[dpdk-dev] VMware Fusion + DPDK and KNI

Jay Rolette rolette at infiniteio.com
Mon Aug 18 20:16:24 CEST 2014

Thought I'd put this out there in case anyone else runs into it.

Using DPDK 1.6 on Ubuntu 14.04 LTS in a hardware appliance. Also using KNI
to share the data ports with an app that needs a normal TCP/IP stack

We had everything working reasonably well on the hardware, but most of our
developers run their code in a VM on their laptops: OS X (Mavericks) +
VMware Fusion 6 Pro.

On some VMs, we were getting errors trying to configure KNI ports:

$ sudo ifconfig ffEth0 netmask up
SIOCSIFFLAGS: Timer expired
SIOCSIFFLAGS: Timer expired

Skipping the "fun" involved with trying to track down the problem, here's
what ended up fixing it.

We had 4 network ports on the VM:

   - eth0 - Management port
   - eth1 - "other" function not related to the problem
   - eth2 & eth3 - inline datapath (bump-in-the-wire), but also KNI mapped
   to ffEth0 & ffEth1 by our DPDK app

If eth2 and eth3 are on the same vmnet, you'll get the "SIOCSIFFLAGS: Timer
expired" errors. Depending on what parameters you try to set, ifconfig may
think some of them have taken effect (they haven't) or it won't (setting
the MTU, etc.).

If you put eth2 and eth3 on separate vmnets, then no issues and you can
configure the KNI ports via ifconfig as expected.

No idea why having the ports on the same vmnet matters, since our app
doesn't care, but I haven't gone spelunking through the KNI source to find
the root cause.

Doubtful this will matter to many (any?), but maybe it'll save someone some

Jay Rolette
*infinite io*

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