Fwd: Re: MBR was destroyed
saulius2 at ar.fi.lt
Tue Nov 22 05:30:02 CST 2005
* On Mon, 21 Nov 2005 wino at piments.com wrote:
> * On Mon, 21 Nov 2005 15:05:28 +0100, seorge <seorge at gmail.com> wrote:
> > Please tell me, what exact information should I provide the developers
> > with the experiment described below.
> You may run dd command to retrieve MBR at every moment, calculate it's
> checksum and see whether it differs or not.
BTW, after the Alexandre reply about volume changing I guess this possibly
should be partition boot sector that is destroyed, not a MBR.
Seorge, can you explain, how did you exactly restored MBR using GRUB,
> fiddle with wine, one step at a time , running the following check at
> each step, keeping notes on what is done each time.
> dd if=/dev/hda of=/boot/hda.wine1.mbr bs=512 count=1
> diff /tmp/*0.mbr /tmp/*1.mbr
BTW, I think only the text files should be diffed (and -u flag makes
output very understandable for me):
cat /tmp/hda.wine0.mbr | od -t x1 > /tmp/0.mbr.txt
cat /boot/hda.wine1.mbr | od -t x1 > /tmp/1.mbr.txt
diff -u /tmp/0.mbr.txt /tmp/1.mbr.txt
That would show how much different MBRs are. And if they don't start to
differ ever, maybe we should refer to appropriate partition (system from
which cannot boot later)? Then "hda" string should be replaced with a
partition name - "hda1" or so.
But comparing hexadecimal dumps should be the only and the final step, as
it says not only whether sectors are different, but also how much they
differ. Which isn't interesting at start of hunting.
> The main thing is to establish exactly what you did, it may not be quite
> where you thought and it will make finding the offending code a lot
> quicker if it is precisely linked to one event.
It would be interesting to know, whether latest CVS helps, as Alexandre
has put some fixes in regarding this issue, I guess:
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