || true' EXIT mount /sys/firmware/efi/efivars/ -o rw,remount &>/dev/null || true # Remove all existing Arch Linux entries efibootmgr | grep 'Arch Linux' | grep -Po 'Boot\K\d+' | while read -r bn; do efibootmgr --delete-bootnum -b "$bn" &> /dev/null done || true # Install boot entry efibootmgr --verbose \ --create --disk /dev/disk/by-id/nvme-abcdef --part 1 --label "Arch Linux" \ --loader /vmlinuz-${_linux} \ --unicode "initrd=\\intel-ucode.img initrd=\\initramfs-linux.img OTHER-KERNEL-BOOT-PARAMS" EDIT: added initrd boot params

csdvrx 4y ago
If you want to add an initrd, create an EFI payload: https://wiki.archlinux.org/title/Unified_kernel_image#Manually https://wiki.archlinux.org/title/Unified_kernel_image#Manual... $ stub_line=$(objdump -h "/usr/lib/systemd/boot/efi/linuxx64.efi.stub" | tail -2 | head -1) $ stub_size=0x$(echo "$stub_line" | awk '{print $3}') $ stub_offs=0x$(echo "$stub_line" | awk '{print $4}') $ osrel_offs=$((stub_size + stub_offs)) $ cmdline_offs=$((osrel_offs + $(stat -c%s "/usr/lib/os-release"))) $ splash_offs=$((cmdline_offs + $(stat -c%s "/etc/kernel/cmdline"))) $ linux_offs=$((splash_offs + $(stat -c%s "/usr/share/systemd/bootctl/splash-arch.bmp"))) $ initrd_offs=$((linux_offs + $(stat -c%s "vmlinuz-file"))) $ objcopy \ --add-section .osrel="/usr/lib/os-release" --change-section-vma .osrel=$(printf 0x%x $osrel_offs) \ --add-section .cmdline="/etc/kernel/cmdline" \ --change-section-vma .cmdline=$(printf 0x%x $cmdline_offs) \ --add-section .splash="/usr/share/systemd/bootctl/splash-arch.bmp" \ --change-section-vma .splash=$(printf 0x%x $splash_offs) \ --add-section .linux="vmlinuz-file" \ --change-section-vma .linux=$(printf 0x%x $linux_offs) \ --add-section .initrd="initrd-file" \ --change-section-vma .initrd=$(printf 0x%x $initrd_offs) \ "/usr/lib/systemd/boot/efi/linuxx64.efi.stub" "linux.efi" The resulting linux.efi" can be added directly with efibootmgr, and contains the kernel boot parameters (cmdline)
- oxplot 4y ago
  uh - you just specify the location of your initramfs in the kernel boot params and that's it, no need for all the above
  - csdvrx 4y ago
    You hadn't specified it at first, so I thought it might be helpful to provide a more complete example with different parts (like the initrd) and offsets, with a gummiboot stub
  - still_grokking 4y ago
    Having kernel and initrd separate makes things more complicated and brittle. Also a secure boot setup is much more difficult this way. I for my part love the UKI. Never had a simpler boot setup!
    - qu4z-2 4y ago
      > a secure boot setup is much more difficult this way. Is it? Don't you just sign the bootable kernel image that already has the initrd and command-line built in? Oh, I guess if you're using Microsoft as a CA I can see why that would be tricky.
      - still_grokking 4y ago
        I think this is a misunderstanding. I've said secure boot is much more difficult in case kernel and initrd are separate. In case of a UKI it's very simple of course. Just sign the boot image. That's why I love the UKI. :-)

by oxplot 4y ago

csdvrx 4y ago

If you want to add an initrd, create an EFI payload: https://wiki.archlinux.org/title/Unified_kernel_image#Manually https://wiki.archlinux.org/title/Unified_kernel_image#Manual... $ stub_line=$(objdump -h "/usr/lib/systemd/boot/efi/linuxx64.efi.stub" | tail -2 | head -1) $ stub_size=0x$(echo "$stub_line" | awk '{print $3}') $ stub_offs=0x$(echo "$stub_line" | awk '{print $4}') $ osrel_offs=$((stub_size + stub_offs)) $ cmdline_offs=$((osrel_offs + $(stat -c%s "/usr/lib/os-release"))) $ splash_offs=$((cmdline_offs + $(stat -c%s "/etc/kernel/cmdline"))) $ linux_offs=$((splash_offs + $(stat -c%s "/usr/share/systemd/bootctl/splash-arch.bmp"))) $ initrd_offs=$((linux_offs + $(stat -c%s "vmlinuz-file"))) $ objcopy \ --add-section .osrel="/usr/lib/os-release" --change-section-vma .osrel=$(printf 0x%x $osrel_offs) \ --add-section .cmdline="/etc/kernel/cmdline" \ --change-section-vma .cmdline=$(printf 0x%x $cmdline_offs) \ --add-section .splash="/usr/share/systemd/bootctl/splash-arch.bmp" \ --change-section-vma .splash=$(printf 0x%x $splash_offs) \ --add-section .linux="vmlinuz-file" \ --change-section-vma .linux=$(printf 0x%x $linux_offs) \ --add-section .initrd="initrd-file" \ --change-section-vma .initrd=$(printf 0x%x $initrd_offs) \ "/usr/lib/systemd/boot/efi/linuxx64.efi.stub" "linux.efi" The resulting linux.efi" can be added directly with efibootmgr, and contains the kernel boot parameters (cmdline)

oxplot 4y ago
uh - you just specify the location of your initramfs in the kernel boot params and that's it, no need for all the above
- csdvrx 4y ago
  You hadn't specified it at first, so I thought it might be helpful to provide a more complete example with different parts (like the initrd) and offsets, with a gummiboot stub
- still_grokking 4y ago
  Having kernel and initrd separate makes things more complicated and brittle. Also a secure boot setup is much more difficult this way. I for my part love the UKI. Never had a simpler boot setup!
  - qu4z-2 4y ago
    > a secure boot setup is much more difficult this way. Is it? Don't you just sign the bootable kernel image that already has the initrd and command-line built in? Oh, I guess if you're using Microsoft as a CA I can see why that would be tricky.
    - still_grokking 4y ago
      I think this is a misunderstanding. I've said secure boot is much more difficult in case kernel and initrd are separate. In case of a UKI it's very simple of course. Just sign the boot image. That's why I love the UKI. :-)