On 04/11/2011 03:24 AM, Ulrich Obergfell wrote:
typedef struct HPETState { @@ -248,7 +253,7 @@ static int hpet_post_load(void *opaque, int version_id) static const VMStateDescription vmstate_hpet_timer = { .name = "hpet_timer", - .version_id = 1, + .version_id = 3,Why jump from 1 to 3?.minimum_version_id = 1, .minimum_version_id_old = 1, .fields = (VMStateField []) { @@ -258,6 +263,11 @@ static const VMStateDescription vmstate_hpet_timer = { VMSTATE_UINT64(fsb, HPETTimer), VMSTATE_UINT64(period, HPETTimer), VMSTATE_UINT8(wrap_flag, HPETTimer), + VMSTATE_UINT64_V(saved_period, HPETTimer, 3), + VMSTATE_UINT64_V(ticks_not_accounted, HPETTimer, 3), + VMSTATE_UINT32_V(irqs_to_inject, HPETTimer, 3), + VMSTATE_UINT32_V(irq_rate, HPETTimer, 3), + VMSTATE_UINT32_V(divisor, HPETTimer, 3),Anthony, I incremented the version ID of 'vmstate_hpet' from 2 to 3 to make sure that migrations from a QEMU process that is capable of 'driftfix' to a QEMU process that is _not_ capable of 'driftfix' will fail. I assigned version ID 3 to 'vmstate_hpet_timer' and to the new fields in there too to indicate that adding those fields was the reason why the version ID of 'vmstate_hpet' was incremented to 3. As far as the flow of execution in vmstate_load_state() is concerned, I think it does not matter whether the version ID of 'vmstate_hpet_timer' and the new fields in there is 2 or 3 (as long as they are consistent). When the 'while(field->name)' loop in vmstate_load_state() gets to the following field in 'vmstate_hpet' ... VMSTATE_STRUCT_VARRAY_UINT8(timer, HPETState, num_timers, 0, vmstate_hpet_timer, HPETTimer), ... it calls itself recursively ... if (field->flags& VMS_STRUCT) { ret = vmstate_load_state(f, field->vmsd, addr, field->vmsd->version_id); 'field->vmsd->version_id' is the version ID of 'vmstate_hpet_timer' [1]. Hence 'vmstate_hpet_timer.version_id' is being checked against itself ... if (version_id> vmsd->version_id) { return -EINVAL; } ... and the version IDs of the new fields are also being checked against 'vmstate_hpet_timer.version_id' ... if ((field->field_exists&& field->field_exists(opaque, version_id)) || (!field->field_exists&& field->version_id<= version_id)) { If you want me to change the version ID of 'vmstate_hpet_timer' and the new fields in there from 3 to 2, I can do that.
It avoids surprises so I think it's a reasonable thing to do. But yes, your analysis is correct.
Regards, Anthony Liguori
Regards, Uli [1] Ref.: commit fa3aad24d94a6cf894db52d83f72a399324a17bb
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