From: "Ludovic Courtès" <ludo@gnu.org>
To: Farid Zakaria <fmzakari@ucsc.edu>
Cc: guix-devel@gnu.org, "Scogland, Tom" <scogland1@llnl.gov>,
Carlos Maltzahn <carlosm@ucsc.edu>
Subject: Re: Alternative solution to stat storm problem
Date: Tue, 18 Jan 2022 14:56:37 +0100 [thread overview]
Message-ID: <87k0exi1uy.fsf@gnu.org> (raw)
In-Reply-To: <CAH4OOv4ciWALemOF6vdVN4T_3M_uwMgRzFSTPHiut=xSWzhFxw@mail.gmail.com> (Farid Zakaria's message of "Sat, 8 Jan 2022 19:00:49 -0800")
Hi Farid,
Farid Zakaria <fmzakari@ucsc.edu> skribis:
[...]
>> I guess the advantage is that you don’t need the ld.so patch. The
>> downside is that PatchELF needs to be able to write longer NEEDED
>> strings in the dynamic section, which it may not always be successful at
>> (I think?).
>
> I can't claim to be a ELF specification guru but I have not
> encountered that longer NEEDED strings to be a cause for failure.
> The emacs example is a pretty good test case because the transitive
> closure of all NEEDED libraries is quite large, which all seem to be
> added successfully to the ELF header.
Well, we’d need a closer look, but I think PatchELF may need to enlarge
the relevant string table, and that may not always be possible.
> The benefit to me seems:
> 1 - does not need a glibc patch for functionality (although for other
> libc such as musl it might in this case
> https://www.openwall.com/lists/musl/2021/12/21/1)
> 2 - understanding the dependencies of an application become simpler
> 3 - there are esoteric cases where in fact libraries might link to the
> wrong libraries (although they are correct at build time) given a
> RUNPATH/RPATH since there are subtleties with the inheritance model.
>
> I'm actually researching ways to improve (3) as well through
> mentorship with Tom Scogland by researching alternative ways to do
> linking:
> - RUNPATH per NEEDED
> - the ability to specify whether a RUNPATH should be inherited or not
> to downstream dependencies
OK.
>> Also, I wonder if the absolute file names in NEEDED interfere with uses
>> of $LD_LIBRARY_PATH (making it impossible to force use of another
>> libxyz.so than the one that would be found in RUNPATH.)
>
> Correct. For a system with reproducibility in mind this can perhaps be
> a desired feature.
> It is the current limitation of the proposal.
I think it’s still useful to allow users to bypass normal mechanisms, be
it via LD_LIBRARY_PATH or LD_PRELOAD.
> In fact, Carlos brought up a great philosophical question:
> "Is linking to libraries through a content-addressable value allowed
> for LGPL software?"
> What if the linked address also forced the content-address by having
> it resolve to something on IPFS ?
Oh you mean it could be thought of a static linking, conceptually?
Good question.
Ludo’.
prev parent reply other threads:[~2022-01-18 14:52 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-03 20:05 Alternative solution to stat storm problem Farid Zakaria
2022-01-08 21:22 ` Ludovic Courtès
2022-01-09 3:00 ` Farid Zakaria
2022-01-09 3:05 ` Farid Zakaria
2022-01-10 18:13 ` Tom Scogland
2022-01-18 14:00 ` Ludovic Courtès
2022-01-18 13:56 ` Ludovic Courtès [this message]
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