during boot, how does grub decide from which disk to load the grub.config?

[John Lumby]

typically when I set up a new disk, I do it like this:
.  existing disk with already-installed grub and root/boot ptns in hd0
.  new empty disk in hd1
.  create ptns on new disk and copy files to it
.  reboot hd0 and in grub, bring up the command line:
.    root (hd0,1)
.    setup (hd1)
This works but when I switch the disks and boot the new one,
it picks up the grub.config from the old one (the one that used to be hd0 
and is now hd1)
instead of from itself.     If I want to fix this, I then have to re-setup:  
 with new disk in hd0:
.    root (hd0,1)
.    setup (hd0)
This quirk seems to be referred to in
http://lists.gnu.org/archive/html/bug-grub/2000-09/msg00041.html
but I don't see what I should do (if anything) to make the first setup 
specify to refer to itself for future boots.

Would this do what I want (I would try it but don't have an empty disk to 
experiment with any more! )
.  existing disk with already-installed grub and root/boot ptns in hd0
.  new empty disk in hd1
.  create ptns on new disk and copy files to it
.  reboot hd0 and in grub, bring up the command line:
.    root (hd1,1)
.    setup (hd1)

Or should I be using the install sub-command rather than setup?

What actually determines from which hd* grub will load its grub.config?

John