Adding in support for Azure Netvsc.

[HackTheMak]

Adding in support for Azure Netvsc.

[vmaffione]

There are two approaches.
The first (and probably easier/preferred) one is the "external drivers" one, where basically netmap downloads the original source code from the Internet (for a given version), patches it and compiles the patched kernel module.
You will need

1. A netmap patch. For virtio_net the patch is is https://github.com/luigirizzo/netmap/blob/master/LINUX/final-patches/custom--virtio_net.c--4.9
2. Netmap support header. FOr virtio_net the header is https://github.com/luigirizzo/netmap/blob/master/LINUX/if_virtio_net_netmap.h
3. Modifications to the build system, e.g. https://github.com/luigirizzo/netmap/blob/master/LINUX/configure and https://github.com/luigirizzo/netmap/blob/master/LINUX/default-config.mak.in_ (but I'm not able to give more details on this)

The second approach is using the sources from the running kernel, and still ofc applying a patch. The problem is that there are so many versions of the driver that you need to prepare many patches, and this is complex. Also, for the case of virtio-net the driver evolves very quickly, so that the problem becomes even worse.

[HackTheMak]

Ok, thanks for replying.
So in theory, in simplest terms, is to use the Virtio files as listed above as templates for the Azure NICs. Then modify the build systems files as above.

[HackTheMak]

Would it be possible to use the AWS ENA files as a reference to the modify the Azure MANA files? This avoids modifying the Netmap files from the looks of it. The reason asking of this, is that for FreeBSD, the ENA files have Netmap coding within them, thus allows Netmap to support ENA. I assume that would be the second approach method that was mentioned.
Example:
AWS ENA Files: https://github.com/freebsd/freebsd-src/tree/main/sys/dev/ena
MS MANA Files: https://github.com/freebsd/freebsd-src/tree/main/sys/dev/mana

[vmaffione]

It is possibile. And yes, that would be the second approach. I thought you wanted to work on Linux, so my answer was set on this assumption.
If you want to add netmap support for FreeBSD, instead, then it's actually easier. You can just submit a patch to the FreeBSD project (changes to the MANA driver plus the MANA netmap header implementing txsync/rxsync and the other netmap callbacks.