Re: [PATCH] M68k IDE updates

From: John Bradford (john@grabjohn.com)
Date: Wed Apr 23 2003 - 15:19:07 EST


>
> On Mer, 2003-04-23 at 12:27, Richard Zidlicky wrote:
> > It seems that Geert=C2=B4 idea would fit neatly into the current IDE=20
> > system. Endianness of on disk data and drive control data are
> > clearly different things. A while ago Andre suggested to switch
> > the transport based on opcode to make it work, it might be even
> > more straightforward to set some flag when the handler is selected
> > or take a distinct handler altogether (ide_cmd_type_parser or
> > ide_handler_parser).
>
> Thats over complicating stuff I think.
>
> > Otoh trying to solve that with loopback would mean new kernels=20
> > wouldn=C2=B4t even see the partition table of old installed harddisks
> > on some machines.=20
>
> Which is a real pain. I think its the right 2.5 answer. I'm not happy
> about breaking that (even if its only for the m68k userbase in 2.4)
> either.
>
> I don't think command parsing is the right place. Turn your IDE layer
> "right endian" and most stuff begins to look a lot saner already.=20
> The "fixing" needs to be happening at the top of the IDE layer not
> in the driver itself. For 2.5 that ought to be loopback or similar
> for 2.4 it makes sense I think to effectively implement an endian
> switcher without loopback for compatibility.

Moving byte swapping out of the IDE layer also means that dumping the
whole disk to a file will then give you non-byte swapped data, which
could then be written back to a disk on another machine without a
byte-swapped IDE interface.

It will also allow you to exchange tar archives on raw hard disk
devices, and have them readable on non-byte swapped IDE interfaces
:-).

John.
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