osmo-trx[master]: ssedetect: Add runtime CPU detection

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dexter gerrit-no-reply at lists.osmocom.org
Fri Apr 28 10:16:18 UTC 2017


Patch Set 3:

Hello Alexander,

I have some questions about this. You suggested to add some fake-target for avx.
Maybe I get the things wrong, but I think the things will be not just some
changes in the build system.

Currently the targets are compiled with -msse4.1 and -mavx. The targets are
both different and result into two different .a files. The function prototypes
have also different names to avoid clashing. Then the runtime CPU detection
detects which CPU is installed and picks the matching implementation by
populating some generically named function pointers. Thats how we switch
between the different implementations dynamically.

You said the avx is similar to (when I remeber correctly) sse 4.1. So technically
the that code should compile with -mavx as well. But I still need the sse 4.1
support. An avx compiled sse code would not run on a pure sse machine, right?

I would than have to mangle the function prototypes to avoid clashing
between the sse 4.1 and the avx version. And of course we need an additional
check to populate the function pointers.

Maybe I am thinking this overcomplicated, please let me know if I am wrong or
right.

regards,
Philipp

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Gerrit-MessageType: comment
Gerrit-Change-Id: Iba74f8a6e4e921ff31e4bd9f0c7c881fe547423a
Gerrit-PatchSet: 3
Gerrit-Project: osmo-trx
Gerrit-Branch: master
Gerrit-Owner: dexter <pmaier at sysmocom.de>
Gerrit-Reviewer: Alexander Chemeris <Alexander.Chemeris at gmail.com>
Gerrit-Reviewer: Harald Welte <laforge at gnumonks.org>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: Max <msuraev at sysmocom.de>
Gerrit-Reviewer: Vadim Yanitskiy <axilirator at gmail.com>
Gerrit-Reviewer: dexter <pmaier at sysmocom.de>
Gerrit-HasComments: No



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