EXECUTIVE SUMMARY
The BIOS' order is more important than any other order because
the BIOS' order can't be changed unless you change the BIOS itself,
which might require a board swap in some cases. You just have to
accept that as a fact of life.
MORE DETAILS
There is an ordered set <1, 2, ...> of controllers seen by the
BIOS. When LILO tell the BIOS to read the kernel image, it has to
tell the BIOS which controller (host adaptor), which disk (LUN), and
which sectors to read.
How does LILO know which controller, disk, and sectors to tell
the BIOS to read? Well, someone has configured an "/etc/lilo.conf"
file that names a particular kernal image, as a unix file
specification: "/vmlinuz-2.0.23", for example. LILO scrutinizes the file,
and asks important questions, such as:
* Which filesystem is this file in?
* Which device and partition are the filesystem in?
* Which controller is the device on?
ending up with a number that identifies the controller in the kernel's
ordered set of controllers.
If the kernel uses a different ordering than the BIOS, then
LILO would have to map the kernel's ordering into the BIOS' ordering.
This would add yet another level of hareware-specific incantation into
an already complex invocation bordering upon dark magic.
Admittedly, you could do something like tell LILO, "please
boot /vmlinuz-2.0.23, oh, and by the way, tell the BIOS that it will
find this file on controller #2". But this would require manual
configuration, which whould be error-prone, and would totally stump
the inexperienced, leading to an irksome flood of messages asking for
help in making the Linux system boot.
Craig Milo Rogers
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