Re: i386: far jumps

[Emanuele Altieri <ealtieri@hampshire.edu>]

On Fri, 2002-07-19 at 13:44, h-peter recktenwald wrote:
> On 15 Jul 2002 22:21:26 -0400
> Emanuele Altieri <ealtieri@hampshire.edu> wrote:
> 
> > Greetings,
> > 
> > I'm doing some experiments with far jumps to different code segments.
> > For example:
> > 
> >    ljmp *%fs:hello
> > 
> > I get a general protection error. I don't understand why. I believe it's
> > a notation error. Can anybody see it?
> > 
> > I'm interested in this because I need the segment argument of ljmp to be
> 
> 	Linux?

No (/ not yet). I'm just experimenting on Intel's segmentation and task
support with a small OS that I created for this purpose. I'm using GCC
and GAS to implement it.

By the way, I found a workaround to the ljmp problem:

    pushw <segment>
    pushl <offset>
    lret

For example

    pushw $16
    pushl $hello
    lret

This is equivalent to "ljmp $16, $hello", but now the segment and offset
arguments do not need to be constants.


  -Emanuele