Haiku assumes wrong boot drive when booting from USB

[luroh]

(spinoff from #3532)
When booting from a USB stick, Haiku picks up the presence of an old deleted Haiku partition on my SATA drive and sets it as /boot.

1. Booting starts from a USB stick.
   
2. At some point during boot, the system detects an old deleted Haiku partition on the SATA drive and decides to set it as /boot. This explains why the system loads slowly during bootsplash but fast once it reaches Desktop.
   
3. Fully booted, the USB stick is now /Haiku1.

To avoid 2 from happening, I not only have to delete the old Haiku partition on the SATA drive, but reformat the partition with an alien file system to completely rid it from its BFS-edness.

axeld in #3532:
The problem is that the BIOS does not tell Haiku that it booted from USB. Once in the kernel, Haiku usually has to guess the drive from which it had been booted before; it uses some kind of heuristics, but apparently, they could be improved as your case shows.

[luroh]

Captain's log, stardate 32974.

The symptom has changed to a "PANIC: could not mount boot device!" at the fourth bootsplash icon. Formatting the existing BFS volumes solves the problem. Pictures of 'syslog' will follow.

[x-ist]

A similar problem here. I installed Haiku on my USB flash stick. From time to time I burn a latest nightly to CD and try to boot from it. Although I configure the bootloader to use the CD at some point during loading it finds the USB stick installation and continues to load from there, disregarding the CD. However, when the USB stick is unplugged Haiku is loaded normally from CD.

[luroh]

Minor clarification and update: the issue is repeatable on my desktop computer by dd'ing a raw image to a USB stick and trying to boot from it. However, a USB stick with a raw image can be successfully booted from by disabling the SATA controller in BIOS.

An anyboot image dd'ed to a stick boots fine as is.

[waddlesplash]

Still an issue after the PM merge?