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

[Markus Armbruster]

"Gonglei (Arei)" <address@hidden> writes:

>> 
>> "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.
> This is the original code, I don't change it. Maybe I should post the
> diff file, Sorry.
>
>> 
>> >     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.
> Good catch, Juan, Thanks. It should use a temp data array to save the 
> q->data[] value,

Check out memmove().