Re: Installing a wrapper guile script in <out>/bin

[Ludovic Courtès]

Hi!

elaexuotee@wilsonb.com skribis:

> More specifically, the package I have builds separate libraries for CPUs with
> AVX, AVX2, and no AVX support. Since build-type isn't sufficiently specific to
> distinguish such CPU features, I have, so far, opted to just build all three
> libs and stuff them under <out>/lib/<foo>.
>
> My idea is to have the linker script check CPU features at runtime (by parsing
> /proc/cpuinfo or something) and executing the binary with the parameters to
> load the correct binary.
>
> Perhaps there is a better overall approach?

I wrote about this topic in the past:

  https://hpc.guix.info/blog/2018/01/pre-built-binaries-vs-performance/

I you’re the upstream author, I recommend using one of the techniques
given above to provide so-called “fat binaries” that contain several
implementations of the performance-sensitive functions; the loader
will pick the right implementation when the program starts.

If you’re downstream… it depends on the specifics.  The loader is also
able to pick a .so from the right lib/ sub-directory depending on the
micro-architecture.  You can try:

  LD_DEBUG=files your program

to see where the loader looks for shared libraries.

HTH!

Ludo’.