readme

开源的BIOS启动软件

			Bios for EBSA-285
			-----------------

		Copyright (C) 1998-2000 Russell King.

Copyright: GPL

Various bits'n'pieces taken from the Linux kernel


This is a multi-function kernel loader for the EBSA-285 evaluation
board and other DEC21285-based systems.  It is capable of loading
a kernel over the following media:

1. locally attached network using BOOTP and TFTP protocols
2. from a local hard drive
3. via an Xmodem download


Supported devices
-----------------

Currently, bios has been tested with:

Class	Card					Status
Network	3com 3c592 Vortex NIC			[works]
	3com 3c905C Tornado NIC			[works]
	DEC Tulip				[unknown]
VGA	S3 Trio64V2+ VGA card			[works]
IDE	Promise UDMA33 IDE (raid) card		[works with ST35651A UDMA2 HD]
	Promise UDMA66 IDE card			[supported]
	CY82C693 IDE interface			[supported]
	(other IDE interfaces may work)

Compilation
-----------

To compile, edit the top-level make file and alter:

1) TEXTADDR to be an address in the EBSA-285's flash.
   The address is dependent on the bank number, and is calculated
   as follows:

	TEXTADDR = 0x410000c0 + bank * 0x00040000 (ELF)
	TEXTADDR = 0x410000a0 + bank * 0x00040000 (A.OUT)

2) CROSS_COMPILE to be the prefix to use for the ARM toolchain
   (either an A.OUT or ELF toolchain)

Next, type "make dep".  This will generate the required dependency
information.

Then, type "make".  This will produce two binary files:
 - bios.a.out or
 - bios.elf   - an unstripped file
 - bios       - the AIF image to program into the flash.

You can use the AIF image to program into the flash using the FMU
tool which comes with the EBSA285.


Configuration
-------------

The loader uses jumper J17 pins 11-12 to configure the root device
that the kernel will use.  With the jumper fitted, it will boot
from the /dev/hda3 device.  With it removed, the kernel will try to
get an NFS root filesystem.


Future
------

If you think the BIOS could do with some extra features, you are
welcome to generate some code for it, and send it to me at
<[e-mail]>.

Ideas thus far:
 * Fuller VT100 terminal emulation on VGA (but only as far as the
    features of the BIOS needs).
 * Textual configuration (eg, windowed)
 * Use on-board flash to store configuration information
 * Pre-compile time configuration of facilities
    (maybe borrow the Linux configuration system)?
 * SCSI support?

As always:
 * More ethernet cards supported
 * More VGA cards support
 * Other IDE chipsets