[ltp] Re: A question about USB storage and ehci_hcd

[Stefan Monnier]

> No.  GRUB has to use real-mode BIOS functions to address disks for
> obvious reasons, and can't use labels or UUIDs.  The calls GRUB has to
> make go by number--first disk is 0x80, second disk is 0x81, etc.  And
> the *BIOS* decides which disk is first.  This can lead to hassles.  The
> BIOS might decide that SATA disk 0 is (hd2) when you boot from an IDE 
> CD-R*, and might decide that it's (hd0) when you boot from the SATA disk.
> For USB devices, anything might happen.

I have a "Debian on a USB stick" and I don't have too many problems with
it so far:
- the drive from which Grub was loaded seems to always be hd0, so I can
  just use hd0 when specifying where the kernel and initrd files are to
  be found.
- w.r.t telling the kernel where to fin the root partition, I use udev
  (from within the initrd) so I can use any of the previously mentioned
  techniques (LABELs, UUID, ...).


-- Stefan