Documentation

steven james pyro at linuxlabs.com
Mon May 5 09:53:01 CEST 2003


Greetings,

The confusion is that there are multiple stages to LinuxBIOS. All x86
machines start at 0xf000:fff0 in real mode. The flash itself lives at the
top of the 4GB address space and the chipset arranges for an alias at the
top of the 1MB real mode address space.

The instruction at that start address will be a jmp to the assembly
language initialization code. Once the memory is set up, the next stage is
copied from rom (possibly with decompression) to 0x80000 which includes
_start. That code consists of a little assembly language (equivilant to
crt0 in a normal C application) followed by the bulk of LinuxBIOS which is
compiled from C. That code is entered at hardwaremain.

G'day,
sjames
 


On Mon, 5 May 2003, Xavier Pegenaute wrote:

> Hello,
> 
> i'm doing documentation about the code of LinuxBios with ADLO for my 
> thesis, and i thought that may be you can helpme in things that are 
> usefull to know for understand the code of LinuxBios. Of course after 
> the document can be for linuxbios.
> 
> I started by a mail of Greg Watson that explain how is linked crt0.S and 
> linuxbios, after this i started to explain the main things of 
> hardwaremain.c that jump to the elfboot and finally elfboot to kernel.
> 
> Any one thing that is usefull to explain something else ?
> 
> Another thing that is a little confused in me .., the true point of 
> start code, in some info say that is in 0xf0000, but in the compilation 
> of ms7308e i see that is in:
> 
> linuxbios.map:00080004 T _start
> 
> i supose that then it depends of the motherboard ...
> 
> At the moment it's all.
> Thanks for all.
> Xavi.
> 
> _______________________________________________
> Linuxbios mailing list
> Linuxbios at clustermatic.org
> http://www.clustermatic.org/mailman/listinfo/linuxbios
> 

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