MBR blown away
jerrymc at clunix.cl.msu.edu
Sat Feb 11 20:05:23 PST 2006
> --- Jerry McAllister <jerrymc at clunix.cl.msu.edu> wrote:
> > >
> > > I need help.
> > >
> > > I added a slice to a single hard drive dual-boot (windows) system and
> > now
> > > I guess that scrambled my MBR. I get three options from the FreeBSD
> > (5.4)
> > > boot manager:
> > >
> > > 1. DOS
> > > 2. FreeBSD
> > > 3. FreeBSD
> > >
> > > I can boot to FreeBSD (the new slice is fine) by choosing option 3 but
> > the
> > > windows/dos option is fried.
> > The MBR itself looks OK. According to that piece of menu you posted,
> > you
> > just added another bootable slice. So, there are now two bootable
> > FreeBSD
> > slices and one bootable Microsloth slice.
> The thing is, I never ran the boot manager after changing the (existing
> FAT32) windows partition to a FreeBSD slice. The boot manager config
> would be the same and so it continues to list DOS as a bootable partition
> when it is/may not.
> > Are you saying that the MS slice will no longer boot if you select '1'
> > from
> > the menu? If that is the case, it is not the MBR that was messed up.
> Correct, I chose '1' and then the system hangs (no messages/errors).
> > It is something in the MS slice - probably their boot sector. I don't
> > even
> > pretend to know how MS sets up theirs if it is any different from
> > FreeBSD.
> > But, the MBR is doing what it is supposed to do. It discovers all the
> > bootable slices and makes a menu and transfers control to the selected
> > slice. What happens after that is not the problem of the MBR.
> I don't think the MBR discovers anything. It is pre-defined to just point
> to the bootable partitions. And it is the boot manager that creates the
> menu probably by looking at the MBR. AFAIK, the boot manager must be
> explicitly instructed to do that (sysintall must provide this instruction
> during a full install).
> > Did you use some utility to shrink the original two slices to fit in
> > the new one? Or was there already unused space (previously unallocated)
> > that you were using?
> I simply converted a 6GB FAT32 partition into a UFS2 slice (chopped into
> three 2GB partitions).
Well, I still am guessing the problem lies in individual slices' boot
sectors and not the MBR. just try and set the bootable flags in the
slices the way you think they should be and see what happens.
> Find your next car at http://autos.yahoo.ca
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