On Sat, 2010-11-20 at 18:48 +0100, Daniel Pocock wrote:
> Ultimately, I believe Debian 5 (lenny) is still a supported option for
> people after the release of squeeze and up to the release date of
> Debian 7.
oldstable is generally supported for a little while after a new stable
release but it is a very much more frozen/conservative style support
even than stable, which is in itself quite conservative in what it takes
in updates. The bar for taking fixes into oldstable is high and is
focused on security fixes and super-critical issues etc.
> I might be willing to have a deeper look at the problem and see if I can
> improve the error messages, etc. However, if such a patch was produced,
> would it be adopted in lenny so that users who keep their systems up to
> date will be able to run this without effort?
Ultimately it would be up to the Xen package maintainer and subsequently
the stable release maintainers. I think the first step towards
convincing the Xen maintainer to take patches of this type would be
resolving the issue upstream.
I guess it would depend on how large/intrusive the patch ended up being
so its hard to say up front but personally I have my doubts that a fix
for the pygrub logging crapness issue would make it into Lenny at this
stage of Lenny's life.
However it is still valuable to fix these things either upstream or in
the Debian unstable packaging, even if they cannot go into the current
stable version, so that a future version of Debian can benefit from the
fixes.
> Is it feasible to include some kind of grub1-emulator package in
> squeeze, something that lets the squeeze system use grub2, but creating
> a valid menu.lst file for pygrub to find? I think this would provide
> the smoothest experience for the users who just want the lenny/squeeze
> dom0/domU thing to work.
I'm sure it would be technically possible but I'm not sure if the grub2
package maintainers would go for it, it would be a largish maintenance
burden for them which is needed only to support Xen.
If you can make the preseeding on the installer command line thing work
I would certainly be open to taking a patch to the Squeeze xm-debian.cfg
example file to detect a Lenny dom0 somehow and automatically append the
necessary runes.
> > You should be able to cause Squeeze to install grub1 (aka grub-legacy),
> > although it may be an expert mode installation option only which is less
> > convenient.
> >
> I can chroot the domU and get grub-legacy, but I'm hesitant to run any
> grub commands within the chroot out of concern that it will impact the
> dom0's MBR
I think it won't but I certainly understand the concern!
> >> Root causes:
> >> - Squeeze installs grub 2, which doesn't have any /boot/grub/menu.lst
> >> - pygrub can't seem to identify the boot partition in the MBR created by
> >> the installer
> >>
> >
> > pygrub doesn't care about the contents of the MBR as such, it just
> > parses the partition table and AFAIK pygrub does know how to find the
> > bootable partition. There should be nothing Squeeze or grub[12] specific
> > about this aspect of things,
> >
> I tried invoking the pygrub script directly against the LV and the
> partition within the LV:
>
> /usr/lib/xen-3.2-1/bin/pygrub -i /dev/mapper/vg00-squeeze1_disk0
> gives an error
>
> kpartx -a /dev/mapper/vg00-squeeze1_disk0 &&
> /usr/lib/xen-3.2-1/bin/pygrub -i /dev/mapper/vg00-squeeze1_disk0p1
> finds the menu.lst I created manually, and displays the menu
This manually created menu.lst was present in the pygrub example just
above too?
> If it is not an MBR issue on squeeze1_disk0, why doesn't pygrub find the
> boot partition and menu.lst?
A bug in pygrub rather than anything to do with the content of the
MBR/partition-table. I think we can trust that the Squeeze installer is
creating a partition table which a physical system would be happy to
boot correctly (otherwise there would be a lot of noise being made!) and
pygrub should/must not need anything more special.
I'm pretty certain this works in more recent pygrubs although I don't
see an obvious smoking gun in the diff between the two. It might be
interesting to instrument up the various probing functions of pygrub and
see why it is rejecting the bootable partition.
I don't have any Lenny domain 0 systems handy but I'm going to install a
Squeeze VM on the system I do have and try running the Lenny pygrub on
it to see if I can reproduce the issue. Your Squeeze VM is a pretty
straight forward "mostly pressed enter" installation, right?
> Does grub2 do anything else to the partition table?
I don't know, but partitioning is more a function of the installer (or
the advanced user if they go manual) than grub so I'd expect not.
> If I run fdisk on that partition table, it complains
> about cylinder boundaries:
I don't know if that indicates a real problem. Cylinder boundaries is a
bit of an obsolete concept for an LVM volume anyway.
Ian.
>
> fdisk /dev/mapper/vg00-squeeze1_disk0
>
> Command (m for help): p
>
> Disk /dev/mapper/vg00-squeeze1_disk0: 6979 MB, 6979321856 bytes
> 255 heads, 63 sectors/track, 848 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
> Disk identifier: 0x0000373f
>
> Device Boot Start End
> Blocks Id System
> /dev/mapper/vg00-squeeze1_disk0p1 * 1 32
> 248832 83 Linux
> Partition 1 does not end on cylinder boundary.
> /dev/mapper/vg00-squeeze1_disk0p2 32 849
> 6563841 5 Extended
> Partition 2 does not end on cylinder boundary.
> /dev/mapper/vg00-squeeze1_disk0p5 32 849
> 6563840 8e Linux LVM
>
>
>
>
--
Ian Campbell
Current Noise: Razor Of Occam - Bite Of Dogmata
"What I've done, of course, is total garbage."
-- R. Willard, Pure Math 430a
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