Re: [Qemu-devel] Re: Debugging with paging enabled

[Daniel Jacobowitz <drow@false.org>]

On Fri, Nov 10, 2006 at 03:56:01PM +0000, Paul Brook wrote:
> > Assuming that breakpoint locations are indeed meant to be virtual
> > addresses, GDB would have to evaluate the CS descriptor, add the CS
> > base to the EIP address and THEN check whether it knows the address.
> > But as it seems to be segment-agnostic it doesn't do that and things
> > break as a result.
> 
> As Dan said, gdb knows nothing about x86 segmentation. As soon as you have 
> nonzero segment bases you're pretty much on your own.
> 
> If you care about fixing this I suggest you get GDB folks to agree (and 
> document) how segmented memory models should work, then implement that model 
> in qemu. Hacking qemu to work for your particular case with unmodified gdb 
> probably "breaks" something else, so doesn't seem to improve the overall 
> usefulness.

I'd recommend the even simpler hack of having qemu report a PC that
included the segment base :-)

-- 
Daniel Jacobowitz
CodeSourcery