Re: Linux 6.4.4 on m68k - Q40 - pata_falcon causes oops at boot time

Michael Schmitz
2023-08-15T22:39:29Z

Hi Will,

On 16/08/23 10:10, William R Sowerbutts wrote:
>> As Geert explained, it was agreed by the IDE maintainers that any data byte
>> order fixup needed would be handled in the block layer, and existing byte
>> swapping options were removed as a result (as far as I recall, that was only
>> ever necessary for Falcon and Q40).
> Sensible
>
>>> I'm not clear if pata_falcon on Atari records data on disk in normal or
>>> swapped byte order. Can I take a drive from my Atari Falcon Linux machine
>>> and connect it to a PC without needing to byte swap it?
>> No, such a disk can only be read on a PC when running ARAnyM (where the m68k
>> Linux kernel then handles the necessary fixup). Data are in the wrong byte
>> order when hooking up a Falcon IDE disk to a PC.
> Interesting -- thank you
>
>> 'compatible byte order' would have to be the byte order used by the native
>> OS here. Meaning we pretty much do nothing, just use my latest RFC patch.

I've sent a v3 of my patch which adds a module option to select which
drive will get extra byte swapping on data transfers. Please give that a
try. So far tested on ARAnyM with one Atari and one Mac disk image (the
latter of which would have needed byte swapping by ARAnyM before, and
can now be read without that trick).

If that works, I'd send this patch to linux-ide for review (split in two
parts, the first as the minimal bugfix to restore Q40 support, the
second as optional data portability feature on top).

Cheers,

Michael

> I agree
>
> Will
>
> _________________________________________________________________________
> William R Sowerbutts will@sowerbutts.com
> "Carpe post meridiem" http://sowerbutts.com
> main(){char*s=">#=0> ^#X@#@^7=",c=0,m;for(;c<15;c++)for
> (m=-1;m<7;putchar(m++/6&c%3/2?10:s[c]-31&1<<m?42:32));}
>