Chainloading GRUB2 from Lilo

Chainloading GRUB2 from Lilo

[Tim Booth]

Hi All,

Sorry to clog up the developer list with my questions but I've scoured
the documentation and not found an answer.

I've hit this known problem:
http://sourceforge.net/apps/mediawiki/bootinfoscript/index.php?title=Boot_Problems:Windows_Writes_To_MBR

Where broken software on Windows is clobbering GRUB2.  Modifying the
corporate Windows installation is not an option, so I'm trying to use
Lilo in the MBR and immediately chainload Grub.

Now I could install Grub into the (Ubuntu) Linux partition, but it seems
rather simpler to just ask Lilo to chainload core.img.  As far as I can
tell, the only way to do this is to use lnxboot.img, telling lilo that
core.img is an initrd. - ie. like this:

---my /etc/lilo.conf---
# Very basic LILO chainloader config
boot = /dev/sda
lba32
default = chainload_grub2
timeout = 0

image = /boot/grub/lnxboot.img 
  append = "prefix=(hd0,5)/boot/grub"
  root=/dev/hda5
  initrd = /boot/grub/core.img
  label = chainload_grub2
---end---

But when Grub loads the prefix is set to (hd0,1)/boot/grub and I just
get a recovery prompt and have to do:

set prefix=(hd0,5)/boot/grub
insmod normal
normal

So, is there any way to get the correct prefix passed through?  I know
there are other ways to attack this problem, but as the fix needs to be
maintained on many machines I'm looking for something as simple as
possible, and this is the simplest I can come up with, so I thought I'd
ask this list before abandoning the idea completely.

Cheers,

TIM

-- 
To Err is human.
To Arrr is Pirate!

Re: Chainloading GRUB2 from Lilo

[Vladimir 'φ-coder/phcoder' Serbinenko]

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Tim Booth wrote:
> Hi All,
>
> Sorry to clog up the developer list with my questions but I've scoured
> the documentation and not found an answer.
>
> I've hit this known problem:
> http://sourceforge.net/apps/mediawiki/bootinfoscript/index.php?title=Boot_Problems:Windows_Writes_To_MBR
>
> Where broken software on Windows is clobbering GRUB2.  Modifying the
> corporate Windows installation is not an option, so I'm trying to use
> Lilo in the MBR and immediately chainload Grub.
>   
Asking such a lilo question on GRUB list is annoying, especially that
it's not a real solution.
Could you try installing grub to mbr, then dump the MBR gap with
dd if=/dev/sda of=before.bin count=64
<let windows do its anti-competitive job>
dd if=/dev/sda of=after.bin count=64
Then send both files to me? Or just say which sectors are modified.
It was reported that only sectore number 32 is modified. If it's
confirmed we can avoid using it unless we need the whole MBR gap (very
uncommon)

> Now I could install Grub into the (Ubuntu) Linux partition, but it seems
> rather simpler to just ask Lilo to chainload core.img.  As far as I can
> tell, the only way to do this is to use lnxboot.img, telling lilo that
> core.img is an initrd. - ie. like this:
>
> ---my /etc/lilo.conf---
> # Very basic LILO chainloader config
> boot = /dev/sda
> lba32
> default = chainload_grub2
> timeout = 0
>
> image = /boot/grub/lnxboot.img 
>   append = "prefix=(hd0,5)/boot/grub"
>   root=/dev/hda5
>   initrd = /boot/grub/core.img
>   label = chainload_grub2
> ---end---
>
> But when Grub loads the prefix is set to (hd0,1)/boot/grub and I just
> get a recovery prompt and have to do:
>
> set prefix=(hd0,5)/boot/grub
> insmod normal
> normal
>
> So, is there any way to get the correct prefix passed through?  I know
> there are other ways to attack this problem, but as the fix needs to be
> maintained on many machines I'm looking for something as simple as
> possible, and this is the simplest I can come up with, so I thought I'd
> ask this list before abandoning the idea completely.
>
> Cheers,
>
> TIM
>
>   


-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko



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Re: Grub data clobbered by Novell ZENworks (was: Chainloading GRUB2 from Lilo)

[Tim Booth]

Hi Vladimir,

Thanks for your response.  I think my original question was more to do
with using lnxboot.img than with Lilo per se, but I totally agree that
my "solution" stinks.  If there is an easy workaround within Grub then
that would save a lot of hassle.

Following your suggestion I made the two files and a quick hexdump+diff
reveals that sector 6 has been overwritten.  This begins with the
characters ZISD and thus led me to the good explanation here:

http://www.novell.com/communities/node/5839/grub-and-zisd

I have an older version than documented above, so moving the sector
doesn't help and sector 6 just gets clobbered every time.

The fix suggested on the site shifts up 13 sectors to sector 17.  This
suggests that newer versions of ZISD use a lot more space and just may
not fit alongside Grub2 at all, but I don't have such a version to try.

In my case there is only one sector changed, but I have no way to stop
that particular sector being clobbered.  Is there a way to make Grub
skip that sector?

Cheers,

TIM

On Fri, 2010-04-02 at 21:53 +0200, Vladimir 'φ-coder/phcoder' Serbinenko
wrote: 
> Tim Booth wrote:
> > Hi All,
> >
> > Sorry to clog up the developer list with my questions but I've scoured
> > the documentation and not found an answer.
> >
> > I've hit this known problem:
> > http://sourceforge.net/apps/mediawiki/bootinfoscript/index.php?title=Boot_Problems:Windows_Writes_To_MBR
> >
> > Where broken software on Windows is clobbering GRUB2.  Modifying the
> > corporate Windows installation is not an option, so I'm trying to use
> > Lilo in the MBR and immediately chainload Grub.
> >   
> Asking such a lilo question on GRUB list is annoying, especially that
> it's not a real solution.
> Could you try installing grub to mbr, then dump the MBR gap with
> dd if=/dev/sda of=before.bin count=64
> <let windows do its anti-competitive job>
> dd if=/dev/sda of=after.bin count=64
> Then send both files to me? Or just say which sectors are modified.
> It was reported that only sectore number 32 is modified. If it's
> confirmed we can avoid using it unless we need the whole MBR gap (very
> uncommon)
> 
> > Now I could install Grub into the (Ubuntu) Linux partition, but it seems
> > rather simpler to just ask Lilo to chainload core.img.  As far as I can
> > tell, the only way to do this is to use lnxboot.img, telling lilo that
> > core.img is an initrd. - ie. like this:
> >
> > ---my /etc/lilo.conf---
> > # Very basic LILO chainloader config
> > boot = /dev/sda
> > lba32
> > default = chainload_grub2
> > timeout = 0
> >
> > image = /boot/grub/lnxboot.img 
> >   append = "prefix=(hd0,5)/boot/grub"
> >   root=/dev/hda5
> >   initrd = /boot/grub/core.img
> >   label = chainload_grub2
> > ---end---
> >
> > But when Grub loads the prefix is set to (hd0,1)/boot/grub and I just
> > get a recovery prompt and have to do:
> >
> > set prefix=(hd0,5)/boot/grub
> > insmod normal
> > normal
> >
> > So, is there any way to get the correct prefix passed through?  I know
> > there are other ways to attack this problem, but as the fix needs to be
> > maintained on many machines I'm looking for something as simple as
> > possible, and this is the simplest I can come up with, so I thought I'd
> > ask this list before abandoning the idea completely.
> >
> > Cheers,
> >
> > TIM
> >
> >   
> 
> 
> _______________________________________________
> Grub-devel mailing list
> Grub-devel@gnu.org
> http://lists.gnu.org/mailman/listinfo/grub-devel
-- 
To Err is human.
To Arrr is Pirate!