[Qemu-devel] Re: Debugging with paging enabled

[Marcel Kilgus <qemu@mail.kilgus.net>]

Paul Brook wrote:
> As Dan said, gdb knows nothing about x86 segmentation. As soon as you have
> nonzero segment bases you're pretty much on your own.

I was just wondering, because I didn't invent that "move the code to
3GB base" but it is (was?) the model used by Linux, at least in very
early versions (I'm not accustomed with the current code base). So I
didn't expect to be the first person stumbling over this shortcoming.

> 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.

Nah, I've already spent way more time on this than I can really
afford, though it was quite fun for a change. And my hack works
perfectly for my needs, so I'm fine. At least my findings are now
documented in the list archives and anybody with a similar problem can
now read it up.

All the best, Marcel