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

[Richie <listmail@triad.rr.com>]

I like the idea myself and I haven't seen anything in the wiki's other 
than manual creation steps.

Just an opinion here, but why not use "dummy=dummy" as opposed to first 
parameter duplication?  My understanding is that dummy is used to avoid 
this same bug.  Either way we it avoids having to hardcode root= into 
the kernel cmdline .config parameter :)  I don't know if parameter 
duplication would break things when the bug is fixed or not, but the 
dummy parameter shouldn't.  I also think it might be viewed as something 
more familiar, perhaps self explanatory, whereas the parameter 
duplication may cause confusion.

I skimmed the code and have not tested it.  I don't see that it is 
specifically trying to ensure that the kernel is Xenlinux or pvops...  
Not that I know of a proper way to do such or if its even pratical.  
Aren't most kernels now pvops (thus bootable under xen) but not 
necessarily dom0 capable?  I think a spin on this would be if one wanted 
to limit the Xen entries to kernels with "xen" (ie. --append-to-version) 
in the name.  Perhaps the code would change as follows?

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



Bruce Edge wrote:
> 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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