On Tuesday 17 June 2008, Mikkel L. Ellertson wrote: >Gene Heskett wrote: >> On Tuesday 17 June 2008, M A Young wrote: >>> On Tue, 17 Jun 2008, Maurizio Marini wrote: >>>> I would advice any list member that it is in the wild a issue regarding >>>> grub and mbr. >>> >>> I don't know if this is relevant, but F8 grub (unless the latest update >>> has been written to the boot sector) can't cope with filesystems created >>> on F9 because of the inode size change. So it is definitely a good idea >>> to upgrade grub if you are upgrading. >>> >>> Michael Young >> >> Which may be a good idea, Michael, but does this require the silent >> re-writing of the mbr to accomplish this? For existing, already setup and >> working drives, I don't think so. > >Yes, it does require re-writing the MBR. This is because Grub stage >1 is in the MBR, and it needs to know where on the disk Grub stage >1.5 is. When you upgrade Grub, the location changes. Stage 1.5 is >the part of Grub that know how to read file systems, and can then >load the rest of Grub. Remember, all stage 1 can do is load a chunk >of code from a specific location on the disk, and the location is >part of the code stored in the MBR when you install/upgrade Grub. >Why would you think that upgrading the boot loader would not >re-write the MBR? > >Mikkel Well, considering this machine has to have a customized device.map, one which grub will cheerfully wipe, and has once already, replacing it with its own version, effectively swapping /sda, /sdb and /sdc around, and totally preventing a boot cuz then the bios cannot see the correct drive. This bios doesn't know a thing about how to boot from a sata drive on an accessory controller. You can call it /dev/sda all you want once linux is running I guess, but if the bios can't see it to boot from it, which it cannot, well, you get the picture I hope. So yes, if it silently rewrote the mbr, it will just as silently rewrite the device.map, and this list will, whenever I do manage to get it booted again, hear from one very unhappy camper. So thanks for the warning, I'm off to dd a backup of the mbr and /boot/grub to a usb key and to what is now /dev/sdc in hopes I can recover from such a boneheaded 'upgrade'. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) I was at this restaurant. The sign said "Breakfast Anytime." So I ordered French Toast in the Rennaissance. -- Steven Wright -- fedora-list mailing list fedora-list@xxxxxxxxxx To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list
