Re: [dpdk-dev] [PATCH 0/4] Introduce IF proxy library

[Stephen Hemminger <stephen@networkplumber.org>]

On Fri, 6 Mar 2020 17:41:00 +0100
Andrzej Ostruszka <aostruszka@marvell.com> wrote:

> What is this useful for
> =======================
> 
> Usually, when an ethernet port is assigned to DPDK it vanishes from the
> system and user looses ability to control it via normal configuration
> utilities (e.g. those from iproute2 package).  Moreover by default DPDK
> application is not aware of the network configuration of the system.
> 
> To address both of these issues application needs to:
> - add some command line interface (or other mechanism) allowing for
>   control of the port and its configuration
> - query the status of network configuration and monitor its changes
> 
> The purpose of this library is to help with both of these tasks (as long
> as they remain in domain of configuration available to the system).  In
> other words, if DPDK application has some special needs, that cannot be
> addressed by the normal system configuration utilities, then they need
> to be solved by the application itself.
> 
> The connection between DPDK and system is based on the existence of
> ports that are visible to both DPDK and system (like Tap, KNI and
> possibly some other drivers).  These ports serve as an interface
> proxies.
> 
> Let's visualize the action of the library by the following example:
> 
>               Linux             |            DPDK
> ==============================================================
>                                 |
>                                 |   +-------+       +-------+
>                                 |   | Port1 |       | Port2 |
> "ip link set dev tap1 mtu 1600" |   +-------+       +-------+
>                           |     |       ^              ^ ^
>                           |  +------+   | mtu_change   | |
>                           `->| Tap1 |---' callback     | |
>                              +------+                  | |
> "ip addr add 198.51.100.14 \    |                      | |
>                   dev tap2"     |                      | |
>                           |  +------+                  | |
>                           +->| Tap2 |------------------' |
>                           |  +------+  addr_add callback |
> "ip route add 198.0.2.0/24 \    |  |                     |
>                   dev tap2"     |  | route_add callback  |
>                                 |  `---------------------'

Has anyone investigated solving this in the kernel rather than
creating the added overhead of more Linux devices?

What I am thinking of is a netlink to userspace interface.
The kernel already has File-System-in-Userspace (FUSE) to allow
for filesystems. What about having a NUSE (Netlink in userspace)?

Then DPDK could have a daemon that is a provider to NUSE.
This solution would also benefit other non-DPDK projects like VPP
and allow DPDK to integrate with devlink etc.