[Oisf-devel] Best userspace programming API for XDP features query to kernel?

[Michał Purzyński]

Extending the ethtools mechanism seems like a clean solution here. It is, by design, a 50% reporting tool and the XDP feature set would be just yet another feature here.

> On Apr 4, 2018, at 5:28 AM, Jesper Dangaard Brouer <brouer at redhat.com> wrote:
> 
> Hi Suricata people,
> 
> When Eric Leblond (and I helped) integrated XDP in Suricata, we ran
> into the issue, that at Suricata load/start time, we cannot determine
> if the chosen XDP config options, like xdp-cpu-redirect[1], is valid on
> this HW (e.g require driver XDP_REDIRECT support and bpf cpumap).
> 
> We would have liked a way to report that suricata.yaml config was
> invalid for this hardware/setup.  Now, it just loads, and packets gets
> silently dropped by XDP (well a WARN_ONCE and catchable via tracepoints).
> 
> My question to suricata developers: (Q1) Do you already have code that
> query the kernel or drivers for features?
> 
> 
> At the IOvisor call (2 weeks ago), we discussed two options of exposing
> XDP features avail in a given driver.
> 
> Option#1: Extend existing ethtool -k/-K "offload and other features"
> with some XDP features, that userspace can query. (Do you already query
> offloads, regarding Q1)
> 
> Option#2: Invent a new 'ip link set xdp' netlink msg with a query option.
> 
> (Q2) Do Suricata devs have any preference (or other options/ideas) for
> the way the kernel expose this info to userspace?
> 
> 
> 
> [1] http://suricata.readthedocs.io/en/latest/capture-hardware/ebpf-xdp.html#the-xdp-cpu-redirect-case
> -- 
> Best regards,
>  Jesper Dangaard Brouer
>  MSc.CS, Principal Kernel Engineer at Red Hat
>  LinkedIn: http://www.linkedin.com/in/brouer
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