Re: [coreboot] Where is the first instrucion?

[Rudolf Marek]

Hi,

I guess your question is more general than the coreboot related right?

If you have a firmware image dump of the flash (not the file you download from
board vendor) then yes, first location to be executed is the instruction located
16 bytes before end of the image.

In coreboot see in build/ bootblock_inc.S which also has reset16.inc and
entry16.inc which is a real start. Consult the Intel or AMD manual to see the
CPU state after reset. The CPU starts in real mode, but CS base is shifted to
last 64KB before end of 4GB address space. In general your CPU starts in
compatible mode with 8086 manufactured in 1978.

Thanks
Rudolf

Where is the first instrucion?

[Rafael Machado]

Hi Peter and Rudolf.
Thanks for the answers and tips. They are realy helpfull !
I'll take a look.

Rafael R. Machado

Em Sáb, 9 de jan de 2016 17:19, Rudolf Marek 
escreveu:
> Hi,
>
> I guess your question is more general than the coreboot related right?
>
> If you have a firmware image dump of the flash (not the file you download
> from
> board vendor) then yes, first location to be executed is the instruction
> located
> 16 bytes before end of the image.
>
> In coreboot see in build/ bootblock_inc.S which also has reset16.inc and
> entry16.inc which is a real start. Consult the Intel or AMD manual to see
> the
> CPU state after reset. The CPU starts in real mode, but CS base is shifted
> to
> last 64KB before end of 4GB address space. In general your CPU starts in
> compatible mode with 8086 manufactured in 1978.
>
> Thanks
> Rudolf