On Friday 26 November 2004 04:23, John DeDourek wrote: > Duncan Lithgow wrote: > > I'd better mark this thread solved... > > > >> That suggests to me that it's probably safest to put grub in hda1 or > >> so, and mark that partition bootable. > > > > That's the default isn't it? Paul said that MBR is in the first part of > > hda1 - and because I'm also running windows it _has_ to be marked > > bootable (or somewhere before 1024 has to) > > > > Thanks again for the help > > > > Duncan > > Just a clarification. There is a boot block at the beginning of > disk (BEFORE the first partition) and a boot block at the beginning > of every partition. "MBR" refers to the boot block at the beginning > of the disk. R==record. The first secor, 512 bytes. The code I was inspecting fits into onse sector. > > Now, something that I'm less sure of. If you put grub into the MBR > (means code in the MBR and the 1.5 stage in the following sectors) > then it can boot any partition, marked "bootable" or not. True. > > If you install grub in some other partition (technically the boot > block of that partition with stage 1.5 in the following sectors) > then the code executed first will be whatever is installed in MBR. > If that code is installed by windows, then I believe that it loads > the code from the boot block of whichever partition is marked > bootable. That would have to be the partition with grub in the > boot block if you want to bring up grub. The code in the MBR finds the first "bootable" partition. This is the coe Windows installs to clobber Grub. Back when I used to (sometimes) use Windows NT and (mostly) OS/2 Microsoft documented how to make "the other OS bootable." One went into Disk Mmngler and marked the other partition bootable. Normally that other parition contained OS2/ Boot Manager. > > Now if you want that grub to chain load windows, I think (but am > not sure) that you need to change which partition is bootable > (using grub commands in grub.conf) to mark the windows partition > bootable before you chain to its boot loader. There was no mucking around needed with Boot Manager. Whether I booted OS/2, NT or Linux with it, on the next reboot Boot Manager got started. Installing Windows NT after OS/2 caused NT to boot in place of Boot Manager, but that was easily overcome as I've already mentioned. > Perhaps someone more knowledgeable about grub could confirm or > correct this latter comment. -- Cheers John
