[Qemu-devel] Re: [PATCH 0/4] Fix VMState design flaws

[Paolo Bonzini]

On 09/14/2009 10:50 PM, Juan Quintela wrote:
> Paolo Bonzini<address@hidden>  wrote:
> > >     * Add version_id field to post_load().  Now we can assign default values
> > >       in post_load for old versions of the state (ps2_kbd as example).
> >
> > While this is a good idea, why don't we first reset the devices upon
> > load, which would also set the default values?...
>
> It is safe to do that unconditionally?
> If so, I am all for it.  We can:
> - add reset field to vmstate
> - add default values to some fields, if it makse sense (haven't yet
>    looked at reset code).

The PS2 reset is this:

static void ps2_common_reset(PS2State *s)
{
    PS2Queue *q;
    s->write_cmd = -1;
    q = &s->queue;
    q->rptr = 0;
    q->wptr = 0;
    q->count = 0;
    s->update_irq(s->update_arg, 0); // calls kbd_update_kbd_irq
}

static void ps2_kbd_reset(void *opaque)
{
    PS2KbdState *s = (PS2KbdState *) opaque;

    ps2_common_reset(&s->common);
    s->scan_enabled = 0;
    s->translate = 0;
    s->scancode_set = 0;
}

All of these are later reset by load.  The update_irq may seem unsafe, 
but maybe deasserting an IRQ is better than leaving it in whatever state 
it was left by the previous VM...

Paolo