Subject: Boot ROM hacking
To: None <port-i386@netbsd.org>
From: Andrew Gillham <gillhaa@ghost.whirlpool.com>
List: port-i386
Date: 12/16/1999 17:32:40
Hello,

Has anyone here done much with 'netboot' ROMs?  I am attempting to
drop one into my BIOS, but it is not doing anything.  I suppose I
should first test it on an EPROM on an expansion card first, but
since the NCR BIOS works great stuffed in the BIOS, I thought I
would try that first.  I am using the 'CBROM.EXE' utility from
Award to "release" the NCR BIOS (I have a Soyo Sy6BA+) and free
up space for netboot.rom.  I created a 64K ROM with ROM_DEBUG
defined, and managed to stuff it into the BIOS image with the
following:
	cbrom bios.bin /other 4086:0000 netboot.rom
(I'm not sure what the address means, but according what is inside
the BIOS now, it doesn't appear to be the actual address to locate
the ROM at)

This creates a working bios.bin that I can flash to my motherboard,
but I don't see any of the ROM_DEBUG output, so I'm assuming the
ROM is not working.  I enabled the PCI Expansion ROM stuff also,
and it didn't make a difference.

Anyway, I know what I want to do is a total hack, but my hope is
to create a boot ROM that can support netbooting, (and possibly)
bios booting, without requiring a special EPROM on a NIC.  My 
theory would be to build a small check into the code, so that if
a video ROM (or something similar) is found at xxxx:xxxx the boot
code would either wait for a keypress (with a timeout), or just
return.  This way you could have a serial console system, and
pop a video card in and have somewhat "normal" operation.

-Andrew
-- 
-----------------------------------------------------------------
Andrew Gillham                            | This space left blank
gillham@whirlpool.com                     | inadvertently.
I speak for myself, not for my employer.  | Contact the publisher.