Protected Mode:

Hi all,

I am trying to run some code to switch the processor from real mode to
protected mode. I am using an ICE to debug and have been able to trace
the execution.

I have a valid gdt and idt setup, however when I try to execute my
C-code after switching the 32-bit protected code, it looks like the CPU
is still trying to execute the instructions as 16-bit instructions.
The 16-bit execution causes some side effects which I can track, a ram
location is changed. The ICE's trace is based on an option (i.e
dissassembles in real or protected mode), so it is no help. Only the
side effect clues me into what could be going on wrong.

The BIOS initial comes up and sets a gdt but only for 16-bit
instructions, so I have to recreate the gdt I would like to use.

The code I am using is very similar to many of the example found on the
web. I just modified existing code from:
http://my.execpc.com/~geezer/os/

Any suggestion on what I can try?

Chris

.

Relevant Pages

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