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

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

On Sun, 26 Mar 2023 at 18:15, Michael van Elst <mlelstv%serpens.de@localhost> wrote:
>
> abs%netbsd.org@localhost (David Brownlee) writes:
>
> >That would be the ideal "default" case - though would that most likely
> >involve loading the kernel first into the largest segment,
>
> There is no "default" case. Often you have a mixed zoo of memory regions
> and the largest region isn't necessarily the best choice for the kernel.
>
> Using the region with the highest priority (usually the fastet, not the
> largest) can be a good default. Unless you think that your application
> code can use that memory better than the kernel.
>
> Also, with todays kernel sizes, there is often no choice.

Hence this discussion on adjusting default behaviour :)

A default of "pick the highest priority region which into which the
kernel would fit" should do the optimal option of putting the kernel
into the fastest memory where possible, falling back to slower memory
where not possible, while (crucially) not failing to boot if any
higher priority regions are too small.

If implementing "kernel would fit" would be too complex, then an
alternative of "pick the highest priority region which is at least 8
MB" (and allowing both the 8 to be adjusted, and for the behaviour to
be overridden to pick the largest) should allow optimal option in
*almost all* cases, with a very low risk of failing to boot if someone
builds an unusual kernel.

Thanks

DAvid