Date: Fri, 26 Jun 1998 21:46:28 +0200 (CEST) From: Andrzej Bialecki <abial@nask.pl> To: Mike Smith <mike@smith.net.au> Cc: freebsd-small@FreeBSD.ORG Subject: Flashes and BIOS (was Re: I'm back.) Message-ID: <Pine.NEB.3.95.980626212536.25377B-100000@korin.warman.org.pl> In-Reply-To: <199806261729.KAA07996@antipodes.cdrom.com>
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On Fri, 26 Jun 1998, Mike Smith wrote:
> > * I just received a flash disk (16MB, M-Systems, ISA card), thanks to
> > Goran Hasse of Raditex, SE - I'll be experimenting with it till it starts
> > working... :-) (i.e. I want to boot from it, and somehow access it to
> > store the config data). I also plan to read the docs about Linux
> > implementation of Flash Filesystem (romfs). Any pointers appreciated!
>
> If this card has an on-board BIOS, I would be more than happy to help
> you implement a VM86-based BIOS-disk driver on -current. We have
> everything in place to make this pretty easy.
Yes, yes!!! That was what I also intended to pursue. You see, it has it's
own BIOS which makes it accessible from DOS as an IDE drive. There is a
driver for QNX, but (obviously) binary only. From the h/w point of
view the card is seen through a 10kB memory region (no IO adresses).
As I said I just received it today, plugged it into a spare machine and
verified that it works, nothing more (in fact, I even booted FreeBSD from
it, but of course couldn't mount root). Its BIOS hooks up normal int13, I
think... so yes, if we could call its BIOS under FreeBSD, this should
just work as expected (modulo some unexpectancies :-).
I have to display my total ignorance here: I'm not sure what happens to
the interrupt vectors once FreeBSD is booted - are they stored somewhere?
are they changed at all? I kind of vaguely remember them being located
somewhere near the 0:0 right after the POST completes (in real mode, just
after startup). What happens to them when freebsd switches to protected
mode? Is this memory area used at all? etc, etc...
As for the driver: I'm totally ignorant in writing device drivers (and
anything that must reside in kernel) - all I did thus far was to run the
scripts in /usr/share/examples, and look at the code they produced... but
I'm determined to learn, and code what I can. :-)
> > One thing that should be discussed before this is the use of
> DEVFS/SLICE
> DEVFS should not be used in 2.2, and SLICE isn't there at all. For a
> 3.0-based PicoBSD, it's ideal.
Well, we might bifurcate the types further... into
{dial,net,isp}/{devfs,nodevfs}
but this starts to be messy... Perhaps I'll come up with a feature-level
configurator instead of defining separate types with their own
hierarchies... but this complicates calculations of MFS sizes...
Andrzej Bialecki
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abial@nask.pl | if(halt_per_mth > 0) { fetch("http://www.freebsd.org") }
Research & Academic | "Be open-minded, but don't let your brains to fall out."
Network in Poland | All of the above (and more) is just my personal opinion.
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