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Date: Fri, 14 Sep 2012 17:20:24 +0800
From: Amos Kong <akong@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v3] rtl8139: implement 8139cp link status
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: jasowang@redhat.com, mst@redhat.com, aliguori@us.ibm.com, stefanha@linux.vnet.ibm.com, qemu-devel@nongnu.org

On 14/09/12 16:36, Paolo Bonzini wrote:
> Il 14/09/2012 04:16, Amos Kong ha scritto:
>> +            /* The LinkDown bit of MediaStatus is inverse with link status */
>> +            ret = 0xd0 | (s->nic->nc.link_down ? MSR_LinkDown : 0);
>>               DPRINTF("MediaStatus read 0x%x\n", ret);
>>               break;
>>
>> @@ -3453,12 +3466,27 @@ static void pci_rtl8139_uninit(PCIDevice *dev)
>>       qemu_del_net_client(&s->nic->nc);
>>   }
>>
>> +static void rtl8139_set_link_status(NetClientState *nc)
>> +{
>> +    RTL8139State *s = DO_UPCAST(NICState, nc, nc)->opaque;
>> +
>> +    if (nc->link_down) {
>> +        s->BasicModeStatus &= ~0x0004;
>> +    } else {
>> +        s->BasicModeStatus |= 0x0004;
>> +    }
>> +
>> +    s->IntrStatus |= RxUnderrun;
>> +    rtl8139_update_irq(s);
>> +}
>> +
>
> Actually, this is worse than v2 because then one bit is migrated and the
> other is not.

> I think v2 is correct and, on top of it, you have to check in post_load
> whether nc->link_down matches the loaded BMSR value.  If not, you need
> to either set the link status in NetClientState, or generate an
> RxUnderrun interrupt.


If correct link_down in rtl8139_post_load(), both v2 and v3 will work.

   s->nic->nc.link_down = (s->BasicModeStatus & 0x04) == 0;

s->BasicModeStatus is really migrated, s->nic->nc.link_down is inferred.
so I will continually work on v2.


> An alternative is to add a get_link_status callback and call it after
> migration for all NIC NetClientStates.
>
> Paolo

Thanks.

-- 
			Amos.