Linux and amiga floppy images

Linux and amiga floppy images

[Kolbjørn Barmen]

Hello!

I had a strange observation a few weeks ago that I intended to check with
you guys, but then forgot all about. :P

I was restoring some old amiga systems, and in that process needed to get
software onto floppies. I have a catweasel and can write out so called ADF
files (amiga floppy images) to floppies just fine with it (excellent
hardware). The problem I had was creating ADFs on linux, I assumes I could
just loopback-mount them with affs and just write files to them, but no -
I always ended up getting I/O-error, and the kernel put the filesystem
write-protected.

Deleting files seems to work ok, but once you try to write  a file, the
filesystem chokes, becomes write-protected and the resulting file is a
0-byte entry.

But I didnt give up there, I tried on different systems... much to my
amusement it worked fine on my linux/m68k systems - amigas, macs and
aranym alike!  OK, I thought, maybe endianness, so I tried on my ppc ibook
running linux - same failures as on the PCs. So - something is done very
correct on m68k in regard to affs, that isnt done correct on other archs.
Anyone know what that might be?

(All systems I tried with were running 2.6.2x, ubuntu, debian, gentoo)

Cheers!

-- kolla

Re: Linux and amiga floppy images

[Andreas Schwab]

Kolbjørn Barmen <linux-m68k@kolla.no> writes:

> But I didnt give up there, I tried on different systems... much to my
> amusement it worked fine on my linux/m68k systems - amigas, macs and
> aranym alike!  OK, I thought, maybe endianness, so I tried on my ppc ibook
> running linux - same failures as on the PCs. So - something is done very
> correct on m68k in regard to affs, that isnt done correct on other archs.
> Anyone know what that might be?

If it's not the endianess then the other possible failure mode is
alignment: on m68k all types are at most aligned at a 2 byte boundary.
The structures in <linux/amigaffs.h> don't have any obvious alignment
problems, though.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
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