Re: loadbsd memory segment (Was: NetBSD Amiga - Memory restrictions)

[David Brownlee <abs%netbsd.org@localhost>]

On Sat, 25 Mar 2023 at 17:44, Karoly Balogh <charlie%scenergy.dfmk.hu@localhost> wrote:
>
> Hi,
>
> On Sat, 25 Mar 2023, Frank Wille wrote:
>
> > >> > An other thing is loadbsd, is it possible to load the Kernel in the
> > >> > TK-Memory 0$800000 instaed of the biggest available block, which
> > >> >  could e slow Z3 RAM?
> > >>
> > >> Option -p should work, which selects the memory segment with the
> > >> highest priority instead of largest size.
> > >
> > > Maybe the default heuristics could be adjusted - load the kernel into
> > > the highest priority memory segment of at least X MB (and make X an
> > > optional command line option).
> >
> > Agreed. Selecting the memory segment by priority is mostly the better
> > option.
> >
> > But other NetBSD developers already must have had these throughts decades
> > ago, so I'm always afraid we are missing something... ;)
>
> Maybe, but decades ago the Amiga hardware landscape looked very different.
> The 128MB (or 256MB memory) memory that was theoretically available as
> "localfast" seemed huge, and was almost always the largest block. It's
> still true for most A1200 installations of course. But meanwhile 112MB
> mods for the big-box mainboards became a thing, huge ZIII expansions
> became a thing, etc.
>
> I think the kernel should be always loaded to the CPU card local fast ram,
> if possible, for performance reasons, which works just fine with the
> memory-priority system, as that chunk is always the highest prio.

That would be ideal in almost every case - but the edge case of a
machine with a small amount of fast RAM and a larger amount of slower
memory would then fail. Having a 'minimum amount of RAM' value,
adjustable by a param,  combined with defaulting to -p should make the
default work in ~every case, and be optimal in almost all

Continuing my self appointed role as "loud voice that encourages
others to do the actual work" - is anyone interested? :)

David