Xen users - Dec 2009 - PVGrub can''t find config file for domU on logical volume

After hours of googling and not really finding a definitive solution to my
problem, I''m a little stuck and would really appreciate some help from
others.

I have a CentOS 5.4 x86-64 server running Xen 3.3 from the gitco repos as
dom0.  On this I have created two logical volumes comprising 8GB for the
system disk (xvda) and 1.5GB for swap (xvdb).  I ran mkfs.ext3 and mkswap
on these to create the required filesystems and then I mounted the 8GB
volume and copied a system image onto it.  After creating the xen config
and starting it with pygrub the machine starts and runs without error - so
far, so good!

Now, If I shutdown the vm and change the config to use pvgrub and restart
I am stuck at a grub prompt.  If I manually tell it where to find the
config file (using the exact same path as in the ''extra'' line
in the domu
config) it pvgrub starts and everything then runs as expected.  Here is my
config:

--- snip ---
name = "pvgrubtestvm"
vcpus = 1
memory = 512
maxmem = 512

# pvgrub
kernel = "/usr/lib/xen/boot/pv-grub-x86_64.gz"
extra = "(hd0)/boot/grub/menu.lst"
#end pvgrub

dhcp = "dhcp"

disk = [ "phy:/dev/VolGroupVM/pvgrubtestvm,xvda1,w",
"phy:/dev/VolGroupVM/pvgrubtestvm-swap,xvda2,w" ]

vif = [
"mac=00:16:3e:00:00:09,ip=192.168.1.12,bridge=xenbr0,vifname=vifpvgrubtestvm"
]

on_poweroff = ''destroy''
on_reboot   = ''restart''
on_crash    = ''restart''
--- snip ---

Have I done something wrong? Is this an issue with pvgrub and logical
volumes - i.e. no partition table?


Many thanks,

Matt.


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Sorry to reply to my own post, but still not making any progress with
this.  Here''s my domU config file which is working with pyGrub.

#  -*- mode: python; -*-
name = "testvm"
vcpus = 1
memory = 1024
maxmem = 1024

# pygrub
bootloader = "/usr/bin/pygrub"
# end pygrub

# pvgrub
#kernel = "/usr/lib/xen/boot/pv-grub-x86_64.gz"
#extra = "(hd0,0)/boot/grub/menu.lst"
#end pvgrub

dhcp = "dhcp"

disk = [ "phy:/dev/VolGroupVM/testvm,xvda,w",
"phy:/dev/VolGroupVM/testvm-swap,xvdb,w" ]

vif = [
"mac=00:16:3e:00:00:12,ip=192.168.1.12,bridge=xenbr0,vifname=viftestvm"
]

on_poweroff = ''destroy''
on_reboot   = ''restart''
on_crash    = ''restart''

If I remove the pygrub bootloader line and un-comment the pvgrub entries I
always end up at the ''grubdom>'' prompt.  If I then enter
''configfile (hd0,0)/boot/grub/mennu.lst'' pvgrub works and I
can boot the domU
successfully.

I''d be really grateful if anyone can offer any advice?

Thanks in advance,

Matt.

On Sat, December 5, 2009 4:09 pm, Matthew Law wrote:
> After hours of googling and not really finding a definitive solution to my
> problem, I''m a little stuck and would really appreciate some help
from
> others.
>
> I have a CentOS 5.4 x86-64 server running Xen 3.3 from the gitco repos as
> dom0.  On this I have created two logical volumes comprising 8GB for the
> system disk (xvda) and 1.5GB for swap (xvdb).  I ran mkfs.ext3 and mkswap
> on these to create the required filesystems and then I mounted the 8GB
> volume and copied a system image onto it.  After creating the xen config
> and starting it with pygrub the machine starts and runs without error - so
> far, so good!
>
> Now, If I shutdown the vm and change the config to use pvgrub and restart
> I am stuck at a grub prompt.  If I manually tell it where to find the
> config file (using the exact same path as in the ''extra''
line in the domu
> config) it pvgrub starts and everything then runs as expected.  Here is my
> config:
>
> --- snip ---
> name = "pvgrubtestvm"
> vcpus = 1
> memory = 512
> maxmem = 512
>
> # pvgrub
> kernel = "/usr/lib/xen/boot/pv-grub-x86_64.gz"
> extra = "(hd0)/boot/grub/menu.lst"
> #end pvgrub
>
> dhcp = "dhcp"
>
> disk = [ "phy:/dev/VolGroupVM/pvgrubtestvm,xvda1,w",
> "phy:/dev/VolGroupVM/pvgrubtestvm-swap,xvda2,w" ]
>
> vif = [
>
"mac=00:16:3e:00:00:09,ip=192.168.1.12,bridge=xenbr0,vifname=vifpvgrubtestvm"
> ]
>
> on_poweroff = ''destroy''
> on_reboot   = ''restart''
> on_crash    = ''restart''
> --- snip ---
>
> Have I done something wrong? Is this an issue with pvgrub and logical
> volumes - i.e. no partition table?


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On Tue, Dec 8, 2009 at 7:52 PM, Matthew Law <matt@webcontracts.co.uk>
wrote:
> #kernel = "/usr/lib/xen/boot/pv-grub-x86_64.gz"
> #extra = "(hd0,0)/boot/grub/menu.lst"
This line is different from your previous post (hd0,0 vs hd0). Did you
try with the correct extra line? These lines wok for me

kernel="/usr/lib/xen/boot/pv-grub-x86_64.gz"
extra="(hd0,1)/boot/grub/menu.lst"

Also, if I''m not mistaken, pv-grub needs to be the same type as domU
kernel (i.e. both 32bit or both 64bit)

-- 
Fajar

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I tried with both extra lines.  The VM is debian lenny amd64 and was
installed into a single partition.

I''m going to try again from scratch using the debian netinstall image
direct from xm create.  Curious thing is that it works fine if I switch to
pygrub.  I really want to get pvgrub working for security reasons.

Thanks,

Matt.

On Wed, December 9, 2009 2:21 am, Fajar A. Nugraha
wrote:
> On Tue, Dec 8, 2009 at 7:52 PM, Matthew Law <matt@webcontracts.co.uk>
> wrote:
>> #kernel = "/usr/lib/xen/boot/pv-grub-x86_64.gz"
>> #extra = "(hd0,0)/boot/grub/menu.lst"
>
> This line is different from your previous post (hd0,0 vs hd0). Did you
> try with the correct extra line? These lines wok for me
>
> kernel="/usr/lib/xen/boot/pv-grub-x86_64.gz"
> extra="(hd0,1)/boot/grub/menu.lst"
>
> Also, if I''m not mistaken, pv-grub needs to be the same type as
domU
> kernel (i.e. both 32bit or both 64bit)
>
> --
> Fajar

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