On 15/05/2013 14:50, Paolo Bonzini wrote:
Il 15/05/2013 11:31, KONRAD Frédéric ha scritto:
Hi,
We are trying to do a simple save/restore on the VM with icount enabled.
We saw that qemu_icount_bias and qemu_icount in cpus.c are not
saved/restored,
and icount_extra, icount_decr in CPUState neither, so the vm_clock is just
growing normally after restoring the VM is that normal?
We think that this is making the "replay" undeterminastic, which is bad for
reverse execution.
Is there a good reason for them not being saved?
No. You can probably move icount to timers_state. Something like
zeroing qemu_icount in cpu_disable_ticks() is required in order to save
qemu_icount_bias like the other members of timers_state. There is even
a dummy field that you can reuse to avoid the pain of adding a
subsection to vmstate_timers. :)
Paolo
Yes nice point :).
What about icount_extra and icount_decr defined in CPU_COMMON? in
cpu-defs.h?
int64_t icount_extra; /* Instructions until next timer event. */ \
/* Number of cycles left, with interrupt flag in high bit. \
This allows a single read-compare-cbranch-write sequence to test \
for both decrementer underflow and exceptions. */ \
union { \
uint32_t u32; \
icount_decr_u16 u16; \
} icount_decr; \
Thanks,
Fred
Thanks,
Fred
