[RFC PATCH v2] x86: mmiotrace - trace memory mapped IO

[Pekka Paalanen]

> > could you please send us a patch for the whole mmiotrace kernel-side 
> > feature, so that we can have a look at the general structure of this? 
> > (and the interaction with change_page_attr(), etc.) Even if it's not 
> > functional (and wont even build/boot) at the moment. Thanks,

And here's mmiotrace. This works for me (amd64), but not for a test user
who has 32-bit x86. We have not had the chance to debug it yet.
The symptom is "everything locked up" after insmodding testmmiotrace.ko,
targeting the mid-point of his VRAM. And there's the "undefined symbol
init_mm" problem on 32-bit, but we just put the export back in (not
included in these patches).

No-one has tried this on SMP. I have a Core 2 Duo laptop where I will
test this when I get the chance.