On 04/25/15 02:10, Michael van Elst wrote:
There is no safe way to identify the boot disk from information passed
by the BIOS. Here is what the MD code for x86 does: 1. BTINFO_ROOTDEVICE
....
3. BTINFO_BOOTDISK
a) ...
b) ...
c) bootloader passed BIOS disk number for a CD
Search for the first "cd" device, you can only boot from unit 0.
Pass driver instance (and partition 0) to MI code.
Well on our Dell system this assumption is invalid. When booting from a
virtual CD image this is emulated as a USB cdrom. SATA cdroms attached
to the system will be found/attached first. USB cdroms later in the boot
sequence. The 'first device' heuristic leads to surprising behavior in
the case. In order not to silently switch the boot device you need to
completely disable the SATA controller in the BIOS. So maybe this logic
should be revisited.
Frank
