Re: [Qemu-devel] Saving and restoring CPU state

["andrzej zaborowski" <balrog@zabor.org>]

On 18/04/07, Rob Landley <rob@landley.net> wrote:
> On Thursday 12 April 2007 12:16 pm, eady wrote:
> > I'm still looking for any suggestions on how to save and restore the
> > target cpu state from within a custom instruction in op.c. I basically
> > want a custom instruction to save the cpu state to a data structure and
> > then continue on normally, a second custom instruction would then be
> > used to restore the cpu state from the saved data structure at a later
> > time thereby rolling back the execution of the cpu. I've tried saving
> > and restoring env->eip within my custom instructions but this has no effect.
>
> How do you roll back all the writes to memory and interactions with devices
> the processor may have done?
>
> Saving and restoring _just_ the processor state is what setjmp/longjmp does,
> and there's all sorts of restrictions on its' use...

Saving and restoring just (part of) the processor state kindof is done
by i386 instructions like syscall/sysret, sysenter/sysexit, SMM/RSM
stuff and other instructions. Have a look at target-i386/helper.c

HTH,
Andrzej