From: Florian Weimer <fweimer@redhat.com>
To: Szabolcs Nagy <Szabolcs.Nagy@arm.com>
Cc: David Kilroy <David.Kilroy@arm.com>, nd <nd@arm.com>,
"libc-alpha\@sourceware.org" <libc-alpha@sourceware.org>
Subject: Re: [PATCH 1/3] elf: Allow dlopen of filter object to work [BZ #16272]
Date: Tue, 22 Oct 2019 09:43:00 -0000 [thread overview]
Message-ID: <871rv5m7xu.fsf@oldenburg2.str.redhat.com> (raw)
In-Reply-To: <6cbb4c5e-72e0-507d-fa34-5a70db35c03a@arm.com> (Szabolcs Nagy's message of "Mon, 21 Oct 2019 16:42:16 +0000")
* Szabolcs Nagy:
> the scenario is:
>
> libA.so and libB.so export a set of symbols. this is abi
> and there are multiple providers of libA.so and libB.so.
>
> one provider wants to have a single libinternal.so that
> defines all the symbols of libA and libB as they share a
> lot of code.
>
> (1) having libA.so and libB.so as "wrapper libraries" around
> libinternal.so with RTLD_NEXT would work, but that's less
> efficient because of the extra indirection,
If libA.so and libB.so have libinternal.so as a DT_NEEDED dependency,
you do not need to implement forwarding with RTLD_NEXT.
> (3) symlinking libA.so and libB.so to libinternal.so makes
> all symbols visible when either of them is loaded, polluting
> the link namespace.
Filters do that as well. There is no actual per-symbol run-time
filtering implemented today, and it is unclear if Solaris implements it.
> (libinternal.so is a video driver lib and libA, libB, .. are
> various opengl libs with fixed abi)
Is there an expectation that libinternal interposes symbols in libA
etc., perhaps with more efficient implementations? And if not, a
fallback implementation in libA etc. is used? This is clearly not
supported by the Solaris filter feature (as documented).
Thanks,
Florian
next prev parent reply other threads:[~2019-10-22 9:43 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-17 10:33 [PATCH 0/3] " David Kilroy
2019-10-17 10:33 ` [PATCH 1/3] " David Kilroy
2019-10-18 11:43 ` Florian Weimer
2019-10-18 15:09 ` David Kilroy
2019-10-21 11:27 ` Florian Weimer
2019-10-21 14:12 ` David Kilroy
2019-10-21 14:21 ` Florian Weimer
2019-10-21 16:42 ` Szabolcs Nagy
2019-10-22 9:22 ` David Kilroy
2019-10-22 9:49 ` Florian Weimer
2019-10-22 11:20 ` David Kilroy
2019-10-22 9:43 ` Florian Weimer [this message]
2019-10-22 11:18 ` David Kilroy
2019-10-22 11:22 ` Florian Weimer
2019-10-22 11:27 ` David Kilroy
2019-10-22 11:31 ` Florian Weimer
2019-10-22 8:28 ` David Kilroy
2019-10-22 8:36 ` Florian Weimer
2019-10-22 9:39 ` David Kilroy
2019-10-22 9:57 ` Florian Weimer
2019-10-22 11:24 ` David Kilroy
2019-10-22 14:29 ` David Kilroy
2019-10-17 10:33 ` [PATCH 3/3] elf: avoid stack allocation in dl_open_worker David Kilroy
2019-10-17 10:33 ` [PATCH 2/3] elf: avoid redundant sort in dlopen David Kilroy
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