Actually it's not always zero because
- presave() calls e1000_mit_timer(), which sets mit_timer_on to 0 and
calls set_interrupt_cause(ICR);
- if there are pending events, set_interrupt_cause(ICR) detects a
raising edge, and doesn't filter out the interrupt since mit_timer_on
== 0. Therefore, the timer is reloaded and mit_timer_on is set to 1.
However, I've just realized that this is a mistake, since it would
need the post_load() to call qemu_mod_timer() when
mit_timer_on is migrated as "1", otherwise the interrupt delivery
would deadlock on the migrated system.
I think it's way better not to migrate mit_timer_on, so that the
migrated system sees mit_timer_on==0 and doesn't need to call
qemu_mod_timer() in post_load(). The first interrupt request
(set_interrupt_cause()) will cause an immediate interrupt.
Thanks,
Vincenzo
2013/7/29 Stefan Hajnoczi <stefa...@redhat.com>:
> On Fri, Jul 26, 2013 at 05:02:50PM +0200, Vincenzo Maffione wrote:
>> +static const VMStateDescription vmstate_e1000_mit_state = {
>> + .name = "e1000/mit_state",
>> + .version_id = 1,
>> + .minimum_version_id = 1,
>> + .minimum_version_id_old = 1,
>> + .fields = (VMStateField[]) {
>> + VMSTATE_UINT32(mac_reg[RDTR], E1000State),
>> + VMSTATE_UINT32(mac_reg[RADV], E1000State),
>> + VMSTATE_UINT32(mac_reg[TADV], E1000State),
>> + VMSTATE_UINT32(mac_reg[ITR], E1000State),
>> + VMSTATE_BOOL(mit_timer_on, E1000State),
>
> Why is this migrated? I it is always 0 since pre_save calls
> set_interrupt_cause(s, 0, s->mac_reg[ICR]).
--
Vincenzo Maffione
