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x86 programming question




Erwin Rol wrote:

> On 23 Aug 2001 13:19:54 -0500, Joel Sherrill wrote:
> 
>> Hi,
>> 
>> On the pc386 BSP, can I make a BIOS int call from protected mode
>> (easily).  If not, I want to make a bios call in the start16.S code,
>> store the result and use it later.  This is simply a call to return
>> the size of memory.  Advice appreciated. :)
>> 
> 
> AFAIK it is done via a int 0x?? and passes the parameters in registers
> and the resulets too. A look at the lilo code or the linux kernel start
> code might give you some hints.

Rosimildo replied privately and made it clear I did not ask a clear 
question. :)

I know the interrupt and know how to write the code in real mode to do 
this call.  However,
the results of this call are of more use in protected mode.  So I saw 
only a handful of options:

  + figure out how to do the BIOS call in protected mode
  + do the BIOS call in real mode and figure out how to save the results
      in memory in such a way that they can be retrieved in protected mode.
  + (from Rosimildo) leave the memory size in a register at the time of
     transition from real to protected mode then save it away for later use.

So ideally I would like a generic way to perform a BIOS call from protected
mode. 

Thanks.

> 
> - Erwin
> 
> 
> 
>> -- 
>> Joel Sherrill, Ph.D.             Director of Research & Development
>> joel at OARcorp.com                 On-Line Applications Research
>> Ask me about RTEMS: a free RTOS  Huntsville AL 35805
>> Support Available                (256) 722-9985
> 

-- 
-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel at OARcorp.com                 On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
Support Available                (256) 722-9985