Re: Kernel config for Sun 3/50

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

On Wed, 18 Jan 2023 at 19:02, Trent McNair <tmcnair%gmail.com@localhost> wrote:
>
> Thanks!
>
> 1.1m is as small as I've been able to go. This is smaller than my
> SunOS kernel which made me curious.

There may also be a chunk of bss which is not expressed in the
filesize ("size netbsd" may help)

> Sun-3 Architecture manual
> (http://www.bitsavers.org/pdf/sun/sun3/Sun-3_Architecture_Manual_Ver_1.0_Jan85.pdf)
> states:
>
>         Main memory shadowes video, memory in the range of physical addresses
>         starting at 1 megabytes and extending for 128 kilobytes. This
> area of main memory
>         is called the copy region. If the copy enable bit in the
> system enable register is
>         set then data written into this copy region is also written
> into the video memory at
>         the same location within the 128K region. A read from the copy
> region returns the
>         data in main memory and does not affect the video memory
>
> This would seem to indicate that if I'm not using the framebuffer
> (which I am not) I could comment out the Sun 3/50 size check. I'll
> give it a try over the weekend.

Now _that_ is interesting. If it works then that check should
definitely be conditional on the framebuffer being enabled.

Mmm, I wonder if it's possible to have a kernel with bwtwo to have a
fixed 128K of zero data at exactly the right region to overlap with
the framebuffer. Presumably not too hard if that is already in the
data/bss area...

Looking forward to the next update! :)

David