Re: Cannot load eBPF program as XDP

[Jesper Dangaard Brouer <brouer@redhat.com>]

On Thu, 29 Jun 2017 02:19:57 +0200
Daniel Borkmann <daniel@iogearbox.net> wrote:

> On 06/29/2017 12:40 AM, MD I. Islam wrote:
> > On Wed, Jun 28, 2017 at 5:04 AM, Daniel Borkmann <daniel@iogearbox.net> wrote:  
> >> On 06/28/2017 04:32 AM, MD I. Islam wrote:  
> >>> On Tue, Jun 27, 2017 at 10:05 PM, Y Song <ys114321@gmail.com> wrote:  
> >>>>
> >>>> xdp meta data is different:
> >>>>
> >>>> struct xdp_md {
> >>>>           __u32 data;
> >>>>           __u32 data_end;
> >>>> };
> >>>>
> >>>> All other fields available for skb metadata won't be available in XDP.
> >>>> That is way
> >>>> you get verification failure.  
> >>>
> >>> Thanks for the quick reply! Now I'm trying xdp1_kern.c which uses
> >>> xdp_md. Now I'm getting the error:
> >>>
> >>> Note: 8 bytes struct bpf_elf_map fixup performed due to size mismatch!  
> >>
> >> This one is harmless, just telling you that the native bpf_elf_map
> >> from iproute2 is different than the one you're loading, so it fixes
> >> up the remaining 8 bytes automatically.
> >>  
> >>> RTNETLINK answers: Operation not supported  
> >>
> >> This one seems likely that the driver you're trying to attach this to
> >> does not have XDP support. What's the driver you're using?  
> >
> > Yes, I was using RTL8111 driver which doesn't support XDP. I will
> > eventually use Netronome NIC which will hopefully work.
> >
> > I'm facing the same problem in Mininet. Is there a way to use XDP in
> > Mininet? I am using Linux router in Mininet and I want to attach XDP
> > programs to virtual interfaces.  
> 
> You can use generic XDP, which will load also with drivers not
> supporting XDP natively (the fallback to generic XDP is transparent).
> It's part of 4.12 kernel.

Yes, exactly. With kernel 4.12 you can develop your XDP program, before
you get your hands on a NIC what have implemented the XDP eBPF-hook.

It is slower, compared here:
https://prototype-kernel.readthedocs.io/en/latest/blogposts/xdp25_eval_generic_xdp_tx.html

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer