[Qemu-devel] QVM86, SKAS.. many modules, one vision?

[Ian Rogers]

Hi,

I recently spent some effort working out what Separate Kernel Address 
Space (SKAS) did for user-mode-linux (UML). The results of this keen be 
seen here:

http://news.gmane.org/group/gmane.linux.uml.devel/last=/force_load=t
on the thread "Using SKAS, any examples?"

the conclusion to this is that with SKAS you can create separate address 
spaces and map pages (possibly shared) into them. You can then use 
ptrace to control the execution of something in that separate address space.

This is all well and good, but when emulating one instruction set on 
another the executing code needs to peek and poke the separate address 
space. With SKAS this can only be done by using a page with a shared 
mapping, or by executing some host machine code in the separate address 
space.

What would be good is if multi-segments could be enabled and then 
cs/ds/es could be used by the emulator and fs/gs could map to higher in 
the linear address space and onto the separate address spaces. These 
address spaces would then be addressable with just a segment over-ride.

It seems these goals are likely in part to be shared by qvm86 and kqemu. 
Is it worth working toward a unified Linux module specifically for 
emulation?

Regards,

Ian Rogers
- http://www.cs.manchester.ac.uk/apt/projects/jamaica
- http://www.binarytranslator.org/