Jeff Dike wrote:
On Wed, May 04, 2005 at 10:28:28AM +0100, Ian Rogers wrote:
What I'm hoping to do is to use SKAS to create a second address
space I can, map, unmap, peek and poke from the first. The reason for
this is to allow an emulator to live in the first address space and the
emulated data... to live in the second.
UML obviously does this. Look at arch/um/kernel/skas/mem_user.c for the
basic primitives. The creation and destruction of address spaces is done
in arch/um/kernel/skas/mmu.c.
I've had a play with a simple test, but I need to work further on it.
mem_user.c seems clear enough but I am slightly baffled by what is
happening with the file descriptors in mmu.c.
I hope to be able to access the
second by altering the i386 selector value.
What's the i386 selector value?
I hope, for example, to set LDT 0 to point to the second address space.
I can then swap the value of 7 (index 0, LDT, ring 3) into fs or gs
whenever I hope to address the second address space. I can do similar
code with modify_ldt but I'm restricted to using mmap to allocate memory
and therefore I don't get a fully addressable 4gb address space.
Thanks for your help,
Ian Rogers
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