Proposal to reduce anti-bundling requirements

[Dave Love]

Michael Stahl <mstahl at redhat.com> writes:

>> Symbol interposition is used a lot for very useful features, blocking
>> interposition would break a lot of stuff.
>
> really?  i've always thought that it was only useful for libc symbols,
> but maybe that's because i don't work on base OS stuff.

I'd guess most uses are not to do with base OS stuff.  It's important in
a lot of cases in research-type computing support, though that doesn't
seem to count for much.

Profiling and other instrumentation in the high performance computing
world (where it's taken quite seriously) typically uses LD_PRELOAD
libraries.  For instance, that's essentially required by useful
implementations of the mechanisms defined by the MPI standard, as
embodied in the openmpi and scorep-openmpi Fedora packages, inter alia.
There are varied other HPC uses, like compensating for filesystem
deficiencies, and I've known (non-Unix) library preloads as an extension
mechanism since the 80s.  [Yes, there's a potential problem with users
trashing the "system" items you'd like in LD_PRELOAD.]