====== Boot Grml from Harddisk ======

===== Preface =====

The [[http://grml.org/|Grml]] rescue system supports booting the Grml ISO from a hard disk. This provides a decent way to have a Grml ISO in /boot/grml/ on your hard disk and as long as the hard disk and its GRUB boot loader is working you can boot the Grml rescue system without having a rescue CD, USB pen or PXE environment available.

To make this task as easy as possible we've created **grml-rescueboot** which integrates ISO-booting into GRUB. The grml-rescueboot package includes a script for update-grub which looks for Grml ISO images in /boot/grml and automatically adds an entry for each image.

===== Requirements =====

  * Grml ISO
  * GRUB2 bootloader

===== Installation of grml-rescueboot =====

grml-rescueboot is available via 'apt-get install' in Debian/wheezy and Debian/sid and Ubuntu precise/universe and Ubuntu quantal/universe:

  apt-get install grml-rescueboot

If you're running Debian/squeeze you can just use [[http://packages.debian.org/sid/all/grml-rescueboot/download|the grml-rescueboot package from Debian wheezy/sid]].

If you're using a different system/distribution the following commands should set up grml-rescueboot for you:

  wget -O /etc/default/grml-rescueboot https://raw.github.com/grml/grml-rescueboot/master/etc/default/grml-rescueboot
  wget -O /etc/grub.d/42_grml https://raw.github.com/grml/grml-rescueboot/master/42_grml
  chmod 755 /etc/grub.d/42_grml

Note: we'd love to see grml-rescueboot being available outside of Debian and Ubuntu as well, if you're interested in providing RPMs, ebuilds, arch packages,... please [[http://grml.org/contact/|let us know]]!

===== Setup of grml-rescueboot =====

Once you've install the grml-rescueboot package the setup is as simple as:
  
  cd /boot/grml
  wget http://download.grml.org/grml64-full_2012.05.iso
  wget http://download.grml.org/grml64-full_2012.05.iso.sha1
  sha1sum -c grml64-full_2012.05.iso.sha1
  update-grub

===== Customisation of Bootoptions ====

To be able to access the harddisk of the system you're booting from you need to load the ISO into RAM (using the //toram// bootoptions). You also might want to autostart the SSH server to be able to access the system remotely using //ssh=somepassword//. Enabling such bootoptions is as simple as running:

  echo 'CUSTOM_BOOTOPTIONS="ssh=secretpasswd toram"' >> /etc/default/grml-rescueboot
  update-grub

===== Problems? =====

Are using your own hand-crafted GRUB configuration with a Grml ISO which used to work until and including Grml release 2011.05 but fails with 2011.12 and later ISOs? If so then very probably the [[http://grml.org/cheatcodes/|live-media-path=... bootoption]] is missing in the //linux// GRUB command line of your Grml ISO boot entry.

Please consider using grml-rescueboot instead. It does all the magic for you and uses the [[http://www.supergrubdisk.org/wiki/Loopback.cfg|loopback]] mechanism with "loopback loop ..." and "configfile /boot/grub/loopback.cfg", allowing to use the bootoptions as required by the according Grml ISO and therefore not breaking backwards compatibility.

If you really can't use grml-rescueboot for whatever reason (please [[http://grml.org/contact/|talk to us then]]!) have a look at the following configuration examples.

===== Configuration references ====

Those grub.cfg configuration entries are meant for reference purposes only - please use grml-rescueboot instead of manually creating such boot entries. Also be aware that the "insmod", "set root=..." and "search ..." options are system specific:

==== Sample GRUB2 configuration with loopback feature ====

  menuentry "Grml Rescue System (grml64-full_2012.05.iso)" {
          insmod part_msdos
          insmod ext2
          set root='(hd0,msdos1)'
          search --no-floppy --fs-uuid --set <snipped>
          iso_path="/boot/grml/grml64-full_2012.05.iso"
          export iso_path
          kernelopts=" ssh=password toram  "
          export kernelopts
          loopback loop "/boot/grml/grml64-full_2012.05.iso"
          set root=(loop)
          configfile /boot/grub/loopback.cfg
  }
  
==== Sample GRUB2 configuration without loopback feature ====

  menuentry "grml64-small 2012.05 (amd64)" {
          insmod part_msdos
          insmod ext2
          set root='(hd0,msdos1)'
          search --no-floppy --fs-uuid --set <snipped>
          echo 'Loading Grml kernel (amd64) ...'
          linux /boot/grml/vmlinuz boot=live noeject noprompt findiso=/boot/grml/grml64-small_2012.05.iso toram bootid=grml64small201205 ssh=secret live-media-path=/live/grml64-small/
          echo 'Loading Grml initrd (amd64) ...'
          initrd /boot/grml/initrd.img
  }

==== Sample GRUB2 configuration without loopback.cfg file ====

  menuentry "grml64-full 2012.05 (amd64)" {
          insmod part_msdos
          insmod ext2
          set root='(hd0,msdos1)'
          search --no-floppy --fs-uuid --set <snipped>
          iso_path="/boot/grml/grml64-full_2012.05.iso"
          export iso_path
          kernelopts=" ssh=password toram "
          export kernelopts
          loopback loop "/boot/grml/grml64-full_2012.05.iso"
          set root=(loop)
          source /boot/grub/grml64-full_default.cfg
  }

==== Sample GRUB1 configuration ====

  title           grml64-small 2012.05 (amd64)
  root            (hd0,1)
  kernel          /boot/grml/vmlinuz boot=live noeject noprompt findiso=/boot/grml/grml64-small_2012.05.iso toram bootid=grml64small201205 ssh=secret live-media-path=/live/grml64-small/
  initrd          /boot/grml/initrd.img


===== Important Bootoptions for Rescueboot and related Debugging =====

   * bootid=something: use specified argument as identifier for the ISO (by default corresponds to $GRML_FLAVOUR$VERSION without any special characters and whitespaces, like grml64small201205)
   * break=something: start debugshell during initramfs stage break=something (where valid arguments for something are: top, modules, premount, mount, mountroot, bottom, init)
   * debug=1: be more verbose about boot sequence execution
   * findiso=...:  look for the specified ISO file on all disks where it usually looks for the .squashfs file
   * ignore_bootid: disable boot ID verification
   * live-media-path=...: set path to the live filesystem on the medium (needs to be /live/$GRML_FLAVOUR/ by default, where $GRML_FLAVOUR is something like grml64-full, grml32-full, grml64-small,...)
   * noeject: do not //eject// ISO/CD after halt/reboot
   * noprompt: do not //prompt// to remove the ISO/CD when halting/rebooting the system
   * toram: copy the whole ISO to RAM and run from there
   * toram=filename.squashfs: copy only the specified file to RAM and run from there (example: toram=grml64-small.squashfs)

For further bootoptions and related documentation please visit http://grml.org/cheatcodes/