From: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
To: John Fastabend <john.fastabend@gmail.com>
Cc: Lorenzo Bianconi <lorenzo@kernel.org>,
bpf@vger.kernel.org, netdev@vger.kernel.org, davem@davemloft.net,
kuba@kernel.org, ast@kernel.org, daniel@iogearbox.net,
shayagr@amazon.com, sameehj@amazon.com, dsahern@kernel.org,
brouer@redhat.com, echaudro@redhat.com, jasowang@redhat.com,
alexander.duyck@gmail.com, saeed@kernel.org,
maciej.fijalkowski@intel.com
Subject: Re: [PATCH v8 bpf-next 00/14] mvneta: introduce XDP multi-buffer support
Date: Fri, 9 Apr 2021 22:16:14 +0200 [thread overview]
Message-ID: <YHC2DlTAoxwKVR/m@lore-desk> (raw)
In-Reply-To: <606fa62f6fe99_c8b920884@john-XPS-13-9370.notmuch>
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> Lorenzo Bianconi wrote:
[...]
>
> I just read the commit messages for v8 so far. But, I'm still wondering how
> to handle use cases where we want to put extra bytes at the end of the
> packet, or really anywhere in the general case. We can extend tail with above
> is there anyway to then write into that extra space?
>
> I think most use cases will only want headers so we can likely make it
> a callout to a helper. Could we add something like, xdp_get_bytes(start, end)
> to pull in the bytes?
>
> My dumb pseudoprogram being something like,
>
> trailer[16] = {0,1,2,3,4,5,6,7,8,9,a,b,c,d,e}
> trailer_size = 16;
> old_end = xdp->length;
> new_end = xdp->length + trailer_size;
>
> err = bpf_xdp_adjust_tail(xdp, trailer_size)
> if (err) return err;
>
> err = xdp_get_bytes(xdp, old_end, new_end);
> if (err) return err;
>
> memcpy(xdp->data, trailer, trailer_size);
>
> Do you think that could work if we code up xdp_get_bytes()? Does the driver
> have enough context to adjust xdp to map to my get_bytes() call? I think
> so but we should check.
Hi John,
can you please give more details about how xdp_get_bytes() is expected to work?
iiuc trailer will be pulled at the beginning of the frame after updating the
xdp_buff with xdp_get_bytes helper, correct?
If so I guess it will doable, it is just a matter of reserve more space mapping
the buffer on the dma engine respect to XDP_PACKET_HEADROOM. If the frame does
not fit in a single buffer, it will be split over multiple buffers.
If you are referring to add trailer at the end of the buffer, I guess it is
doable as well introducing a bpf helper.
I guess both of the solutions are orthogonal to this series.
Regards,
Lorenzo
>
> >
> > More info about the main idea behind this approach can be found here [1][2].
>
> Thanks for working on this!
>
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next prev parent reply other threads:[~2021-04-09 20:16 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-08 12:50 [PATCH v8 bpf-next 00/14] mvneta: introduce XDP multi-buffer support Lorenzo Bianconi
2021-04-08 12:50 ` [PATCH v8 bpf-next 01/14] xdp: introduce mb in xdp_buff/xdp_frame Lorenzo Bianconi
2021-04-08 18:17 ` Vladimir Oltean
2021-04-09 16:03 ` Lorenzo Bianconi
2021-04-29 13:36 ` Jesper Dangaard Brouer
2021-04-29 13:54 ` Lorenzo Bianconi
2021-04-08 12:50 ` [PATCH v8 bpf-next 02/14] xdp: add xdp_shared_info data structure Lorenzo Bianconi
2021-04-08 13:39 ` Vladimir Oltean
2021-04-08 14:26 ` Lorenzo Bianconi
2021-04-08 18:06 ` kernel test robot
2021-04-08 12:50 ` [PATCH v8 bpf-next 03/14] net: mvneta: update mb bit before passing the xdp buffer to eBPF layer Lorenzo Bianconi
2021-04-08 18:19 ` Vladimir Oltean
2021-04-09 16:24 ` Lorenzo Bianconi
2021-04-08 12:50 ` [PATCH v8 bpf-next 04/14] xdp: add multi-buff support to xdp_return_{buff/frame} Lorenzo Bianconi
2021-04-08 18:30 ` Vladimir Oltean
2021-04-09 16:28 ` Lorenzo Bianconi
2021-04-08 12:50 ` [PATCH v8 bpf-next 05/14] net: mvneta: add multi buffer support to XDP_TX Lorenzo Bianconi
2021-04-08 18:40 ` Vladimir Oltean
2021-04-09 16:36 ` Lorenzo Bianconi
2021-04-08 12:50 ` [PATCH v8 bpf-next 06/14] net: mvneta: enable jumbo frames for XDP Lorenzo Bianconi
2021-04-08 12:50 ` [PATCH v8 bpf-next 07/14] net: xdp: add multi-buff support to xdp_build_skb_from_fram Lorenzo Bianconi
2021-04-08 12:51 ` [PATCH v8 bpf-next 08/14] bpf: add multi-buff support to the bpf_xdp_adjust_tail() API Lorenzo Bianconi
2021-04-08 19:15 ` Vladimir Oltean
2021-04-08 20:54 ` Vladimir Oltean
2021-04-09 18:13 ` Lorenzo Bianconi
2021-04-08 12:51 ` [PATCH v8 bpf-next 09/14] bpd: add multi-buffer support to xdp copy helpers Lorenzo Bianconi
2021-04-08 20:57 ` Vladimir Oltean
2021-04-09 18:19 ` Lorenzo Bianconi
2021-04-08 21:04 ` Vladimir Oltean
2021-04-14 8:08 ` Eelco Chaudron
2021-04-08 12:51 ` [PATCH v8 bpf-next 10/14] bpf: add new frame_length field to the XDP ctx Lorenzo Bianconi
2021-04-08 12:51 ` [PATCH v8 bpf-next 11/14] bpf: move user_size out of bpf_test_init Lorenzo Bianconi
2021-04-08 12:51 ` [PATCH v8 bpf-next 12/14] bpf: introduce multibuff support to bpf_prog_test_run_xdp() Lorenzo Bianconi
2021-04-08 12:51 ` [PATCH v8 bpf-next 13/14] bpf: test_run: add xdp_shared_info pointer in bpf_test_finish signature Lorenzo Bianconi
2021-04-08 12:51 ` [PATCH v8 bpf-next 14/14] bpf: update xdp_adjust_tail selftest to include multi-buffer Lorenzo Bianconi
2021-04-09 0:56 ` [PATCH v8 bpf-next 00/14] mvneta: introduce XDP multi-buffer support John Fastabend
2021-04-09 20:16 ` Lorenzo Bianconi [this message]
2021-04-13 15:16 ` Eelco Chaudron
2021-04-16 14:27 ` Magnus Karlsson
2021-04-16 21:29 ` Lorenzo Bianconi
2021-04-16 23:00 ` Daniel Borkmann
2021-04-18 16:18 ` Jesper Dangaard Brouer
2021-04-19 6:20 ` Magnus Karlsson
2021-04-19 6:55 ` Lorenzo Bianconi
2021-04-20 13:49 ` Magnus Karlsson
2021-04-21 12:47 ` Jesper Dangaard Brouer
2021-04-21 14:12 ` Magnus Karlsson
2021-04-21 15:39 ` Jesper Dangaard Brouer
2021-04-22 10:24 ` Magnus Karlsson
2021-04-22 14:42 ` Jesper Dangaard Brouer
2021-04-22 15:05 ` Crash for i40e on net-next (was: [PATCH v8 bpf-next 00/14] mvneta: introduce XDP multi-buffer support) Jesper Dangaard Brouer
2021-04-23 5:28 ` Magnus Karlsson
2021-04-23 16:43 ` Alexander Duyck
2021-04-25 9:45 ` Magnus Karlsson
2021-04-27 18:28 ` [PATCH v8 bpf-next 00/14] mvneta: introduce XDP multi-buffer support Lorenzo Bianconi
2021-04-28 7:41 ` Magnus Karlsson
2021-04-29 12:49 ` Jesper Dangaard Brouer
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