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SubjectRe: [RFC PULL] remove arch/h8300
On Fri, 8 Apr 2022, Rob Landley wrote:

> On 4/5/22 08:07, Greg Ungerer wrote:
> > On 5/4/22 13:23, Daniel Palmer wrote:
> >> On Mon, 4 Apr 2022 at 22:42, Greg Ungerer <gerg@linux-m68k.org> wrote:
> >>> But we could consider the Dragonball support for removal. I keep it
> >>> compiling, but I don't use it and can't test that it actually works.
> >>> Not sure that it has been used for a very long time now. And I
> >>> didn't even realize but its serial driver (68328serial.c) was
> >>> removed in 2015. No one seems too have noticed and complained.
> >>
> >> I noticed this and I am working on fixing it up for a new Dragonball
> >> homebrew machine. I'm trying to add a 68000 machine to QEMU to make
> >> the development easier because I'm currently waiting an hour or more
> >> for a kernel to load over serial. It might be a few months.
>
> I've been booting Linux on qemu-system-m68k -M q800 for a couple years
> now? (The CROSS=m68k target of mkroot in toybox?)
>
> # cat /proc/cpuinfo
> CPU: 68040
> MMU: 68040
> FPU: 68040
> Clocking: 1261.9MHz
> BogoMips: 841.31
> Calibration: 4206592 loops
>
> It certainly THINKS it's got m68000...
>

Most 68040 processor variants have a built-in MMU and the m68k "nommu"
Linux port doesn't support them. The nommu port covers processors like
68000, Dragonball etc. whereas the m68k "mmu" port covers 680x0 where x is
one of 2,3,4,6 with MMU.

> $ qemu-system-m68k -cpu ?
> cfv4e
> m5206
> m5208
> m68000
> m68010
> m68020
> m68030
> m68040
> m68060
> any
>
> (I'd love to get an m68k nommu system working but never sat down and
> worked out a kernel .config qemu agreed to run, plus compiler and libc.
> Musl added m68k support but I dunno if that includes coldfire?)
>

I could never figure out how to boot a coldfire machine in qemu either.
There was no documentation about that back when I attempted it but maybe
things have improved since.

> >> It looked like 68328serial.c was removed because someone tried to
> >> clean it up and it was decided that no one was using it and it was
> >> best to delete it. My plan was to at some point send a series to fix
> >> up the issues with the Dragonball support, revert removing the serial
> >> driver and adding the patch that cleaned it up.
> >
> > Nice. I will leave all the 68000/68328 code alone for now then.
>
> The q800 config uses CONFIG_SERIAL_PMACZILOG. Seems to work fine?
>

That driver would work on certain 68000 systems e.g. early Macs. (And IIRC
someone did once boot a customized Linux kernel on a Mac SE...)

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