[TUHS] Re: mental architecture models, Anyone ever heard of teaching a case study of Initial Unix?

[Warner Losh <imp@bsdimp.com>]

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On Mon, Jul 8, 2024 at 8:41 PM Dave Horsfall <dave@horsfall.org> wrote:

> On Mon, 8 Jul 2024, Adam Thornton wrote:
>
> > Indeed, S/390 Linux ran just fine on machines without IEEE floating
> > point.  Which meant that for years I had to jam `use integer` at the top
> > of any Perl I ran, because otherwise any Perl arithmetic at all would go
> > through the software float routines, which was very painful on little
> > machines, such as a P/390.
>
> When it comes down to it, why would a kernel need floating point?  Or are
> you talking about the distribution instead of the OS?
>

Not floating point, per se, but there's things like AESNI that use special
registers
that are akin to floating point (I can't recall if they are shared with the
FP registers
or not off the top of my head). For doing crypto fast, these are often
used. The same
the same facilities that FP uses to save/restore them on context switches.

Warner

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