Re: BIOS and basic hardware drivers

Tauno Voipio (tauno.voipio@xxxxxxxxxxxxx) writes:
Haines Brown wrote:
I have a situation in which a debian cd installation disk won't boot,
but a Knoppix livecd disk will boot, and so I need to understand better
how the initial drivers get loaded. If I try to boot the debian cd
installation disk without offering any alternative boot method in BIOS,
I get a boot failure, system halted error.

It is my understanding that the CPU calls a set of programs on the ROM
chip, one of which is BIOS. I gather that BIOS holds a series of device
drivers that enables the system to function prior to boot. BIOS
setup seems to control which drivers get loaded so that a boot can
begin. Is this accurate?

In the case of my problem, there are certain drivers that will be needed
for the system to access my IDE cdrom drive. How can I find out what
they are and verify that the BIOS has indeed loaded them?

If the system accesses the cdrom in some cases (Knoppix), but not others
(debian install disk), should I infer that the debian install disk needs a
driver that the Knoppix disk does not? What could distinguish the two
disks in terms of their initial requirements?

If a needed driver, such as the one to access a cdrom drive, is not
being loaded, can I get it to behave?

What is the correct term to refer to the drivers built into BIOS, as
distinguished from the drivers in initrd?


The CD boot is a kludge: In principle, there is
a copy of a boot diskette image on the CD, and
it is shown to the boot code as the first diskette
(BIOS call 0x13, device 0x00).

The diskette image stays there until the booted
code either sends an acknowledgement message to
the BIOS or simply by-passes the BIOS drivers
with own drivers (like those in the Linux kernel).

For details, Google for 'El Torito specification'.

I guess that the boot actually succeeds, but the
installation CD boot image does not understand
your drive, but Knoppix does.

Of course, he didn't define "won't boot".

There can be issues related to the bios and the specific distribution
(or rather how that distribution lays the boot on the CD or DVD).

The BIOS sees the CD as a large floppy, as you point out. But older
BIOS's expect things one way, while more recent BIOS's expect things
to be a different way. A given distribution has to decide which to
be compatible with, and as the older hardware recedes in the distance,
it's more likely to be compatible with newer hardware than old. And if
that's the issue, the CD won't boot on a computer with an older BIOS.

I certainly have the problem, and to boot a more recent version of
the distribution I use, I have to put smartbootmanager on a floppy, and
tell the BIOS to boot from the floppy, and then the smartbootmanager
will actually do the booting from the CD/DVD.

Of course, the original poster is so vague that it's hard to tell
what his problem might be. He's assuming he knows where the problem
lies, but that isn't necessarily the case.

It could also be a simple thing like one specific CD has been written
wrong so it won't actually boot. People do that all the time, they end
up writing the image to the CD as a file rather as an image to be
layed all over the CD. Other times they simply do a bad write, and
the CD isn't useable.

Michael

.

Relevant Pages

  • Re: maximum hard drive size in Latitude cpi
    ... > actually written a boot loader they won't be so adamant about how "Windows ... > of the disk, and while it is being read off of the disk the machine is ... > limitatoins of that BIOS. ... After that the kernel takes over. ...
    (comp.sys.laptops)
  • Re: Grub hangs - two hard drives and a CD
    ... > What you wrote is all based on a wrong assumption that grub numbers drives ... > that the BIOS will call to boot an OS. ... The Bios calls to read disk require the register DL to ...
    (comp.os.linux.setup)
  • Re: Installation: doesnt see setup files on hard drive?
    ... > disk the BIOS is set to boot from must have an appropriate Master Boot ... I was worried about those points you made above so I removed all drives except the one I want to instll ...
    (microsoft.public.win2000.general)
  • Re: During reinstallation Im told that setup cant find the hard drive/mass storage device - whY?
    ... I'll move the "Gb NIC1" item up in the boot sequence. ... handled/populated by the BIOS. ... I've got both drivers on diskette now. ...
    (microsoft.public.windows.server.sbs)
  • Re: Is it possible to read BIOS setting?
    ... Say the kernel starts complaining about a disk failure, ... activate the program that will change the BIOS to boot from a flash device ... The flash or cdrom will boot up and copy the image from its ... Is it possible to read BIOS setting? ...
    (freebsd-questions)