clipka <nomail@nomail> wrote:
> > People simply won't buy a computer
> > which cannot run their software. It's that simple.

> :)

> They keep buying new OS versions which cannot run their software (they even run
> for leaked pre-beta versions), so why should they be any more picky with their
> hardware :)

  Even Windows Vista can run Windows 1.0 software (with some tweaking).
Just google for it.

  Sure, *some* software has stopped working with new versions of Windows,
but a rather small amount of them.

  What you are talking is completely different. It's a total cut from
software older than a certain age.

-- 
                                                          - Warp

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clipka <nomail@nomail> wrote:
> And you can compile a Linux kernel that doesn't
> include support for them either.

  I can compile a Linux kernel that doesn't run at all. What does that prove?

> > The OS plays no role in this process.

> It does. As long as it invokes x87 FPU commands in an attempt to store their
> contents for a task switch, you can't strip those commands from your CPU,
> because it would break the OS.

  And as long as the OS is run on a system with FPU and with programs using
the FPU, the OS cannot drop support. It's that simple.

  As I have said like a dozen times, it makes absolutely no sense for an OS
to drop support for the FPU if the computer has one.

  The OS does *not* play any role in the migration from FPU to SSE.

> > > We're not talking abount months here. We're talking about years. Lots of.
> >
> >   And exactly how does the OS drop support for the FPU gradually, during
> > the years?

> Don't ask me.

  I'm asking you because you said it.

> Ask Microsoft, Apple, the Linux community, and Intel and AMD.

  They are not dropping support for the FPU in their OS, so why should
I ask them? Why are they not dropping it? I have repeated it a dozen of
times already: It doesn't make any freaking sense. If the hardware has
an FPU, the OS supports the FPU, period.

  You can't "migrate" the OS to "not support the FPU" over several years.
It either supports it or doesn't. There's no middle ground.

> I'd say: Deprecate x87 FPU use; encourage compiler vendors to default to not
> using it; introduce new OS API calls that do no longer use x87 FPU registers
> for parameter passing (if applicable); deprecate the old API calls; deprecate
> x87 FPU use, deprecate it again and again

  Which is completely different from the OS refusing to run software which
uses the FPU.

> - and then ultimately release a new
> version that just doesn't support it anymore.

  Which would be absolutely nonsensical in a computer with a FPU.

  What are they going to do? Pop up an error dialog saying "sorry, although
this computer does have a FPU, I'm not going to allow you to use it, tough
luck"? Haha.

  How many times do I have to repeat myself? It doesn't make any sense.

> By that time - to mention it again - the percentage of software actually using
> the x87 FPU will have diminished. That is the "gradual" part of this phasing
> out.

  Even if there's 0 new software which uses the FPU, if the OS is run on
a computer with an FPU, it makes absolutely no sense not supporting it and
actively boycotting any software which tries to use it.

-- 
                                                          - Warp

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On Fri, 02 Jan 2009 10:46:51 -0800, Darren New <dne### [at] sanrrcom> wrote:

>nemesis wrote:
>> Why is there not a povray.flamewars newsgroup? :)
>
>I vote for povray.flamewar.redirect.redirect.redirect

RTFM My son :-)

BTW Not aimed at you ;)
-- 

Regards
     Stephen

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Warp wrote:
> clipka <nomail@nomail> wrote:
>> But maybe what you mean is trigonometric functions. These, indeed, may be
>> not so commonplace.
> 
>   Thunderbird seemed to at least use logarithms...

Wow, any idea what for?

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Warp <war### [at] tagpovrayorg> wrote:
>   What you are talking is completely different. It's a total cut from
> software older than a certain age.

No, because software older than a certain age is 32-bit software.

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Warp <war### [at] tagpovrayorg> wrote:
>   How many times do I have to repeat myself? It doesn't make any sense.

How long do I have to repeat myself: They're gonna do it some day.

Maybe that'll be the day when they introduce a whole new generation of CPUs
which is no longer compatible to x86 at all, but the day will come.

And they're pondering the idea (or at least have pondered it some time like
beginning of 2008) of dropping the x87 FPU support earlier. I have no idea why
(except wild guesses), but it must have went through their heads.

So all I'm saying here is: Make your software ready for it if it doesn't really
need the FPU. And if AMD is right in that it's not a loss but actually even a
gain, then all the more reason to do so.

That's the bottom line of it. No more, and no less.

All I can give you regarding the "why" is some wild guesses, and they *do* make
*some* sense. It's not *total* bullshit.

>   Even if there's 0 new software which uses the FPU, if the OS is run on
> a computer with an FPU, it makes absolutely no sense not supporting it and
> actively boycotting any software which tries to use it.

I repeat, it *does* make *some* sense (I'm not saying it makes *enough* sense):

- There *may* be reasons for chip manufacturers to want to get rid of the x87
FPU in their CPU design. It's complex, and may be in the way for optimizations
of other components. So holding on to the FPU may actually be a performace
problem for *all* software that *does* fine without it or at least *could*
(which I bet is the vast majority).

- You can't strip the x87 FPU off the CPU unless the OS are ready for it, for
about the same reason that you (to some degree undoubtly righteously) argue
that you can't just strip FPU support off the OS.

- The OS *may* not be ready for it unless it itself has totally dropped the x87
FPU support (e.g. due to FPU commands that it may have to issue during task
switching, which may cause a mess on a CPU that doesn't support the x87 FPU)

So we *may* be talking about a way to achieve some significant additional
speedup for 99% of the software that will be out there in, say, 5 years.

If that is the case, I would see that as enough reason to break a few other
pieces of software.


BTW, your claim that you can get every old stuff to run on Vista is BS. Think
for example about the numerous DOS games, which are being "actively boycotted"
and denied direct access to hardware when run under modern OS. And other
software suffered the same issues. Why? Because there was a benefit to be
gained - in that case in terms of stability. Would you say that was a wrong
move?

I'm glad Windows is as stable as it is. (Which is not to say that I praise it
for exceptional stability, but stability back then was far worse.)

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clipka wrote:
>> Actually, it is not more complex than integer addition and multiplication.
<snip>
> - Normalize the smaller number to match the larger one's exponent
<snip>

This is a simple shifting operation. The other operations you mentioned are 
bit-tests and other simple logic on a few bits.

	Thorsten

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Thorsten Froehlich <tho### [at] trfde> wrote:
> >> Actually, it is not more complex than integer addition and multiplication.
> <snip>
> > - Normalize the smaller number to match the larger one's exponent
> <snip>
>
> This is a simple shifting operation. The other operations you mentioned are
> bit-tests and other simple logic on a few bits.

And yet it doesnt change the fact that it *IS* more complex than integer
addition: It is not just an elementary operation, but a combination of multiple
such ops.

Well, maybe not much more complex than the int multiplication, but that wasn't
my initial point anyway. I'd call integer multiplication non-trivial in that
sense as well.

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clipka <nomail@nomail> wrote:
> Warp <war### [at] tagpovrayorg> wrote:
> >   How many times do I have to repeat myself? It doesn't make any sense.

> How long do I have to repeat myself: They're gonna do it some day.

  Can you give me a reference to, for example, an online linux community
where they are discussing this?

  Or are you, too, making a claim with absolutely no proof?

  (In fact, with linux it even *might* be plausible because 99.9% of the
software for it is open source and it's more or less trivial for every
distro to just recompile *everything* for the new system. With Windows,
which is plagued with old, closed source software, I don't think so.)

> Maybe that'll be the day when they introduce a whole new generation of CPUs
> which is no longer compatible to x86 at all, but the day will come.

  Did I say something different? No.

  What I said that making an OS which works on a PC with an FPU so that it
deliberately stops programs from using the FPU makes absolutely no sense.

> - There *may* be reasons for chip manufacturers to want to get rid of the x87
> FPU in their CPU design.

  Which has nothing to do with the OS dropping support even in CPUs with
a FPU.

> - You can't strip the x87 FPU off the CPU unless the OS are ready for it, for
> about the same reason that you (to some degree undoubtly righteously) argue
> that you can't just strip FPU support off the OS.

  And the OS cannot drop support because 99% of software uses it. So they
are rather locked.

> - The OS *may* not be ready for it unless it itself has totally dropped the x87
> FPU support (e.g. due to FPU commands that it may have to issue during task
> switching, which may cause a mess on a CPU that doesn't support the x87 FPU)

  I'm pretty sure it's very easy for them to compile a special version of
the OS for a platform with no FPU. I would be surprised if you couldn't do
that eg. with the Linux kernel.

  It's not a question of difficulty. It's a question of allowing software
to run.

> So we *may* be talking about a way to achieve some significant additional
> speedup for 99% of the software that will be out there in, say, 5 years.

  Software speeding up by using SSE has nothing to do with whether the OS
supports the FPU or not.

> BTW, your claim that you can get every old stuff to run on Vista is BS. Think
> for example about the numerous DOS games, which are being "actively boycotted"
> and denied direct access to hardware when run under modern OS.

  Vista doesn't boycott old DOS software any more than eg. Linux does.
They are basically completely different operating systems. (Well, DOS is
*not* an operating system at all.)

-- 
                                                          - Warp

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Warp wrote:
> clipka <nomail@nomail> wrote:
>> Warp <war### [at] tagpovrayorg> wrote:
>>>   How many times do I have to repeat myself? It doesn't make any sense.
> 
>> How long do I have to repeat myself: They're gonna do it some day.
> 
>   Can you give me a reference to, for example, an online linux community
> where they are discussing this?

Maybe they are not as argumentative as you about things they cannot change? :-P

As I said before, the x86-64 ABI requires passing of floating-point 
arguments in SSE registers on Windows, Linux and Mac OS X. You are free to 
Google for gcc's implementation of the x86-64 ABI, which does exactly that. 
Maybe try <http://www.google.com/search?q=site%3Agcc.gnu.org+x87+deprecated>

And no, I don't want to get into an argument over what search results this 
query returns!!!

	Thorsten

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