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From: Michael S <already5chosen@yahoo.com>
Newsgroups: comp.arch
Subject: Re: 80286 protected mode
Date: Sun, 13 Oct 2024 10:56:20 +0300
Organization: A noiseless patient Spider
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On Sat, 12 Oct 2024 18:32:48 +0000
mitchalsup@aol.com (MitchAlsup1) wrote:

> On Sat, 12 Oct 2024 5:06:05 +0000, Brett wrote:
> 
> > MitchAlsup1 <mitchalsup@aol.com> wrote:  
> >> On Fri, 11 Oct 2024 12:10:13 +0000, David Brown wrote:
> >>  
> >>>
> >>> Do you think you can just write this :
> >>>
> >>> void * memmove(void * s1, const void  * s2, size_t n)
> >>> {
> >>> return memmove(s1, s2, n);
> >>> }
> >>>
> >>> in your library's source?  
> >>
> >>       .global memmove
> >> memmove:
> >>       MM     R2,R1,R3
> >>       RET
> >>
> >> sure !
> >>  
> >
> > Can R3 be a const, that causes issues for restartability, but branch
> > prediction is easier and the code is shorter.  
> 
> The 3rd Operand can, indeed, be a constant.
> That causes no restartability problem when you have a place to
> store the current count==index, so that when control returns
> and you re-execute MM, it sees that x amount has already been
> done, and C-X is left.

I don't understand this paragraph.
Does constant as a 3rd operand cause restartability problem?
Or does it not?
If it does not, then how? 
Do you have a private field in thread state? Saved on stack by by
interrupt uCode ? 
OS people would not like it. They prefer to have full control even when
they don't use it 99.999% of the time.