Boot problems afther reinstall windows
Alex de Kruijff
freebsd at akruijff.dds.nl
Thu Mar 17 23:11:01 PST 2005
On Tue, Mar 15, 2005 at 07:05:58PM -0500, Jerry McAllister wrote:
> > > > timeout=10
> > > > default=c:\freebsd.bin
> > > > [operating systems]
> > > > multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Microsoft Windows XP
> > > > Professional" /fastdetect /NoExecute=OptIn
> > > > c:\freebsd.bin="FreeBSD 5"
> > > >
> > > > This works for me. I still wonder why the stuff below didn't work. In
> > > > the past I would do this with /stand/sysinstall. But I don't dare to do
> > > > this with FreeBSD 5 because of drive geometric warnings.
> > > >
> > >
> > > Remember there are two boot blocks, so to speak.
> > > There is the MBR that lets you choose which slice to boot. There is
> > > only one of those per disk and it lives in "sector 0" of the disk.
> > > The MBR generally has a standard calling sequence (that the Bios calls)
> > > and sets things up to a fairly standard condition and looks for
> > > standard appearing boot sectors in slices and makes a standard
> > > call to the selected slice's boot sector. Almost any MBR that
> > > knows how to recognize a standard boot sector in a slice and lets
> > > you choose between them if there are more than one can be used
> > > interchangeably.
> > >
> > > Then there is the boot block with the actual boot loader that starts
> > > pulling the OS from the bootable partition. On a multi boot disk
> > > there are several - one per each bootable slice and they live in the
> > > boot sector of each slice. Those are specific to the OS they are
> > > booting. Though their calling sequence is standard, what they have
> > > to do to load and start their own OS is not.
> > Is it posible to boot one OS if you only have the MBR?
> No, you need the boot sector. If you have only that in the first
> location, you can boot without an full MBR, I think, but not without
> the boot sector that the MBR loads and jumps to.
But its not posible to put the code of the boot sector in the MBR
place? (i.e. doesn't fit)
> > > I am guessing that you managed to overwrite or damage the MS slice'
> > > boot sector while you were doing things, or didn't get it written
> > > to the slice properly when you reloaded or something like that.
> > > Even though you put the MBR back with FreeBSD's fdisk, did you
> > > also make sure that the MS slice had its own boot loader? Anyway
> > > you did when you put the MS boot loader back. So it works now.
I think the anwser to you question should be no. It booted before I put
the MBR back.
> > The previous time I first installed windows and then FreeBSD 5. The
> > difference this time is that I didn't use /stand/sysinstall. This
> > because I would get into serious troubel. (I never found out how to
> > force the right geometry) So I was thinking maybe sysinstall does
> > something (like copy the MBR to the second boot location) that I didn't
> > do manualy.
> I think you are using MBR for boot sector.
I think you mean by word and not on disk.
> The MBR is what goes
> in sector 0 of the disk itself. The boot sector/record/block
> goes in the first sector of the slice. The MBR lets you pick the
> slice you want to boot and then loads its boot sector/block/record and
> jumps to it in a standard location.
MBR = /boot/boot0 (a copy of it)
boot sector = /boot/boot1
What I was thinking is:
Now windows overwrites the MBR. And I was thinking it would put the boot
sector in the place of MBR. If this is the case then windows looses the
capability to boot.
Please copy the original recipients, otherwise I may not read your reply.
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