Thorsten Froehlich <tho### [at] trfde> wrote:
> 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>

  I think that you both are confusing two things with each other.

  Compilers and software out there (including operating systems) are slowly
migrating to use SSE instead of the FPU, at least in the new 64-bit systems
(which is non-problematic because all amd/intel-based 64-bit systems do
have full SSE support).

  However, that is, for the umpteeth time, not what I'm objecting against.

  What I'm objecting against is the claim that operating systems running
on hardware *with* FPU are going to simply deliberately deny software
working access to the FPU.

  For the umpteeth time, that doesn't make any freaking sense. Is, for
example, the linux project going to say: "Sorry, you can't run the newest
kernel in a Pentium4 because we decided to drop support for programs using
the FPU"?

  It may be that in the future the kernel itself may not use the FPU at
all. That's, however, a completely different thing for it to drop support
for processors with an FPU and all software using it. It would, in fact,
completely go against one of the design principles of linux: To be as
portable as possible. Linux is one of the most portable systems out there
(only netbsd rivals it). Are they going to drop support for 90% of the
hardware out there for no good reason? I don't think so.

  When I ask about any concrete evidence that any operating system out
there is planning to actively deny access to the FPU, all I get is
material which talks about compilers migrating to SSE in 64-bit systems,
which has nothing to do with the issue.

-- 
                                                          - Warp

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Warp wrote:
>   When I ask about any concrete evidence that any operating system out
> there is planning to actively deny access to the FPU, all I get is
> material which talks about compilers migrating to SSE in 64-bit systems,
> which has nothing to do with the issue.

Guess what ABI you need to use to call your operating system functions that 
take floating-point arguments on x86-64? Hmm, you guess right: You put them 
in SSE registers. And you cannot copy directly between SSE and x87 registers 
(you need to go through memory). That is called "deprecated by an operating 
system".

And maybe you ought to look up the word "deprecated" in the dictionary. It 
is *not* a synonym for "deny"...

	Thorsten

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Thorsten Froehlich <tho### [at] trfde> wrote:
> And maybe you ought to look up the word "deprecated" in the dictionary. It 
> is *not* a synonym for "deny"...

  So OS'es are *not* going to drop support for programs using the FPU.
They will still run older software which uses the FPU (at least on platforms
which *have* a FPU). It's just that software written for newer 64-bit
processors should not use it.

  That's all I wanted to agree with.

-- 
                                                          - Warp

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Warp <war### [at] tagpovrayorg> wrote:
> > 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?

The proof is in my argument: The x87 will not live eternally, one way or the
other.

>   (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.)

Even Windows software occasionally sees new versions of itself - or at least so
I heard tell.

> > - 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.

Warp, why don't you get this one of my points, now once and for all: The desire
of chip manufacturers *may* be the reason for OS manufacturers to go into that
direction.

May, can be, possibly. I'm saying nothing more. But that *IS*, for heaven's
sake, a possible reason, and it *HAS*, for heaven's sake, something to do with
it.

If you don't get this, sorry, your problem.

> > - 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.

That statement of yours is BS for reasons I keep trying to explain to you, but
it seems you don't listen - you just dismiss my points with some circular kind
of argument.

> > - 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.

With the Linux kernel - pretty well sure. But with a closed-source OS like
Windows? You just mentioned above that users can't just re-compile
closed-source software.

So the mainstream software would have to do the right thing off-the-shelf.

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

Yah yah yah... heard that long enough from you.


> > 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.

But speedup *OF SSE ITSELF* may have...

.... (geez, you're having me close to shouting out loud "dummo!" right here...)


> > 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.

There's a difference here: Many DOS console software *DOES* run on Vista (at
least I guess so - it does on XP), because Windows has always been *designed*
to still be able to run DOS software. If it doesn't make use of direct hardware
access or 32-bit mode, that is.

Linux has never run DOS executables "natively". There may be add-ons to do so,
which may even be included in typical distributions, but they're not part of
the OS as such.


> (Well, DOS is *not* an operating system at all.)

Then what do you think it's named for? "Disk Ohjesushelpme System"?

Your definition of an operating system may be somewhat biased by the times of
scheduled multitasking and multicore systems.


Now, 'nuff said. If you are not willing to get my points, then forget about it.

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Warp <war### [at] tagpovrayorg> wrote:
>   For the umpteeth time, that doesn't make any freaking sense.

And for the umpteeth time, we just plainly disagree with the categorical "not
any" part of the statement of yours, because we do see some *possible* sense in
it.

>   When I ask about any concrete evidence that any operating system out
> there is planning to actively deny access to the FPU, all I get is
> material which talks about compilers migrating to SSE in 64-bit systems,
> which has nothing to do with the issue.

.... and some statement from AMD that, for some reason, hints that some OS or the
other *may* actually go that path.

It's out there to read, and may *or* may not be based on sound plans by some
vendors. But it's there.

So when you keep crying out "why, it can't make any sense", I'd say there may be
some after all.

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clipka <nomail@nomail> wrote:
> Warp <war### [at] tagpovrayorg> wrote:
> > > 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?

> The proof is in my argument: The x87 will not live eternally, one way or the
> other.

  In other words, you made a claim with no proof.

  Well, my claim is that eg. linux will never drop support for the FPU when
compiled for a platform with a FPU. Please prove me wrong.

  Linux will never drop the support because that would blatantly go
against the very principles of Linux: To be a highly portable OS which
can be run on very various platforms. Some part of the Linux community
even has some kind of unofficial "competition" with NetBSD to see who
supports more platforms.

> >   (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.)

> Even Windows software occasionally sees new versions of itself - or at least so
> I heard tell.

  I don't think you understood what I wrote above.

> > (Well, DOS is *not* an operating system at all.)

> Then what do you think it's named for? "Disk Ohjesushelpme System"?

  I knew you would argue that, because that's what everyone argues.

  If I make a program which prints "hello world" and name the program
HWOS, standing for "hello world operating system", does that make my
program an operating system?

  Please answer "yes" or "no".

> Your definition of an operating system may be somewhat biased by the times of
> scheduled multitasking and multicore systems.

  It's not *my* definition.

> Now, 'nuff said. If you are not willing to get my points, then forget about it.

  I will be willing to get your points when you show me some actual concrete
*proof*. For example, I would be *really* interested in seeing some proof
about the linux community planning to completely drop support for programs
using the FPU.

  Some obscure statement in some AMD technical manual with a passing note
on OS FPU support is not proof of anything.

-- 
                                                          - Warp

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Warp <war### [at] tagpovrayorg> wrote:
> Thorsten Froehlich <tho### [at] trfde> wrote:
> > And maybe you ought to look up the word "deprecated" in the dictionary. It
> > is *not* a synonym for "deny"...
>
>   So OS'es are *not* going to drop support for programs using the FPU.
> They will still run older software which uses the FPU (at least on platforms
> which *have* a FPU). It's just that software written for newer 64-bit
> processors should not use it.
>
>   That's all I wanted to agree with.

And since 64-bit is the natural evolution, it'd also mean eventually no software
will use the FPU anymore...

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nemesis <nam### [at] gmailcom> wrote:
> And since 64-bit is the natural evolution, it'd also mean eventually no software
> will use the FPU anymore...

  Given that all current 64-bit processors have a perfectly good FPU,
I don't see that coming anytime soon either...

  (It's one thing what Intel and AMD would like things to go, and another
thing what the market says.)

-- 
                                                          - Warp

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Warp wrote:
>   For the umpteeth time, that doesn't make any freaking sense. Is, for
> example, the linux project going to say: "Sorry, you can't run the newest
> kernel in a Pentium4 because we decided to drop support for programs using
> the FPU"?

For the umpteeth  time, go to off-topic.

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Warp wrote:
>   It's not *my* definition.

 From WikiPedia:

"""
An operating system (commonly abbreviated OS and O/S) is the infrastructure 
software component of a computer system; it is responsible for the 
management and coordination of activities and the sharing of the limited 
resources of the computer. The operating system acts as a host for 
applications that are run on the machine. As a host, one of the purposes of 
an operating system is to handle the details of the operation of the 
hardware. This relieves application programs from having to manage these 
details and makes it easier to write applications.
"""

Sure sounds like MS-DOS to me. And CP/M, and TRS-DOS, for that matter. 
Unless you don't count memory, serial and parallel ports, keyboard, disk 
space, and network connections as "limited resources".

Follow-ups yet again redirected.
-- 
   Darren New, San Diego CA, USA (PST)
   The NFL should go international. I'd pay to
   see the Detroit Lions vs the Roman Catholics.

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