mvebu: cannot load XDP

[DENG Qingfang]

Hi

On Fri, Jun 26, 2020 at 3:03 AM Jakov Petrina <jakov.petrina at sartura.hr> wrote:
>
> Hi Deng,
>
> On 25/06/2020 20:32, DENG Qingfang wrote:
> > Commit 76f9aa6f4bfd12fba34fc44aef890c48d4fb1024 should backport
> > support for mvneta XDP, but I can't load it.
> >
> > # ip link set dev eth0 xdp obj /tmp/bpf.o sec xdp1
> > RTNETLINK answers: Not supported
> >
> > strace output:
> >
> <snip>
> > recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0,
> > nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base={{len=132,
> > type=NLMSG_ERROR, flags=NLM_F_ACK_TLVS, seq=1593109321, pid=8909},
> > {error=-EOPNOTSUPP, msg={{len=52, type=RTM_NEWLINK,
> > flags=NLM_F_REQUEST|NLM_F_ACK, seq=1593109321, pid=0},
> > {ifi_family=AF_UNSPEC, ifi_type=ARPHRD_NETROM,
> > ifi_index=if_nametoindex("eth0"), ifi_flags=0, ifi_change=0},
> > {{nla_len=20, nla_type=IFLA_XDP}, [{{nla_len=8, nla_type=IFLA_XDP_FD},
> > 5}, {{nla_len=8, nla_type=IFLA_XDP_FLAGS},
> > XDP_FLAGS_UPDATE_IF_NOEXIST}]}}, {{nla_len=60,
> > nla_type=NLMSGERR_ATTR_MSG}, "mvneta: Hardware Buffer Manageme"...}}},
> > iov_len=32768}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) =
> > 132
>
> The rest of this output is due to upstream commit:
>
>      79572c98c554d mvneta driver disallow XDP program on hardware buffer
> management
>
> This check has not yet been reverted in mainline, so it would appear
> that XDP support in the mvneta driver is still limited to software
> buffer management only [1].
>
> [1] https://www.spinics.net/lists/netdev/msg626999.html
>
> There seems to be a `CONFIG_MVNETA_BM` kernel option which might be
> relevant for you.

Thanks. But I wonder about the performance penalty if I disable it..

>
> > writev(2, [{iov_base="RTNETLINK answers: Not supported"...,
> > iov_len=33}, {iov_base=NULL, iov_len=0}], 2RTNETLINK answers: Not
> > supported
> > ) = 33
> > exit_group(2)                           = ?
> > +++ exited with 2 +++
> >
> > xdpgeneric works fine.
> >
>
> Regards,
>
> --
> Jakov Petrina