Re: [PATCH] M68k IDE updates

[Geert Uytterhoeven]

On Mon, 14 Apr 2003, Paul Mackerras wrote:
> Alan Cox writes:
> > This looks the wrong place to fix this problem Geert. The PPC 
> > folks have the same issues with byte order on busses but you
> > won't see ifdefs in the core IDE code for it.
> > 
> > Fix your __ide_mm_insw/ide_mm_outsw macros and the rest happens
> > automatically.
> 
> As I understand it, on some platforms (including some PPC platforms,
> but not powermacs) one needs to byteswap drive ID data but not the
> normal sector data.  Or vice versa.  Whether drive ID data needs
> byte-swapping comes down to how the drive is attached to the bus.  The
> conventions used by other systems that we need to interoperate with
> (e.g. other OSes, or just older kernels) determine whether normal
> sector data needs byte-swapping or not.
> 
> Since __ide_mm_insw doesn't get told whether it is transferring normal
> sector data or drive ID data, it can't necessarily do the right thing
> in both situations.

Indeed. Ataris and Q40/Q60s have byteswapped IDE busses, but they expect
on-disk data to be that way, for compatibility with e.g. TOS.

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [e-mail]

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