Re: Subject: [PATCH RFC] block: fix Amiga RDB partition support for disks >= 2 TB

Geert Uytterhoeven
2018-06-29T08:51:12Z

Hi Michael,

On Fri, Jun 29, 2018 at 10:43 AM Michael Schmitz <schmitzmic@gmail.com> wrote:
> Am 28.06.18 um 21:25 schrieb Geert Uytterhoeven:
> >>> Do we really need the warning?
> >>> Once the parsing is fixed doing 64-bit math, it does not matter for
> >>> Linux anymore.
> >> Well, irony of this is: In my case the RDB has been created on a machine
> >> with a native OS. So Linux warns me about something I already did so on
> >> the native OS without any warning. In this case AmigaOS 4.0.
> > Exactly.
> >
> > So moving a disk partitioned under AmigaOS 4.0 to a system running an
> > older version of AmigaOS can fail miserably. Not a Linux issue.
> > Linux also doesn't warn about disks with GPT failing to work on old MSDOS.
>
> Would MSDOS recognize the GPT partition as 'probably FAT', and attempt
> to use it?

No idea...

Probably some old Windows or MacOS versions will just suggest to
format your "new" disk ;-)

But it's up to the person (which is not Linux) formatting the disk to
not try to use
it on systems that cannot handle it, and may destroy it.

> > Let me clarify: what exactly would the kernel option allow? When to use it?
>
> Whether to use it if safe (on Linux). But whatever Linux does (after
> this patch), access will go to the right area of the disk (as specified
> by the RDB) so Linux won't any longer stomp on anything that would have
> mattered to 32 bit disk drivers. So it really should be safe.

Personally, I see no reason to depend on a kernel option, if it is safe to use.
Just use it.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds