Xen project Mailing List

Thanks

-Bruce

On Tue, May 18, 2010 at 5:24 PM, Richie <listmail@xxxxxxxxxxxx> wrote:

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