Re: arch optimation for debian packages (here: soundtouch)
On Mon, 2015-01-26 at 22:54 +0500, Andrey Rahmatullin wrote:
> On Mon, Jan 26, 2015 at 01:14:39PM +0100, Nico Schlömer wrote:
> You cannot unconditionally use instructions not supported by minimal CPUs
> in each architecture, this means no MMX in i386 and only SSE2 and earlier
> on amd64. You can enable anything at run time if support was detected.
The are exceptions, for example tbb (the Intel threading building blocks
library) is available on i386, but it actually requires a Pentium 4
[1].
That said, IIRC some packages had special builds enabling certain
optimizations, i.e. a package would expose a virtual libX that is
provided by special builds libX-default, libX-sse, libX-sse2, and ...
that all conflict and replace each other. I'm not sure if there are
still libraries packaged like this in the archive though.
Something like this would probably be easier to create from the
packagers point of view than patching the upstream code to do run-time
detection.
There was also some discussion about this topic some time ago that
considered providing all these libraries in one package, but installed
in the proper places and then ld-linux.so.2+ldconfig apparently load the
right library [2].
best
Gert
[1] https://www.threadingbuildingblocks.org/system-requirements
[2] https://lists.debian.org/debian-mentors/2000/11/msg00238.html
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