Re: [Qemu-devel] [PATCH v2] rtl8139: implement 8139cp link status

[Amos Kong]

On 13/09/12 20:29, Stefan Hajnoczi wrote:
> On Thu, Sep 13, 2012 at 9:51 AM, Amos Kong <address@hidden> wrote:
> > From: Jason Wang <address@hidden>
> >
> > Add a link status chang callback and change the link status bit in BMSR
> > & MSR accordingly. Tested in Linux/Windows guests.
> >
> > The link status bit of MediaStatus is infered from BasicModeStatus,
> > they are reverse.
> >
> > Signed-off-by: Jason Wang <address@hidden>
> > Signed-off-by: Amos Kong <address@hidden>
> > ---
> > v2: don't add MediaState in RTL8139State to avoid migration trouble
> > ---
> >   hw/rtl8139.c |   19 +++++++++++++++++--
> >   1 files changed, 17 insertions(+), 2 deletions(-)
> >
> > diff --git a/hw/rtl8139.c b/hw/rtl8139.c
> > index 844f1b8..fa949ca 100644
> > --- a/hw/rtl8139.c
> > +++ b/hw/rtl8139.c
> > @@ -167,7 +167,7 @@ enum IntrStatusBits {
> >       PCIErr = 0x8000,
> >       PCSTimeout = 0x4000,
> >       RxFIFOOver = 0x40,
> > -    RxUnderrun = 0x20,
> > +    RxUnderrun = 0x20, /* Packet Underrun / Link Change */
> >       RxOverflow = 0x10,
> >       TxErr = 0x08,
> >       TxOK = 0x04,
> > @@ -3007,7 +3007,7 @@ static uint32_t rtl8139_io_readb(void *opaque, uint8_t 
> > addr)
> >               break;
> >
> >           case MediaStatus:
> > -            ret = 0xd0;
> > +            ret = 0xd0 | ~(s->BasicModeStatus & 0x0004);
> >               DPRINTF("MediaStatus read 0x%x\n", ret);
> >               break;
>
> This does not give any hint that BMSR & 0x4 is the link status
> (inverted).

only mentioned in the commitlog, will add a comment here.

> I suggest adding an enum like the other constants at the
> top of the file:
>
> ret = 0xd0 | (nc->link_down ? MSRLinkDown : 0);

Ok, I will update the patch.

> Regarding migration: do we migrate the NetClient->link_down field? If
> we only migrate the status register value then the link may actually
> be up at the net.c level.

I tried to add 'MediaStatus' to 'struct RTL8139State', and update
'VMStateDescription vmstate_rtl8139', then the value of MediaStatus
will be migrated.

But the idea in v2 is better.

> Stefan

Thanks.

--
                        Amos.