Date: Fri, 18 Mar 2005 08:09:56 +0100 From: Alex de Kruijff <freebsd@akruijff.dds.nl> To: Jerry McAllister <jerrymc@clunix.cl.msu.edu> Cc: Jason Henson <jason@ec.rr.com> Subject: Re: Boot problems afther reinstall windows Message-ID: <20050318070956.GA1105@Alex.lan> In-Reply-To: <200503160005.j2G05xY24480@clunix.cl.msu.edu> References: <20050315234343.GH794@Alex.lan> <200503160005.j2G05xY24480@clunix.cl.msu.edu>
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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. -- Alex Please copy the original recipients, otherwise I may not read your reply. WWW: http://www.kruijff.org/alex/FreeBSD/
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