Re: The perennial i386 floating-point rounding issue...

[Jan Hubicka <jh at suse dot cz>]

> On Thursday, 13 June 2002 06:41, Jan Hubicka wrote:
> > > >-march isn't a reliable guide to whether SSE is available, at
> > > > least for AMD chips. According to AMD's docs, everything from the
> > > > Athlon 4 (a.k.a. Thunderbird) on has been made in both SSE and
> > > > no-SSE versions, and the only reliable way to detect SSE is via
> > > > the feature flags from the CPUID instruction.
> > >
> > > Sorry, this just isn't true.  No Thunderbirds (aka Athlon model 4)
> > > were ever made with SSE support.
> >
> > Thats it.  THere is little bug in SPECs making GCC to define __SSE__
> > for tbirds.  I believe it is fixed already, I will double check.
> 
> It's present in the 3.1 release. (That wasn't what I was going by, 
> though; see below.)

Yes,
I hope it is fixed for 3.1.1
There is some dust that needs to settle down around the SSE support,
hope that 3.1.1 will be out soon, so it will hit the main distros.
I will check the current state tonight.
> I was also going by the behaviour of GCC in response to the -mathlon* 
> options. SSE is enabled (internally, I mean, not going by the erroneous 
> __SSE__ preprocessor macro) for -mathlon-4, -mathlon-mp, and 
> -mathlon-xp, but not for -mathlon or -mathlon-tbird. I took that to 
> mean that -mathlon-tbird was intended to mean "Athlon model 4 without 
> SSE", while -mathlon-4 meant "Athlon model 4 with SSE". I didn't know 
> about the Mobile Athlon quote-4-unquote mess; now that I do, I assume 
> this is the chip -mathlon-4 was meant to refer to.
> 
> I think some of those options should be renamed, or at least carefully 
> documented; surely it's natural to assume that -mathlon-4 means Athlon 
> model 4? Most people aren't likely to know about the Mobile Athlon 
> mess. (I'll volunteer to write some documentation for this area if 
> necessary.)

Yes, the situation is extremly messy and any additional documentation is
welcome I guess :)

Honza
> 
> Kelley, where did you get your information from? It took me some effort 
> in cross-checking between the information on AMD's site and third-party 
> sites (notably sandpile.org) to put together a definitive list of AMD 
> chips and what was enabled (according to the docs) on each of them. If 
> there's a more reliable source that I haven't found, I'd like to know 
> about it.
> 
> CPU                aka           MMX       3DNow     SSE
> K5                 --            no        no        no
> K6                 --            yes       no        no
> K6-II              --            yes       yes       no
> K6-III             --            yes       yes       no
> Athlon model 1     K7            extended  extended  no
> Athlon model 2     K75           extended  extended  no
> Duron model 3      Spitfire      extended  extended  no
> Athlon model 4     Thunderbird   extended  extended  optional
> Athlon XP model 6  Palomino      extended  extended  optional
> Duron model 6      Morgan        extended  extended  optional
> Athlon XP model 7  Thoroughbred  extended  extended  optional
> 
> -- 
> Ross Smith ..................................... Auckland, New Zealand
> r-smith@ihug.co.nz ...................................................
> 
>   "Never underestimate the power of stupid things in large numbers."
>                                                       -- Serious Sam