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From: | Anthony Liguori |
Subject: | Re: [Qemu-devel] Hitting 29 NIC limit |
Date: | Thu, 14 Oct 2010 07:59:00 -0500 |
User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.12) Gecko/20100915 Lightning/1.0b1 Thunderbird/3.0.8 |
On 10/14/2010 07:36 AM, Markus Armbruster wrote:
Avi Kivity<address@hidden> writes:On 10/14/2010 12:54 AM, Anthony Liguori wrote: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.I'm amazed that works. Can't see how creating another qdev in the same slot makes a proper multifunction device.
multifunction=on sets the multifunction bit for the PCI device. Then it's a matter of setting the address to be a specific function.
Our default platform devices are actually multifunction.
This is unlikely to work right wrt pci hotplug. If we want to support a large number of interfaces, we need true multiport cards.Indeed. As far as I know, we can't hot plug multifunction PCI devices.
Yup. Regards, Anthony Liguori
What's the motivation for such a huge number of interfaces?-- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to address@hidden More majordomo info at http://vger.kernel.org/majordomo-info.html
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