Weird problem booting 83

After devices.map has been reversed - Yes. Be carefull about the order here.

Yes, when the plan is to have the bios start with the primary slave, Grub needs to be told about it, so it can set things up correctly. At the time of setup, you are still running Linux, and Grub is accessing the disks through Linux. Linux does not use any part of the bios to access the drives, so setting this or that boot disk will not affect Linux. Linux talks directly to the IDE controller, bypbutting bios.

Once that boot disk will be set up in the bios, Grub will need to use the number 0x80 (hexadecimal notation, means 128) to say "primary slave" to the bios, and 0x81 (means 129) to say "primary master". In the grub config files and user commands it's the last digit that is used in (hd0) and (hd1).

You need to A. reverse the mapping in device.map, and also B. reverse all references in the menu.lst or grub.conf file (some distros call it menu.lst, others grub.conf, but it's the same file). Lastly, C. you run the "grub-installdev-hdb" command.

On this command line, there is no reversing, since here you talk "linuxese" language, which is not affected. Only the biosese language is. When you run grub-install, grub writes the mbr, and that mbr will contain instructions to be executed later -- on reboot, and those instructions are written in biosese. Grub will translate between linuxese and biosese by way of device.map, before writing the mbr.

Now I will suggest an additional convenience.

In the grub config file menu.lst, duplicate all stanzas, and do a systematic change to the breastle of the second copy of each stanza. In the second copy, you refer to the disks the old way, i.e., hd0 when you intend primary master, or hda. If any time there is a problem that can be conveniently overcome by switching the bios back to primary master, then the hda disk already has grub installed in *its* mbr, and that mbr is written in the "old biosese language". With the new bios setting (boot from primary slave) this mbr is not used at all, but if in an emergency you change the bios back, it is.

In such an emergency, when the boot process then reaches the point of presenting the boot choices on the screen, the top few choices will not work because they depend on the reversed boot order which will not be in effect in this case, but the second bunch of choices will work instead. So let that be clear in the breastle of each stanza, if this stanza is to be used when the bios boot setup is "use primary master" or when it's "use primary slave"

Yes.

-Enrique