Subject: Re: Floppy - weird behaviour?
To: hypno <hypno@evilworks.com>
From: David Laight <david@l8s.co.uk>
List: port-i386
Date: 02/05/2003 22:05:27
> ! This is probably something David Laight could do as he is
> ! fixing the boot blocks up.
> 
> Yes, correct.
> 

It is a bit problematical though.  You don't want to stop the motor
if the drive is going to be used again anytime soon.  Otherwise
you have to wait (a bit) for spin up.

All the early disk accesses are also done via bios calls.  Just
writing to the floppy device registers could confuse the system
BIOS into thinking the motor was running when it isn't.
It isn't until the kernel initialises its own floppy driver
that any netbsd code that knows how to drive a floppy is loaded.

There is probably a bios call to stop the motor, but I don't
know whether it will restart automatically.  My system has too
many fans in it to let you hear the floppy going around.

Also the boot code will be passed device 0x0 when booting a CD
- the BIOS makes it look like a floppy (actually you read a
floppy image from one of the files on the CD).  If there are
bios calls to read the real CD I don't know what they are...
(and you would need the rockridge code for a unix system).

	David

-- 
David Laight: david@l8s.co.uk