Re: [Qemu-devel] [PATCH RFC] ps2: set the keybord output buffer size as the same as kernel

[Juan Quintela]

"Gonglei (Arei)" <address@hidden> wrote:
>>   Hi,
>> 
>> > Anything bigger than 16bytes, no?  And that is the whole point that we
>> > are talking about?  Or the 16bytes that we are using can be at any place
>> > on the buffer?
>> 
>> Yes.  It's a ring buffer, with rptr pointing to the first used element
>> and wptr pointing to the first free element.
>> 
>> So, what we need is a function to move the content we are interested
>> (between rptr and wptr) in to the head of the ring buffer, set rptr to
>> 0, set wptr to count.  We obviously need to do that in post_load(), but
>> as I've noticed meanwhile also in pre_save, otherwise old qemu will get
>> things wrong in case the buffer is wrapped (rptr > wptr).
>> 
> Hi, Gerd. Maybe we just need to do in post_load(). Such as the follow code:
>
> static int ps2_kbd_post_load(void* opaque, int version_id)
> {
>     PS2KbdState *s = (PS2KbdState*)opaque;

cast not needed.

>     PS2State *ps2 = &s->common;
>     PS2Queue *q = &ps2->queue;
>     int size;
>     int i;
>         
>     if (version_id == 2)
>         s->scancode_set=2;
>     /* the new version id for this patch */
>     if (version_id == 4) {
>         return 0;
>     }
>     /* set the useful data buffer queue size, < PS2_QUEUE_SIZE */
>     size = MIN(q->count, PS2_QUEUE_SIZE);
>     printf(" ==kbd: rptr: %d, wptr: %d, count: %d, size: %d\n", q->rptr, 
> q->wptr, q->count, size);
>     for (i = 0; i < size; i++) {
>         /* move the queue elements to the start of data array */
>         q->data[i] = q->data[q->rptr];

It is me, or this don't work if the destination and source regions
overlap?  Yes, it depens on how it overlaps.

>         if (++q->rptr == 256) {
>             q->rptr = 0;
>         }
>     }
>     /* reset rptr/wptr/count */
>     q->rptr = 0;
>     q->wptr = size;
>     q->count = size;
>     ps2->update_irq(ps2->update_arg, q->count != 0);
>
>     return 0;
> }
> Any problem? Thanks.
>
> Best regards,
> -Gonglei