[lsb-discuss] Using SSE2 instructions in 32-bit x86 LSB code?

Wichmann, Mats D mats.d.wichmann at intel.com
Thu Oct 22 08:08:41 PDT 2009


Dallman, John wrote:
> I'm responsible for LSB compliance for the Parasolid family of
> 3D CAD/CAM libraries, which are closed-source binary-distribution
> commercial software. I'm working on updating our builds to GCC 4.3
> on SLES11.
> 
> I'm contemplating compiling for SSE2 in the 32-bit x86 build, for
> better floating-point performance. Is this legitimate under the
> LSB standards? SSE2 is standard for x86-64, of course, but the
> 32-bit LSB packages are built for the 486 instruction set, causing
> me to wonder if the standard mandates that.

the ia32 instruction set story is way too restrictive at the
moment, it was written alsmost a decade ago when the "lowest common
denominator" was... well, a decade ago :)

what we really want is that a program you supply will not just plain
fail in ugly fashion when run on a conforming system.  it would do
that if it had unsupported instructions - if you have no fallback
mechanism.  if you can somehow detect an older processor and fall
back to something slower, that is abslutely fine.  in my opinion,
you don't have to support every piece of hardware that could
theoretically run an LSB compliant operating system, you can
restrict that and say only certain things are okay - just because
the spec says something is supported doesn't mean your own business
decision has to be to support it: and in this case, you could
refuse to install, or refuse to sell, or however you want to
restrict it.  I don't think LF would deny you usage of the LSB
mark if this were your approach, it that's something you're looking at.


> I'm afraid I can't locate the standards documents on the website to
> find out for myself; I can't make any sense of this version of the
> site.

sorry, I have to agree with you on that.  published standards are always
available under refspecs.linuxfoundation.org no matter what else
happens.


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