/etc/grub.d/09-xen for generating grub.cfg for hypervisor boot entries.

[Bruce Edge <bruce.edge@gmail.com>]

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If this has already been done, please forgive me. However, if not, I'd like
to submit this as a mechanism for generating a bootable grub2 stanza for
hypervisors.

As the /etc/grub.d/* files rely on defaults in /etc/default/grub, I added
the following Xen specific variable:

GRUB_CMDLINE_XEN_DEFAULT="console=com1 115200,8n1 dom0_mem=512M
dom0_max_vcpus=1 dom0_vcpus_pin=true iommu=1,passthrough,no-intremap
loglvl=all loglvl_guest=all loglevl=10 debug acpi=force apic=on
apic_verbosity=verbose numa=on"

The script itself is a hacked version of the10-linux that comes with grub2.
This is 09-xen so it places it's boot entries ahead of the non-xen entries.
The resulting grub.cfg entry looks like:

### BEGIN /etc/grub.d/09_xen ###
  insmod lvm
  set root=(system-dom0_0)
menuentry "Xen osa-dom0 6.0.13-05, linux 2.6.32.12" {
        multiboot /boot/xen.gz /boot/xen.gz console=com1 115200,8n1
dom0_mem=512M dom0_max_vcpus=1 dom0_vcpus_pin=true
iommu=1,passthrough,no-intremap loglvl=all loglvl_guest=all loglevl=10 debug
acpi=force apic=on apic_verbosity=verbose numa=on
        module /boot/vmlinuz-2.6.32.12 /boot/vmlinuz-2.6.32.12
root=UUID=a3764d7d-6292-4f08-8ece-480e54c77229  ro earlyprintk=xen
loglevel=10 debug acpi=force console=hvc0,115200n8
        module /boot/initrd.img-2.6.32.12 /boot/initrd.img-2.6.32.12
}
### END /etc/grub.d/09_xen ###

Note the duplication of the first params. I believe there's a bug that drops
the 1st param so this could be changed later.

#! /bin/sh -e

prefix=/usr
exec_prefix=${prefix}
libdir=${exec_prefix}/lib
. ${libdir}/grub/update-grub_lib

if [ "x${GRUB_DISTRIBUTOR}" = "x" ] ; then
  OS=GNU/Linux
else
  OS="${GRUB_DISTRIBUTOR}"
fi

# Source grub defaults
. /etc/default/grub

# loop-AES arranges things so that /dev/loop/X can be our root device, but
# the initrds that Linux uses don't like that.
case ${GRUB_DEVICE} in
  /dev/loop/*|/dev/loop[0-9])
    GRUB_DEVICE=`losetup ${GRUB_DEVICE} | sed -e
"s/^[^(]*(\([^)]\+\)).*/\1/"`
  ;;
esac

if [ "x${GRUB_DEVICE_UUID}" = "x" ] || [ "x${GRUB_DISABLE_LINUX_UUID}" =
"xtrue" ] \
    || ! test -e "/dev/disk/by-uuid/${GRUB_DEVICE_UUID}" ; then
  LINUX_ROOT_DEVICE=${GRUB_DEVICE}
else
  LINUX_ROOT_DEVICE=UUID=${GRUB_DEVICE_UUID}
fi

test_gt ()
{
  local a=`echo $1 | sed -e
"s,.*/vmlinu[zx]-,,g;s/[._-]\(pre\|rc\|test\|git\|old\)/~\1/g"`
  local b=`echo $2 | sed -e
"s,.*/vmlinu[zx]-,,g;s/[._-]\(pre\|rc\|test\|git\|old\)/~\1/g"`
  if [ "x$b" = "x" ] ; then
    return 0
  fi
  dpkg --compare-versions "$a" gt "$b"
  return $?
}

find_latest ()
{
  local a=""
  for i in $@ ; do
    if test_gt "$i" "$a" ; then
      a="$i"
    fi
  done
  echo "$a"
}

list=`for i in /boot/vmlinu[xz]-* /vmlinu[xz]-* ; do
        if grub_file_is_not_garbage "$i" ; then echo -n "$i " ; fi
      done`

while [ "x$list" != "x" ] ; do
  linux=`find_latest $list`
  echo "Found linux image: $linux" >&2
  basename=`basename $linux`
  dirname=`dirname $linux`
  rel_dirname=`make_system_path_relative_to_its_root $dirname`
  version=`echo $basename | sed -e "s,^[^0-9]*-,,g"`
  alt_version=`echo $version | sed -e "s,\.old$,,g"`
  linux_root_device_thisversion="${LINUX_ROOT_DEVICE}"

  initrd=
  for i in "initrd.img-${version}" "initrd-${version}.img" \
           "initrd.img-${alt_version}" "initrd-${alt_version}.img"; do
    if test -e "${dirname}/${i}" ; then
      initrd="$i"
      break
    fi
  done
  if test -n "${initrd}" ; then
    echo "Found initrd image: ${dirname}/${initrd}" >&2
  else
    # "UUID=" magic is parsed by initrds.  Since there's no initrd, it can't
work here.
    linux_root_device_thisversion=${GRUB_DEVICE}
  fi

  cat << EOF
  insmod lvm
  set root=(system-dom0_0)
menuentry "Xen ${OS}, linux ${version}" {
        multiboot /boot/xen.gz /boot/xen.gz $GRUB_CMDLINE_XEN_DEFAULT
        module ${rel_dirname}/${basename} ${rel_dirname}/${basename}
root=${linux_root_device_thisversion} $GRUB_CMDLINE_LINUX_DEFAULT
EOF
  if test -n "${initrd}" ; then
    cat << EOF
        module ${rel_dirname}/${initrd} ${rel_dirname}/${initrd}
EOF
  fi
  cat << EOF
}
EOF

  list=`echo $list | tr ' ' '\n' | grep -vx $linux | tr '\n' ' '`
done


-Bruce

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