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From: Michael S <already5chosen@yahoo.com>
Newsgroups: comp.arch
Subject: Re: rep movsb vs. simpler instructions for memcpy/memmove
Date: Thu, 13 Mar 2025 16:29:54 +0200
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On Thu, 13 Mar 2025 02:34:11 -0000 (UTC)
Lawrence D'Oliveiro <ldo@nz.invalid> wrote:

> On Thu, 13 Mar 2025 00:49:47 +0000, MitchAlsup1 wrote:
>=20
> > On Thu, 13 Mar 2025 0:03:51 +0000, Lawrence D'Oliveiro wrote:
> >  =20
> >> On Wed, 12 Mar 2025 17:44:11 +0000, MitchAlsup1 wrote:
> >> =20
> >>> My 66000 has MM memmove as an instruction (4-bytes) always
> >>> optimal, no checking required. =20
> >>
> >> Presumably interruptible and resumable ... =20
> >=20
> > Yep; but also include able to take exceptions. =20
>=20
> So you have a VAX-style =E2=80=9Cfirst part done=E2=80=9D processor statu=
s bit? And
> you use architectural registers to save/restore the state of an
> instruction in progress at the time of an interrupt?

According to my understanding, no and no.
Mitch has instruction that saves architectural+microarchitectural
context in memory and any interrupt or exception has to use it.
Architectural part of saved buffer is documented. Microarchitectural
part, apart from its size, not so much.
That is, according to my understanding. Take it with amount of salt you
find appropriate.