On Sun, Oct 20, 2013 at 10:04 AM, Ingo Jürgensmann
<i...@2013.bluespice.org> wrote:
> Am 20.10.2013 um 01:46 schrieb Thorsten Glaser <t...@mirbsd.de>:
>> Geert Uytterhoeven dixit:
>>> FPU emulation should be fine, AFAIK (never used it myself, though).
>> Michael Schmitz dixit:
>>> The docs are quite clearly out of date. From memory, there may be the odd
>>> FPU
>> […]
>>> Seeing as this code is crucial, I'd opt for putting it back in, and finding
>> These two statements are “it should be fine but I don’t really know”
>> and “this is important so put it back in, but I don’t remember details”.
>> Together with what *is* currently in the documentation, this is
>> *not* reassuring, and I *know* that FPU emulation code all across
>> OSes (kernels and not) is a sore topic (even being kicked from
>> some of them).
>> My request for a clear statement still stands.
>
> ... and there's the statement from Adrian that it works without problems so
> far.
Indeed. The emulation may be incomplete, but for most people it's useable,
and definitely better than nothing.
Furthermore, for people running Debian on their FPU-less machines before,
the new kernel image is definitely a regression, so it warrants re-enabling
FPU emulation to fix this.
>> On the other hand, I cannot help but wonder how well it compares
>> to whatever ARAnyM passes as FPU. I know ARAnyM doesn’t handle the
>> 80/64bit precision switch at all (which is why we opted to not use
>> that for Python), but I smell some sort of knob here… if the knob
>> can be used to tweak between speed and correctness, I’d opt for
>> correctness. (OK, BSD user speaking.) It’d probably be faster at
>> runtime to fix ARAnyM instead but that’s a different upstream.
>
> Hmmm... if Aranym is the problematic part in this story, then Aranym should
> be changed to reflect how real hardware works. There were a lot of Amiga
> accelerator cards built & sold without an FPU, although most of them have a
> socket for a 68881/2. It's been a matter of money back then and FPUs weren't
> widely used under AmigaOS. Except when you were doing 3D graphics and such.
> But then again one had no A1200 for this purpose but a A2/3/4000 with 68040
> or 68060s. But the majority of sold accelerator cards, I believe, was for
> A1200 and 68030 just for the reason of money.
>
> At least I opt for providing a FPU enabled kernel. It doesn't need to be the
> default kernel, but we shouldn't exclude a number of users just because an
> emulator might have problems with FPU emulation. It's easier to change that
> piece of software than to change the piece of hardware.
Nevertheless, FPU emulation in ARAnyM is something different. ARAnyM
is an emulator that emulates a full 68040, incl. FPU. So as far as the Linux
kernel is concerned, no in-kernel FPU emulation is involved.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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