Hello Ashhad,

It would be good to know what type of use case you have in mind for transferring data between user and kernel space, then perhaps I can answer more accurately.

For instance, if using the KPROBE program type, it is possible to use a BPF program as a filter of events that are later accessible through mmap, see "MMAP layout" in http://man7.org/linux/man-pages/man2/perf_event_open.2.html.

Or, if using a SOCKET type, the BPF program works as it does traditionally with tcpdump, to filter packets into a socket. A userspace program can listen on said socket.

For the SCHED_ACT and SCHED_CLS types, the BPF program can use a helper function to clone or redirect a packet to an ifindex of its choosing.

Please let me know which of these categories you are interested in.

Thanks,

Brenden Blanco

On Tue, Sep 22, 2015 at 4:57 AM, Ashhad Sheikh via iovisor-dev <iovisor-dev@...> wrote:

Hello, I am Ashhad. A CS major undergraduate student. I am researching on iOVISOR, specifically on it's real life performance.

I want to ask that Is it possible to have netlink communication between eBPF code and userspace --- if so how? I want to see if user space programs can communicate with eBPF beyond polling shared maps or not.
Waiting for a helpful response

Regards

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