From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: "Toke Høiland-Jørgensen" <toke@redhat.com>
Cc: daniel@iogearbox.net, ast@fb.com, andrii@kernel.org,
bpf@vger.kernel.org, netdev@vger.kernel.org, brouer@redhat.com,
haliu@redhat.com, dsahern@gmail.com, jbenc@redhat.com
Subject: Re: [PATCH bpf-next] libbpf: Add libbpf_version() function to get library version at runtime
Date: Wed, 18 Nov 2020 09:43:25 -0800 [thread overview]
Message-ID: <20201118174325.zjomd2gvybof6awa@ast-mbp> (raw)
In-Reply-To: <20201118170738.324226-1-toke@redhat.com>
On Wed, Nov 18, 2020 at 06:07:38PM +0100, Toke Høiland-Jørgensen wrote:
> As a response to patches adding libbpf support to iproute2, an extensive
> discussion ensued about libbpf version visibility and enforcement in tools
> using the library[0]. In particular, two problems came to light:
>
> 1. If a tool is statically linked against libbpf, there is no way for a user
> to discover which version of libbpf the tool is using, unless the tool
> takes particular care to embed the library version at build time and print
> it.
>
> 2. If a tool is dynamically linked against libbpf, but doesn't use any
> symbols from the latest library version, the library version used at
> runtime can be older than the one used at compile time, and the
> application has no way to verify the version at runtime.
>
> To make progress on resolving this, let's add a libbpf_version() function that
> will simply return a version string which is embedded into the library at
> compile time. This makes it possible for applications to unambiguously get the
> library version at runtime, resolving (2.) above, and as an added bonus makes it
> easy for applications to print the library version, which should help with (1.).
>
> [0] https://lore.kernel.org/bpf/20201109070802.3638167-1-haliu@redhat.com/T/#t
>
> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Unless iproute2 adopts scrict libbpf.so.version == iproute2.version policy
and removes legacy bpf loader no iproute2 driven changes to libbpf will be accepted.
Just like the kernel doesn't add features for out-of-tree modules
libbpf doesn't add features for projects where libbpf is optional.
next prev parent reply other threads:[~2020-11-18 17:43 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-18 17:07 [PATCH bpf-next] libbpf: Add libbpf_version() function to get library version at runtime Toke Høiland-Jørgensen
2020-11-18 17:43 ` Alexei Starovoitov [this message]
2020-11-18 18:01 ` Toke Høiland-Jørgensen
2020-11-19 8:56 ` Jiri Benc
2020-11-18 21:16 ` David Ahern
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