From: Jiri Benc <jbenc@redhat.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: "David Ahern" <dsahern@gmail.com>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Andrii Nakryiko" <andrii.nakryiko@gmail.com>,
"Hangbin Liu" <haliu@redhat.com>,
"Stephen Hemminger" <stephen@networkplumber.org>,
"Alexei Starovoitov" <ast@kernel.org>,
"Martin KaFai Lau" <kafai@fb.com>,
"Song Liu" <songliubraving@fb.com>, "Yonghong Song" <yhs@fb.com>,
"David Miller" <davem@davemloft.net>,
"Jesper Dangaard Brouer" <brouer@redhat.com>,
Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
"Andrii Nakryiko" <andrii@kernel.org>,
"Toke Høiland-Jørgensen" <toke@redhat.com>
Subject: Re: [PATCHv3 iproute2-next 0/5] iproute2: add libbpf support
Date: Wed, 4 Nov 2020 10:28:16 +0100 [thread overview]
Message-ID: <20201104102816.472a9400@redhat.com> (raw)
In-Reply-To: <20201104024559.gxullc7e6boaupuk@ast-mbp.dhcp.thefacebook.com>
On Tue, 3 Nov 2020 18:45:59 -0800, Alexei Starovoitov wrote:
> libbpf is the only library I know that is backward and forward compatible.
This is great to hear. It means there will be no problem with iproute2
using the system libbpf. As libbpf is both backward and forward
compatible, iproute2 will just work with whatever version it is used
with.
> All other libraries are backwards compatible only.
Backward compatibility would be enough for iproute2 but forward
compatibility does not hurt, of course.
> The users can upgrade and downgrade libbpf version at any time.
> They can upgrade and downgrade kernel while keeping libbpf version the same.
> The users can upgrade llvm as well and libbpf has to expect unexpected
> and deal with all combinations.
This actually goes beyond what would be needed for iproute2 dynamically
linked against system libbpf.
> > How so? If libbpf is written against kernel APIs and properly versioned,
> > it should just work. A new version of libbpf changes the .so version, so
> > old commands will not load it.
>
> Please point out where do you see this happening in the patch set.
> See tools/lib/bpf/README.rst to understand the versioning.
If the iproute2 binaries are linked against a symbol of a newer version than
is available in the system libbpf (which should not really happen
unless the system is broken), the dynamic linker will refuse to load
it. If the binary is linked against an old version of a particular
symbol, that old version will be used, if it's still provided by the
library. Otherwise, it will not load. I don't see a problem here?
The only problem would be if a particular function changed its
semantics while retaining ABI. But since libbpf is backward and forward
compatible, this should not happen.
Jiri
next prev parent reply other threads:[~2020-11-04 9:28 UTC|newest]
Thread overview: 167+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-23 3:38 [PATCH iproute2-next 0/5] iproute2: add libbpf support Hangbin Liu
2020-10-23 3:38 ` [PATCH iproute2-next 1/5] configure: add check_libbpf() for later " Hangbin Liu
2020-10-23 3:38 ` [PATCH iproute2-next 2/5] lib: rename bpf.c to bpf_legacy.c Hangbin Liu
2020-10-23 3:38 ` [PATCH iproute2-next 3/5] lib: add libbpf support Hangbin Liu
2020-10-23 14:34 ` David Ahern
2020-10-25 15:13 ` Toke Høiland-Jørgensen
2020-10-25 22:12 ` David Ahern
2020-10-26 8:56 ` Hangbin Liu
2020-10-26 15:15 ` David Ahern
2020-10-27 2:58 ` Hangbin Liu
2020-10-24 0:21 ` Andrii Nakryiko
2020-10-25 15:11 ` Toke Høiland-Jørgensen
2020-10-26 8:10 ` Hangbin Liu
2020-10-23 3:38 ` [PATCH iproute2-next 4/5] examples/bpf: move struct bpf_elf_map defined maps to legacy folder Hangbin Liu
2020-10-23 3:38 ` [PATCH iproute2-next 5/5] examples/bpf: add bpf examples with BTF defined maps Hangbin Liu
2020-10-28 13:25 ` [PATCHv2 iproute2-next 0/5] iproute2: add libbpf support Hangbin Liu
2020-10-28 13:25 ` [PATCHv2 iproute2-next 1/5] configure: add check_libbpf() for later " Hangbin Liu
2020-10-28 13:25 ` [PATCHv2 iproute2-next 2/5] lib: rename bpf.c to bpf_legacy.c Hangbin Liu
2020-10-28 13:25 ` [PATCHv2 iproute2-next 3/5] lib: add libbpf support Hangbin Liu
2020-10-28 13:25 ` [PATCHv2 iproute2-next 4/5] examples/bpf: move struct bpf_elf_map defined maps to legacy folder Hangbin Liu
2020-10-28 13:25 ` [PATCHv2 iproute2-next 5/5] examples/bpf: add bpf examples with BTF defined maps Hangbin Liu
2020-10-28 21:17 ` [PATCHv2 iproute2-next 0/5] iproute2: add libbpf support Alexei Starovoitov
2020-10-28 23:02 ` David Ahern
2020-10-29 2:06 ` Hangbin Liu
2020-10-29 2:20 ` David Ahern
2020-10-29 2:45 ` Hangbin Liu
2020-10-29 3:00 ` David Ahern
2020-10-29 3:17 ` Hangbin Liu
2020-10-29 10:26 ` Hangbin Liu
2020-10-29 10:51 ` Toke Høiland-Jørgensen
2020-10-29 2:27 ` Andrii Nakryiko
2020-10-29 2:33 ` David Ahern
2020-10-29 2:46 ` Andrii Nakryiko
2020-10-29 2:34 ` Stephen Hemminger
2020-10-29 2:50 ` Andrii Nakryiko
2020-10-29 11:38 ` Jesper Dangaard Brouer
2020-10-29 20:30 ` Andrii Nakryiko
2020-10-29 2:33 ` Stephen Hemminger
2020-10-29 15:11 ` [PATCHv3 " Hangbin Liu
2020-10-29 15:11 ` [PATCHv3 iproute2-next 1/5] configure: add check_libbpf() for later " Hangbin Liu
2020-10-29 15:26 ` Toke Høiland-Jørgensen
2020-11-02 15:37 ` David Ahern
2020-11-03 5:54 ` Hangbin Liu
2020-11-03 17:32 ` David Ahern
2020-11-04 8:51 ` Hangbin Liu
2020-11-04 11:09 ` Toke Høiland-Jørgensen
2020-11-04 11:40 ` Hangbin Liu
2020-10-29 15:11 ` [PATCHv3 iproute2-next 2/5] lib: rename bpf.c to bpf_legacy.c Hangbin Liu
2020-10-29 15:11 ` [PATCHv3 iproute2-next 3/5] lib: add libbpf support Hangbin Liu
2020-11-02 15:41 ` David Ahern
2020-11-03 5:48 ` Hangbin Liu
2020-11-03 17:19 ` David Ahern
2020-11-04 8:22 ` Hangbin Liu
2020-11-05 2:33 ` David Ahern
2020-11-05 7:51 ` Hangbin Liu
2020-11-05 15:25 ` David Ahern
2020-11-05 15:57 ` Toke Høiland-Jørgensen
2020-11-05 16:02 ` David Ahern
2020-11-06 0:56 ` Hangbin Liu
2020-11-06 0:41 ` Hangbin Liu
2020-10-29 15:11 ` [PATCHv3 iproute2-next 4/5] examples/bpf: move struct bpf_elf_map defined maps to legacy folder Hangbin Liu
2020-10-29 15:11 ` [PATCHv3 iproute2-next 5/5] examples/bpf: add bpf examples with BTF defined maps Hangbin Liu
2020-11-02 15:47 ` [PATCHv3 iproute2-next 0/5] iproute2: add libbpf support David Ahern
2020-11-03 6:58 ` Andrii Nakryiko
2020-11-03 8:42 ` Jiri Benc
2020-11-03 17:45 ` David Ahern
2020-11-03 17:48 ` Alexei Starovoitov
2020-11-03 8:46 ` Daniel Borkmann
2020-11-03 17:35 ` David Ahern
2020-11-03 17:47 ` Alexei Starovoitov
2020-11-03 18:23 ` Stephen Hemminger
2020-11-03 22:32 ` David Ahern
2020-11-03 22:55 ` Alexei Starovoitov
2020-11-04 1:40 ` David Ahern
2020-11-04 2:45 ` Alexei Starovoitov
2020-11-04 9:28 ` Jiri Benc [this message]
2020-11-05 2:39 ` David Ahern
2020-11-04 2:17 ` Hangbin Liu
2020-11-04 3:11 ` Alexei Starovoitov
2020-11-04 10:01 ` Jiri Benc
2020-11-04 10:21 ` Daniel Borkmann
2020-11-04 11:20 ` Toke Høiland-Jørgensen
2020-11-04 13:12 ` Daniel Borkmann
2020-11-04 19:17 ` Jakub Kicinski
2020-11-04 20:43 ` Andrii Nakryiko
2020-11-04 22:24 ` Toke Høiland-Jørgensen
2020-11-05 20:14 ` Andrii Nakryiko
2020-11-05 3:48 ` David Ahern
2020-11-05 20:53 ` Andrii Nakryiko
2020-11-05 3:19 ` David Ahern
2020-11-05 14:05 ` Jamal Hadi Salim
2020-11-05 21:01 ` Andrii Nakryiko
2020-11-06 15:27 ` Jamal Hadi Salim
2020-11-06 21:25 ` Andrii Nakryiko
2020-11-10 12:47 ` Edward Cree
2020-11-11 0:53 ` Alexei Starovoitov
2020-11-11 11:31 ` Edward Cree
2020-11-11 18:08 ` Alexei Starovoitov
2020-11-05 20:45 ` Andrii Nakryiko
2020-11-06 9:00 ` Jiri Benc
2020-11-06 21:07 ` Andrii Nakryiko
2020-11-04 21:15 ` Edward Cree
2020-11-04 22:10 ` Alexei Starovoitov
2020-11-04 22:35 ` Toke Høiland-Jørgensen
2020-11-04 23:05 ` Edward Cree
2020-11-05 20:19 ` Andrii Nakryiko
2020-11-06 8:44 ` Jiri Benc
2020-11-06 20:57 ` Andrii Nakryiko
2020-11-06 21:04 ` Alexei Starovoitov
2020-11-06 23:25 ` Stephen Hemminger
2020-11-06 23:30 ` Andrii Nakryiko
2020-11-07 0:41 ` Stephen Hemminger
2020-11-07 1:07 ` Andrii Nakryiko
2020-11-06 23:38 ` David Ahern
2020-11-09 1:45 ` Alexei Starovoitov
2020-11-10 4:09 ` David Ahern
2020-11-11 0:47 ` Alexei Starovoitov
2020-11-11 11:02 ` Toke Høiland-Jørgensen
2020-11-11 15:06 ` Daniel Borkmann
2020-11-11 16:33 ` David Ahern
2020-11-12 22:36 ` Toke Høiland-Jørgensen
2020-11-12 23:20 ` Daniel Borkmann
2020-11-13 0:04 ` Stephen Hemminger
2020-11-13 0:40 ` Alexei Starovoitov
2020-11-13 3:55 ` David Ahern
2020-11-09 7:07 ` [PATCHv4 " Hangbin Liu
2020-11-09 7:07 ` [PATCHv4 iproute2-next 1/5] configure: add check_libbpf() for later " Hangbin Liu
2020-11-14 3:26 ` David Ahern
2020-11-16 4:30 ` Hangbin Liu
2020-11-16 4:33 ` David Ahern
2020-11-09 7:07 ` [PATCHv4 iproute2-next 2/5] lib: rename bpf.c to bpf_legacy.c Hangbin Liu
2020-11-14 3:24 ` David Ahern
2020-11-16 3:55 ` Hangbin Liu
2020-11-09 7:08 ` [PATCHv4 iproute2-next 3/5] lib: add libbpf support Hangbin Liu
2020-11-09 7:08 ` [PATCHv4 iproute2-next 4/5] examples/bpf: move struct bpf_elf_map defined maps to legacy folder Hangbin Liu
2020-11-09 7:08 ` [PATCHv4 iproute2-next 5/5] examples/bpf: add bpf examples with BTF defined maps Hangbin Liu
2020-11-16 6:53 ` [PATCHv5 iproute2-next 0/5] iproute2: add libbpf support Hangbin Liu
2020-11-16 6:53 ` [PATCHv5 iproute2-next 1/5] configure: add check_libbpf() for later " Hangbin Liu
2020-11-16 6:53 ` [PATCHv5 iproute2-next 2/5] lib: rename bpf.c to bpf_legacy.c Hangbin Liu
2020-11-16 6:53 ` [PATCHv5 iproute2-next 3/5] lib: add libbpf support Hangbin Liu
2020-11-16 6:53 ` [PATCHv5 iproute2-next 4/5] examples/bpf: move struct bpf_elf_map defined maps to legacy folder Hangbin Liu
2020-11-16 6:53 ` [PATCHv5 iproute2-next 5/5] examples/bpf: add bpf examples with BTF defined maps Hangbin Liu
2020-11-16 7:19 ` [PATCHv5 iproute2-next 0/5] iproute2: add libbpf support Alexei Starovoitov
2020-11-16 14:54 ` Jesper Dangaard Brouer
2020-11-16 23:29 ` Toke Høiland-Jørgensen
2020-11-17 2:37 ` Alexei Starovoitov
2020-11-17 3:19 ` Hangbin Liu
2020-11-17 18:27 ` Alexei Starovoitov
2020-11-17 11:56 ` Edward Cree
2020-11-17 3:38 ` David Ahern
2020-11-17 18:19 ` Alexei Starovoitov
2020-11-16 16:45 ` Stephen Hemminger
2020-11-23 13:11 ` [PATCHv6 " Hangbin Liu
2020-11-23 13:11 ` [PATCHv6 iproute2-next 1/5] iproute2: add check_libbpf() and get_libbpf_version() Hangbin Liu
2020-11-23 13:11 ` [PATCHv6 iproute2-next 2/5] lib: make ipvrf able to use libbpf and fix function name conflicts Hangbin Liu
2020-11-23 13:11 ` [PATCHv6 iproute2-next 3/5] lib: add libbpf support Hangbin Liu
2020-11-23 13:12 ` [PATCHv6 iproute2-next 4/5] examples/bpf: move struct bpf_elf_map defined maps to legacy folder Hangbin Liu
2020-11-23 13:12 ` [PATCHv6 iproute2-next 5/5] examples/bpf: add bpf examples with BTF defined maps Hangbin Liu
2020-11-25 5:28 ` [PATCHv6 iproute2-next 0/5] iproute2: add libbpf support David Ahern
2020-11-25 5:30 ` patchwork-bot+netdevbpf
2020-11-29 6:16 ` [PATCH " Stephen Hemminger
2020-11-29 6:22 ` Greg KH
2020-11-30 11:39 ` Michal Kubecek
2020-11-29 17:33 ` Alexei Starovoitov
2020-11-29 19:41 ` David Ahern
2020-11-30 11:04 ` Toke Høiland-Jørgensen
2020-12-01 14:22 ` Jesper Dangaard Brouer
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