User manual

Etherboot User Manual

Finally some recent motherboard have ﬂash BIOSes which contain space where an extension BIOS

such as Etherboot can be inserted. The Phoenix Award BIOSes can be modiﬁed using a program

called cbrom.exe possibly here (http://www.ping.be/bios). Or do a Web search for it. No success has

been reported for AMI BIOSes. Dirk von Suchodoletz maintains a list of successes and failures here

(http://goe.net/anleitungen/award_board.html).

Here is some text contributed by Dirk von Suchodoletz. He hopes to put it on a web site someday:

6.4 Using your mainboard’s BIOS to integrate etherboot-code

Newer mainboards that have an AWARD-BIOS can use etherboot without

separate EPROMS and therefore without the necessity of having a

EPROM-programmer[?]. (Heinrich Rebehn wishes to add: Flashing the BIOS

is always a (small) risk. Flashing with unsupported, hacked BIOS image

is *dangerous* and may render your PC unbootable. If you don’t

have access to a PROM burner you should stay away from experimenting.) In

order to do this, you need 2 software tools: awdflash.exe, which should be

included in your mainboard package, and cbrom.exe, which is an OEM-tool

that allows modifications of the BIOS. awdflash.exe reads and writes

the flashrom content, whereas cbrom.exe is used to analyse the content

of the AWARD BIOS image. cbrom.exe can also add code to the BIOS image

or remove components. This way you can easily integrate etherboot into

your mainboards without even opening the PC’s case.

After the BIOS image has been saved (e.g. as bios.bin), or in case the

current version of the BIOS has been copied from the board manufacturer’s

website, ’cbrom bios.bin /d’ shows how much space is left on the image

for your code.

As the flashrom holds the compressed BIOS, cbrom will also compress

the code when adding it to the BIOS. Therefore, 8 to 20 kbyte of free

memory is needed, depending on the network adapter’s driver. In case not

enough memory is left, unneeded BIOS components can be removed from the

BIOS image to regain space: the manufacturer’s logo or the Symbios/NCR

SCSI-code are note needed for diskless systems. ’cbrom bios.bin

/[pci|ncr|logo|isa] release’ will remove those unnecessary components.

The command line "cbrom bios.bin /[pci|isa] bootimg.rom [D000:0]" adds

the compiled etherboot code to the bios. bootimg.rom is the code we

would use to burn onto EEPROMs in other cases. Depending on your network

card, either the pci or isa options have to be used. With isa cards

you have to tell cbrom to which RAM location the code will be extracted

at boot time. Attention: Compile the etherboot with the -DASK_BOOT or

-DEMERGENCYDISKBOOT option to be able to access a disk. The code added

by cbrom will be executed before the computer seeks for a boot disk

or floppy.

6.5 Booting with a DOS executable (COM) file

If the computer has to be used with more than one operating systems,

for example using the computer as an X-Terminal in addition to the

already installed NT on the harddrive, etherboot has to be used with

the compile-time option -DASK_BOOT. In case hardware-conflicts between

Windows NT and the installed EPROM exist, creating DOS Executables