SGABIOS checksum [[e-mail]: Re: SeaBIOS, serial output, and grub]

[Peter Stuge]

Hi Nathan,

there was some discussion on the coreboot mailing list, and it seems
that the SGABIOS binary doesn't have a checksum calculated for it,
which means that some BIOSes refuse to initialize it.

The SeaBIOS project maintained by Kevin has a utility for calculating
checksums, available at:

http://git.linuxtogo.org/?p=kevin/seabios.git;a=blob;f=tools/checksum.py;h=8...

Kevin, I can't find that buildrom.py script in seabios.git?

//Peter

----- Forwarded message from Kevin O'Connor  -----

From: Kevin O'Connor 
To: [e-mail]
Subject: Re: [coreboot] SeaBIOS, serial output, and grub
Date: Thu, 14 May 2009 09:19:33 -0400

On Wed, May 13, 2009 at 11:23:52PM -0400, Ward Vandewege wrote:
> > which is correct (the last two digits are 00).
>
> Huh:
>
> $ v ../payloads/sgabios.bin 
> -rwxr-xr-x 1 root src 3169 2009-04-29 13:56 ../payloads/sgabios.bin*
> $ tools/checksum.py <../payloads/sgabios.bin 
> sum=50b76

Heh - sgabios isn't properly checksumming.  It was just dumb luck that
my binary summed to zero.

This is a hack, but you can use seabios' rom building tool to make it
work:

tools/buildrom.py ../payloads/sgabios.bin sgabios-cksum.bin

Someone should follow up with google on this..

-Kevin

[Nathan Laredo]

I already have a fix for this not yet committed -- including
calculation of the rom size byte in the linker script as well as doing
the 2KB alignment of the end of the rom.

I will try to get the new code checked in within the month.   Please
poke me again if you haven't seen updates before the end of May (I
have a new baby at home now).

- nathan laredo
[e-mail]

On Thu, May 14, 2009 at 06:38, Peter Stuge  wrote:
> Hi Nathan,
>
> there was some discussion on the coreboot mailing list, and it seems
> that the SGABIOS binary doesn't have a checksum calculated for it,
> which means that some BIOSes refuse to initialize it.
>
> The SeaBIOS project maintained by Kevin has a utility for calculating
> checksums, available at:
>
> http://git.linuxtogo.org/?p=kevin/seabios.git;a=blob;f=tools/checksum.py;h=8...
>
> Kevin, I can't find that buildrom.py script in seabios.git?
>
> //Peter
>
> ----- Forwarded message from Kevin O'Connor  -----
>
> From: Kevin O'Connor 
> To: [e-mail]
> Subject: Re: [coreboot] SeaBIOS, serial output, and grub
> Date: Thu, 14 May 2009 09:19:33 -0400
>
> On Wed, May 13, 2009 at 11:23:52PM -0400, Ward Vandewege wrote:
> > > which is correct (the last two digits are 00).
> >
> > Huh:
> >
> > $ v ../payloads/sgabios.bin
> > -rwxr-xr-x 1 root src 3169 2009-04-29 13:56 ../payloads/sgabios.bin*
> > $ tools/checksum.py <../payloads/sgabios.bin
> > sum=50b76
>
> Heh - sgabios isn't properly checksumming.  It was just dumb luck that
> my binary summed to zero.
>
> This is a hack, but you can use seabios' rom building tool to make it
> work:
>
> tools/buildrom.py ../payloads/sgabios.bin sgabios-cksum.bin
>
> Someone should follow up with google on this..
>
> -Kevin
>
> ----- End forwarded message -----

SGABIOS checksum [[e-mail]: Re: SeaBIOS, serial output, and grub]

[Jason Wang]

Hi Peter,
   There is an tools[1] which can calculate the checksum. I am not sure if
it can help,
really hope it can help
[1]http://vps.dorilex.net/pub/scm/usbrom.git

On Thu, May 14, 2009 at 9:38 PM, Peter Stuge  wrote:
> Hi Nathan,
>
> there was some discussion on the coreboot mailing list, and it seems
> that the SGABIOS binary doesn't have a checksum calculated for it,
> which means that some BIOSes refuse to initialize it.
>
> The SeaBIOS project maintained by Kevin has a utility for calculating
> checksums, available at:
>
> http://git.linuxtogo.org/?p=kevin/seabios.git;a=blob;f=tools/checksum.py;h=8...
>
> Kevin, I can't find that buildrom.py script in seabios.git?
>
> //Peter
>
> ----- Forwarded message from Kevin O'Connor  -----
>
> From: Kevin O'Connor 
> To: [e-mail]
> Subject: Re: [coreboot] SeaBIOS, serial output, and grub
> Date: Thu, 14 May 2009 09:19:33 -0400
>
> On Wed, May 13, 2009 at 11:23:52PM -0400, Ward Vandewege wrote:
> > > which is correct (the last two digits are 00).
> >
> > Huh:
> >
> > $ v ../payloads/sgabios.bin
> > -rwxr-xr-x 1 root src 3169 2009-04-29 13:56 ../payloads/sgabios.bin*
> > $ tools/checksum.py <../payloads/sgabios.bin
> > sum=50b76
>
> Heh - sgabios isn't properly checksumming.  It was just dumb luck that
> my binary summed to zero.
>
> This is a hack, but you can use seabios' rom building tool to make it
> work:
>
> tools/buildrom.py ../payloads/sgabios.bin sgabios-cksum.bin
>
> Someone should follow up with google on this..
>
> -Kevin
>
> ----- End forwarded message -----

[Kevin O'Connor]

On Thu, May 14, 2009 at 03:38:33PM +0200, Peter Stuge wrote:
> Hi Nathan,
>
> there was some discussion on the coreboot mailing list, and it seems
> that the SGABIOS binary doesn't have a checksum calculated for it,
> which means that some BIOSes refuse to initialize it.
>
> The SeaBIOS project maintained by Kevin has a utility for calculating
> checksums, available at:
>
> http://git.linuxtogo.org/?p=kevin/seabios.git;a=blob;f=tools/checksum.py;h=8...
>
> Kevin, I can't find that buildrom.py script in seabios.git?

Sorry - it's there now.

It's in "tools/buildrom.py" in the repo at:

git clone git://git.linuxtogo.org/home/kevin/seabios.git

It's also at:

http://git.linuxtogo.org/?p=kevin/seabios.git;a=blob;f=tools/buildrom.py;h=1...

The script pads a rom to 512 bytes, sets the rom length, and uses byte
7 as a checksum.  It wasn't designed for sgabios, but looks like it
will work.

-Kevin