Re: [Qemu-devel] paravirtual mouse/tablet

[Anthony Liguori]

On 01/13/2011 10:18 AM, Avi Kivity wrote:
> On 01/13/2011 12:19 PM, Gerd Hoffmann wrote:
> >   Hi,
> >
> > Just throwing a quick writeup into the ring to kickstart the design 
> > discussion ;)
> >
> >
> > typedef struct qemu_pvtablet_message {
> >      uint32_t size;            /* whole message size */
> >      uint32_t type;            /* qemu_pvtablet_type */
> >      uint64_t tv_secs;
> >      uint64_t tv_usecs;
>
> time relative to what base?
>
> can we actually provide it? if the tablet is remote, there may not be 
> a synchronized time source.

I had the same thought, but if it's just treated as time since the init 
message, the guest is capable of working it out (minus drift).

> >      union {
> >          qemu_pvtablet_position position;
> >          qemu_pvtablet_button   button;
> >          qemu_pvtablet_display  display;
> >      } m;
> > } qemu_pvtablet_message;
>
> So the message size for a qemu_pvtablet_position would only include 
> the position member?

I didn't comment on this because I was treating this as a protocol 
proposal and not actual code but usually the following is clearer:

struct qemu_pvtablet_hdr {
    uint32_t size;
    uint32_t type;
    uint64_t tv_secs;
    uint64_t tv_usecs;
};

struct qemu_pvtablet_position {
    struct qemu_pvtablet_hdr hdr;
    uint32_t x;
    uint32_t y;
};

union qemu_pvtablet_message {
    struct qemu_pvtablet_hdr hdr;
    struct qemu_pvtablet_position position;
    ...
};

Regards,

Anthony Liguori