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Re: Supported Hardware ?

On Mon, Oct 24, 2016 at 09:45:29PM +0200, Karoly Balogh (Charlie/SGR) wrote:
> That is indeed the case.
> That's what the sane part of the Amiga world has been asking for a while.
> That's what the sane part of the Amiga world has been telling for a while.
> :)

Oh good, everyone seems to agree then.

> That doesn't apply to Amiga PowerPC software. All Amiga PowerPC systems
> and expansion cards from the very early days had a full standard PPC FPU.
> (We are talking about almost two decades of compatibility in this case.)

Hmm, that does make sense.  OK, this board should just die and go away
then. :)

I only have an over equipped A500, so no ppc amiga for me so far.

> So this board will be an exception in every possible sense, and either
> incompatible with existing software base, or running them with a huge
> penalty hit. Heck, almost all performance-intensive PPC software is full
> with hand-optimized stuff like memcopy with FPU, and so on, to squeeze
> out all bits of performance from the previous low-end boards which were
> the only ones available...
> Yes, the A1222 is running powerpcspe, although some ran the normal powerpc
> kernel as well with math emu, but it's "not recommended", AFAIK.

Certainly it doesn't look like linux distributions for powerpc tend to
ship with MATH_EMULATION enabled in their kernels.  So to claim the board
is compatible with standard linux distributions for powerpc is false.

> For AmigaOS, where most of the software, esp. legacy ones only exist in
> binary distributions, they always make an analogy with the "software
> supported" FPU of the 68040 and 68060 CPUs (in short for those unfamiliar:
> those CPUs never implemented the full 68881 FPU instruction set, mainly
> trigonometry-related instructions were missing, and they were supported by
> a software library provided by Motorola for user space apps), meaning that
> because that was working reasonably well, this should be working fine too
> in the end.
> Obviously anyone with that reasoning doesn't get the depth of the problem
> in this case.

Yes the 68k programs used the libraries because most hardware didn't
have an FPU so the libraries were handy.  It makes sense for PPC code
to expect an FPU.

> I'd say a "performance hit" is quite an understatement, given the existing
> software base. But we'll see. At least not many of their betatesters is
> so willing to post benchmarks, which is always an answer to many
> questions...

I remember the difference between arm and armel and then armhf.
Emulation of hardware sucks when you trap, and using libraries when you
could use hardware directly also sucks (but not as much).

> Yeah, same here.

I wonder if they will sell any.

Len Sorensen

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