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From:   Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Wed, 21 Oct 2020 11:43:08 +0200
Message-ID: <CAMuHMdW=1LfE8UoGRVBvrvrintQMNKUdTe5PPQz=PN3=gJmw=Q@mail.gmail.com>
Subject: Re: [PATCH] mptcp: MPTCP_IPV6 should depend on IPV6 instead of
 selecting it
To:     Jakub Kicinski <kuba@kernel.org>
Cc:     Matthieu Baerts <matthieu.baerts@tessares.net>,
        Mat Martineau <mathew.j.martineau@linux.intel.com>,
        "David S . Miller" <davem@davemloft.net>,
        Florian Westphal <fw@strlen.de>,
        Peter Krystad <peter.krystad@linux.intel.com>,
        netdev <netdev@vger.kernel.org>, mptcp@lists.01.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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Hi Jakub,

On Wed, Oct 21, 2020 at 5:56 AM Jakub Kicinski <kuba@kernel.org> wrote:
> On Tue, 20 Oct 2020 11:26:34 +0200 Matthieu Baerts wrote:
> > On 20/10/2020 09:38, Geert Uytterhoeven wrote:
> > > MPTCP_IPV6 selects IPV6, thus enabling an optional feature the user may
> > > not want to enable.  Fix this by making MPTCP_IPV6 depend on IPV6, like
> > > is done for all other IPv6 features.
> >
> > Here again, the intension was to select IPv6 from MPTCP but I understand
> > the issue: if we enable MPTCP, we will select IPV6 as well by default.
> > Maybe not what we want on some embedded devices with very limited memory
> > where IPV6 is already off. We should instead enable MPTCP_IPV6 only if
> > IPV6=y. LGTM then!
> >
> > Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
>
> Applied, thanks!

My apologies, this fails for the CONFIG_IPV6=m and CONFIG_MPTCP=y
case:
  + error: net/mptcp/protocol.o: undefined reference to
`inet6_getname':  => .rodata+0x19c)
  + error: net/mptcp/protocol.o: undefined reference to `inet6_ioctl':
 => .rodata+0x1a4)
  + error: net/mptcp/protocol.o: undefined reference to
`inet6_recvmsg':  => .rodata+0x1c4)
  + error: net/mptcp/protocol.o: undefined reference to
`inet6_release':  => .rodata+0x188)
  + error: net/mptcp/protocol.o: undefined reference to
`inet6_sendmsg':  => .rodata+0x1c0)
  + error: protocol.c: undefined reference to `inet6_destroy_sock':
=> .text+0x4994)
  + error: protocol.c: undefined reference to
`inet6_register_protosw':  => .init.text+0xc6)
  + error: protocol.c: undefined reference to `inet6_stream_ops':  =>
.text+0x2bb0)
  + error: protocol.c: undefined reference to `tcpv6_prot':  => .text+0x2ba8)
  + error: subflow.c: undefined reference to
`tcp_request_sock_ipv6_ops':  => .text+0x8e2)
  + error: undefined reference to `ipv6_specific':  => (.init.text+0xea)
  + error: undefined reference to `tcp_request_sock_ipv6_ops':  =>
(.init.text+0xc4)

So those issues have to be fixed first

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds