Re: Building fastnetmon on mipsel

Hello!

Thank you so much for your feedback!

Yep, that's actually what we're trying to do.

My code looks like:
__atomic_add_fetch(&total_simple_packets_processed, 1, __ATOMIC_RELAXED);

Full link to code:
https://github.com/pavel-odintsov/fastnetmon/blob/master/src/fastnetmon_logic.cpp#L2675

And we try to explicitly link with -latomic and cmake does right thing by
adding -atomic:
/usr/bin/c++ -g -O2 -ffile-prefix-map=/<<PKGBUILDDIR>>=.
-fstack-protector-strong -Wformat -Werror=format-security ..... -o
fastnetmon  -latomic

But liker fails to link it to atomic due to missing function call:
/usr/bin/ld: libfastnetmon_logic.a(fastnetmon_logic.cpp.o): undefined
reference to symbol '__atomic_fetch_add_8@@LIBATOMIC_1.0'

We do not call __atomic_fetch_add_8 directly, it's just how lineker sees
it.

On Thu, 5 May 2022 at 15:44, Jeffrey Walton <[email protected]> wrote:

> > -- Looking for __sync_fetch_and_add_8 in atomic
> > -- Looking for __sync_fetch_and_add_8 in atomic - not found
>
> I hit this a long time ago in a non-CMake project. If memory serves me
> correctly...
>
> According to Jakub Jelinek, you should use the GCC builtin and link to
> libatomic. GCC will emulate the missing primitive through the builtin.
> Instead of using __atomic_fetch_add_8 directly, use
> __atomic_fetch_add.
>
> Also see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56296#c1 and
> https://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html .
>
> Jeff
>
> On Thu, May 5, 2022 at 7:54 AM Patrick Matthäi <[email protected]>
> wrote:
> >
> > Hello mips(el) porters,
> >
> > (please CC us, we are not subscribed).
> >
> > We are trying to build fastnetmon on mipsel, without success. Maybe you
> can help us on fixing this?:
> >
> > /usr/bin/c++ -g -O2 -ffile-prefix-map=/<<PKGBUILDDIR>>=.
> -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time
> -D_FORTIFY_SOURCE=2 -Wl,-z,relro -Wl,-z,now -rdynamic
> CMakeFiles/fastnetmon.dir/fastnetmon.cpp.o -o fastnetmon  -latomic
> libgraphite_metrics.a libinfluxdb_metrics.a -lgpr -lgrpc++ -lgrpc
> libfastnetmon_grpc_pb_cc.a libfastnetmon_pb_cc.a -lprotobuf -lhiredis
> -lmongoc-1.0 -lbson-1.0 -llog4cpp -lpthread libpatricia.a
> libfastnetmon_pcap_format.a libipfix_rfc.a libfast_library.a
> libunified_parser.a -lssl -lcrypto libgobgp_action.a libexabgp_action.a
> libafpacket_plugin.a libsflow_plugin.a libnetflow_plugin.a libpcap_plugin.a
> libexample_plugin.a libfastnetmon_logic.a
> /usr/lib/mipsel-linux-gnu/libboost_thread.so.1.74.0
> /usr/lib/mipsel-linux-gnu/libboost_atomic.so.1.74.0 -lpthread
> /usr/lib/mipsel-linux-gnu/libboost_regex.so.1.74.0
> /usr/lib/mipsel-linux-gnu/libboost_program_options.so.1.74.0
> /usr/lib/mipsel-linux-gnu/libboost_system.so.1.74.0 libpatricia.a
> libfastnetmon_pcap_format.a libsimple_packet_capnp.a -lcapnp -lkj -ljson-c
> -lssl -lcrypto -lgpr -lgrpc++ -lgrpc -lprotobuf libgobgp_api_client_pb_cc.a
> libgobgp_api_client_grpc_pb_cc.a libattribute_pb_cc.a libunified_parser.a
> libfastnetmon_packet_parser.a libsimple_packet_parser_ng.a
> libnetwork_data_structures.a liblibsflow.a libipfix_rfc.a libnetflow.a
> -lpcap -lhiredis -lmongoc-1.0 -lbson-1.0 libexabgp_action.a
> libbgp_protocol.a
> > /usr/bin/ld: libfastnetmon_logic.a(fastnetmon_logic.cpp.o): undefined
> reference to symbol '__atomic_fetch_add_8@@LIBATOMIC_1.0'
> > /usr/bin/ld: /usr/lib/gcc/mipsel-linux-gnu/11/libatomic.so: error adding
> symbols: DSO missing from command line
> >
> > -------- Weitergeleitete Nachricht --------
> > Betreff: Re: GoBGP and FastNetMon on Debian
> > Datum: Thu, 5 May 2022 11:33:33 +0100
> > Von: Pavel Odintsov <[email protected]>
> > An: Patrick Matthäi <[email protected]>
> >
> > Hello!
> >
> > That's extremely strange indeed.
> >
> > Cmake claims that library is here:
> >
> > -- Performing Test HAVE__ATOMIC_ADD_FETCH - Failed
> > -- We have no __atomic_add_fetch, will try linking with libatomic
> > -- Looking for __atomic_add_fetch_8 in atomic
> > -- Looking for __atomic_add_fetch_8 in atomic - found
> > -- Linked with atomic library
> > -- Performing Test HAVE__SYNC_FETCH_AND_ADD
> > -- Performing Test HAVE__SYNC_FETCH_AND_ADD - Failed
> > -- We have no __sync_fetch_and_add on this platform, will try linking
> with libatomic
> > -- Looking for __sync_fetch_and_add_8 in atomic
> > -- Looking for __sync_fetch_and_add_8 in atomic - not found
> > -- We have no support for __sync_fetch_and_add in atomic library, skip
> linking
> >
> > Do you have ssh access to any machine with this such architecture?
> >
> > On Thu, 5 May 2022 at 10:37, Patrick Matthäi <[email protected]>
> wrote:
> >>
> >> Hey,
> >>
> >> hmpf, I hate mipsel..
> >>
> https://buildd.debian.org/status/fetch.php?pkg=fastnetmon&arch=mipsel&ver=1.2.0%2Bgit20220505-1&stamp=1651743326&raw=0
> >>
> >> Am 05.05.2022 um 02:14 schrieb Pavel Odintsov:
> >>
> >> Good morning!
> >>
> >> I hope you liked your movie yesterday.
> >>
> >> I did my side of task and resurrected logic which uses
> __atomic_add_fetch instead of __sync_fetch_and_add:
> https://github.com/pavel-odintsov/fastnetmon/commit/dad1c7b0b9fe16d24566649aa92d757050f4ec2a
> >>
> >> Good news that we have it in place for Debian build for multiple
> platforms we had issues previously:
> https://salsa.debian.org/debian/fastnetmon/-/blob/master/debian/rules#L11
> >>
> >> Please keep me updated about mipsel builds.
> >>
> >> We have some work to get rid of atomic increments and replace them by
> locks and I hope we will drop this magic in coming releases.
> >>
> >>
> >> On Wed, 4 May 2022 at 18:54, Pavel Odintsov <[email protected]>
> wrote:
> >>>
> >>> Hello!
> >>>
> >>> Excellent!
> >>>
> >>> Have a great evening!
> >>>
> >>> On Wed, 4 May 2022 at 18:54, Patrick Matthäi <[email protected]>
> wrote:
> >>>>
> >>>> Yes i will try tomorrow, now i Went to the Cinema :)
> >>>>
> >>>> Am 04.05.2022 19:45 schrieb Pavel Odintsov <[email protected]
> >:
> >>>>
> >>>> Hello!
> >>>>
> >>>> It may be really fun but I even had fix for it back in time:
> https://github.com/pavel-odintsov/fastnetmon/commit/d5711bb3da43bff3f90a33c5d5ab9b5a262660c5
> >>>>
> >>>> I think it was removed during one of many code refactorings from
> previous years.
> >>>>
> >>>> I'll return this logic back shortly.
> >>>>
> >>>> Is it possible to set flag cmake .. -DUSE_NEW_ATOMIC_BUILTINS=ON only
> for mipsel targets? I'm not 100% sure about this patch to enable it for all
> platforms.
> >>>>
> >>>> Thank you!
> >>>>
> >>>> On Wed, 4 May 2022 at 18:41, Pavel Odintsov <[email protected]>
> wrote:
> >>>>
> >>>> Hello!
> >>>>
> >>>> Oh, sad stuff indeed.
> >>>>
> >>>> -- Will use new memory model aware atomic builtins
> >>>> -- Performing Test HAVE__ATOMIC_ADD_FETCH
> >>>> -- Performing Test HAVE__ATOMIC_ADD_FETCH - Failed
> >>>> -- We have no __atomic_add_fetch, will try linking with libatomic
> >>>> -- Looking for __atomic_add_fetch_8 in atomic
> >>>> -- Looking for __atomic_add_fetch_8 in atomic - found
> >>>> -- Linked with atomic library
> >>>> -- Performing Test HAVE__SYNC_FETCH_AND_ADD
> >>>> -- Performing Test HAVE__SYNC_FETCH_AND_ADD - Failed
> >>>> -- We have no __sync_fetch_and_add on this platform, will try linking
> with libatomic
> >>>> -- Looking for __sync_fetch_and_add_8 in atomic
> >>>> -- Looking for __sync_fetch_and_add_8 in atomic - not found
> >>>> -- We have no support for __sync_fetch_and_add in atomic library,
> skip linking
> >>>>
> >>>> We actually linked with libatomic for __atomic_add_fetch but it looks
> like __sync_fetch_and_add_8 is missing from libatomic.
> >>>>
> >>>> But I found something in Debian's bug tracker:
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=869805 which is quite
> insightful about this exact issue.
> >>>>
> >>>> On Wed, 4 May 2022 at 18:17, Patrick Matthäi <[email protected]>
> wrote:
> >>>>
> >>>>
> https://buildd.debian.org/status/fetch.php?pkg=fastnetmon&arch=mipsel&ver=1.2.0%2Bgit20220504-1&stamp=1651682939&raw=0
> >>>>
> >>>> Does not work :/ But I see the -latomic humpf..
> >>>>
> >>>> Am 04.05.2022 um 14:49 schrieb Pavel Odintsov:
> >>>>
> >>>> Hello!
> >>>>
> >>>> Thank you for feedback.
> >>>>
> >>>> I added some logic to fix it or at least confirm root cause of this
> issue with atomic:
> >>>>
> https://github.com/pavel-odintsov/fastnetmon/commit/89e8923759175a104aa491d4d0b683d627088110
> >>>>
> >>>> Would you mind adding this patch and trying build again?
> >>>>
> >>>> Thank you!
> >>>>
> >>>> On Tue, 3 May 2022 at 19:18, Patrick Matthäi <[email protected]>
> wrote:
> >
> >
>


-- 
Sincerely yours, Pavel Odintsov