[CentOS] CentOS 5 grub boot problem

Thu Aug 6 20:59:48 UTC 2015
Gordon Messmer <gordon.messmer at gmail.com>

On 08/05/2015 10:23 AM, Chris Murphy wrote:
> Nothing about hd0 or hd1 gets baked into the bootloader code. It's an
> absolute reference to a physical drive at the moment in time the
> command is made.

Is that true?  If I have a system with two disks, where device.map 
labels one as hd0 and the other as hd1, and I swap those numbers, the 
resulting boot sector will differ by one bit.

My understanding was that those IDs are used to map to the BIOS disk 
ID.  Stage 2 will be read from the partition specified to the grub 
installer at installation, as in:
grub> install --stage2=/boot/grub/stage2 /grub/stage1 d 
(hd0,1)/grub/stage2 p (hd0,1)/grub/grub.conf

Stage 1 and 1.5 will, as far as I know, always be on (hd0), but stage2 
might not be.  If the BIOS device IDs specified in device.map weren't 
written into the boot loader, how else would it know where to look for them?