From mboxrd@z Thu Jan  1 00:00:00 1970
From: Anthony Liguori <anthony@codemonkey.ws>
Subject: Re: [Qemu-devel] Hitting 29 NIC limit
Date: Wed, 13 Oct 2010 17:54:02 -0500
Message-ID: <4CB6388A.30006@codemonkey.ws>
References: <C8DB8174.2FEBC%anjali@juniper.net>
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Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
To: Anjali Kulkarni <anjali@juniper.net>
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On 10/13/2010 05:32 PM, Anjali Kulkarni wrote:
>
> Hi,
>
> Using the legacy way of starting up NICs, I am hitting a limitation after 29
> NICs ie no more than 29 are detected (that's because of the 32 PCI slot
> limit on a single bus- 3 are already taken up)
> I had initially increased the MAX_NICS to 48, just on my tree, to get to
> more, but ofcource that wont work.
> Is there any way to go beyond 29 NICs the legacy way?  What is the maximum
> that can be supported by the qdev mothod?
>    

I got up to 104 without trying very hard using the following script:

args=""
for slot in 5 6 7 8 9 10 11 12 13 14 15 16 17; do
for fn in 0 1 2 3 4 5 6 7; do
     args="$args -netdev user,id=eth${slot}_${fn}"
     args="$args -device 
virtio-net-pci,addr=${slot}.${fn},netdev=eth${slot}_${fn},multifunction=on,romfile="
done
done

x86_64-softmmu/qemu-system-x86_64 -hda ~/images/linux.img ${args} 
-enable-kvm

The key is to make the virtio-net devices multifunction and to fill out 
all 8 functions for each slot.

Regards,

Anthony Liguori

> Thanks
> Anjali
>
>
>