Issue with parsing devargs syntax on Hyper-V platforms with DPDK-21.11

[madhukar mythri]

Hi,

On the Hyper-V(Azure) environment with/without Accelerated mode, we are
seeing segmentation-fault issues while running the secondary process of
DPDK with legacy syntax of arguments on DPDK-21.11 version.
Whereas the same arguments were working well till the DPDK-21.08 version,
only with the latest DPDK-21.11 this issue occurs.

Here is the EAL argument syntax to load 'net_failsafe' PMD:
   --vdev net_vdev_netvsc0,iface=s1p0 --block 032e:00:02.0

As per analysis on this, found that a new feature was introduced "Enabled
new devargs parser" in DPDK-21.11 version. As part of this new feature
found that this DPDK patch caused this issue:
https://patchwork.dpdk.org/project/dpdk/patch/1618283653-16510-6-git-send-email-xuemingl@nvidia.com/

When we remove this patch code, we do not see any issues with loading
primary/secondary processes. So, looks like an issue in identifying the new
global syntax and fallback to legacy syntax w.r.t to Hyper-V platforms.

Even we tried to give new syntax as mentioned in this patch to load this
"vdev" based bus as follows, but still seeing issues.
     -a bus=vdev,name=net_vdev_netvsc0/class=eth/driver=vdev_netvsc

Does the new syntax support the "vdev_netvsc"(Hyper-V) based PMD ? If so,
please let us know, the syntax on the same.

Thanks,
Madhukar.
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