Using int 13 while BSD is running

[Jason Dictos]

> To Jason: take care not to *write* anything to the disk via int 13h.
> I still don't think I understand why you are using FreeBSD for this
specific purpose. Why if you just >spend time escaping from the OS?

We actually _like_ protected mode, it allows us to be more flexible and our
code doesn't have to be bastardized with 16 dos compilers ;). However in dos
we have garanteed hard drive support via int13 (Well almost garanteed, but
if an os can boot of the computer, we can access the disk), and I'm looking
for the same sorta garantee in BSD. People will be using this with raid
controllers, scsi hard disks, and ide drives (Server recovery), so there
will be many times when the hardware running the hd requires specific
support, which BSD may or may not have, point is we dont' want to manage
that.

Make sense?

-Jason

-----Original Message-----
From: Sergey 'DoubleF' Zaharchenko [mailto:doublef at tele-kom.ru] 
Sent: Wednesday, March 10, 2004 5:51 AM
To: Jason Dictos
Cc: Dan Nelson; ''freebsd-questions at freebsd.org' '
Subject: Re: Using int 13 while BSD is running

On Tue, 9 Mar 2004 22:12:31 -0800
Jason Dictos <jason.dictos at yosemitetech.com> probably wrote:

> Aren't the nodes "/dev/ad[0-9] (ide) or /dev/da[0-9] (scsi/usb)" 
> created by their device drivers, i.e. protected mode device drives? 
> That would mean that I would have to make sure that the hardware is 
> supported by a device driver, whereas if I had raw int 13 access I 
> would be garanteed access to the drive the system booted from, and any 
> other bios addressable device, without having to load any driver for the
hardware.
> 
> -Jason

Argh, I didn't get your point first. I thought your hardware wasn't
supported by int 13h, and you were trying to get FreeBSD drivers to work for
you in real mode...

Any real HDD's out there not supported by FreeBSD but supported by BIOS'en?

Somewere around then Dan Nelson <dnelson at allantgroup.com> probably
replied:

> I guess it's possible, since you have to use the bios to make VESA 
> video calls, and they work.  /sys/i386/isa/vesa.c has most of the 
> stuff you would need.  Also see the i386_vm86() userland function; you 
> may not even need to mess around inside the kernel.

That's v86 mode, not real mode. Sometimes it makes a difference. It depends
on how that particular BIOS was written.

To Jason: take care not to *write* anything to the disk via int 13h.
I still don't think I understand why you are using FreeBSD for this specific
purpose. Why if you just spend time escaping from the OS?

--
DoubleF
All I ask is a chance to prove that money can't make me happy.

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