Re: [dpdk-dev] [PATCH] vhost: change the vhost library to a common framework which can support more VIRTIO devices

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2016-09-13 20:58, Yuanhan Liu:
> rte_virtio_net.h is the header file will be exported for applications.
> Every change there would mean either an API or ABI breakage. Thus, we
> should try to avoid touching it. Don't even to say you added yet another
> header file, rte_virtio_dev.h.
> 
> I confess that the rte_virtio_net.h filename isn't that right: it sticks
> to virtio-net so tightly. We may could rename it to rte_vhost.h, but I
> doubt it's worthwhile: as said, it breaks the API.
> 
> The fortunate thing about this file is that, the context is actually not
> sticking to virtio-net too much. I mean, all the APIs are using the "vid",
> which is just a number. Well, except the virtio_net_device_ops() structure,
> which also should be renamed to vhost_device_ops(). Besides that, the
> three ops, "new_device", "destroy_device" and "vring_state_changed", are
> actually not limited to virtio-net device.
> 
> That is to say, we could have two options here:
> 
> - rename the header file and the structure properly, to not limited to
>   virtio-net
> 
> - live with it, let it be a legacy issue, and document it at somewhere,
>   say, "due to history reason, that virtio-net is the first one supported
>   in DPDK, we kept the header filename as rte_virtio_net.h, but not ..."
> 
> I personally would prefer the later one, which saves us from breaking
> applications again. I don't have strong objection to the first one though.
> 
> Thomas, any comments?

I don't think keeping broken names for historical reasons is a good
long term maintenance.
It could be a FIXME comment that we would fix when we have other reasons
to break the API.
However, in this case, it is easy to keep the compatibility, I think,
by including rte_virtio.h in rte_virtio_net.h.
Note: renames can also generally be managed with symlinks.

I also don't really understand why this file name is rte_virtio_net.h and
not rte_vhost_net.h.