Re: CVS commit: src/sys/dev/ata

[Dave Sainty <dave%dtsp.co.nz@localhost>]

Manuel Bouyer writes:

> On Sat, Jul 02, 2005 at 04:29:01AM +0000, David Sainty wrote:
> > [...]
> > [An alternative approach is to just always drop to LBA48 if the request
> > happens to pass by sector 0xfffffff and the drive reported as larger than
> > 0xfffffff sectors.  My understanding is that the 32 bit addressing below
> > 0x10000000 is purely there as a performance booster, not to resolve a
> > compatibility issue.]
> 
> It is. Some controllers can't do LBA48 properly. Large drives on such
> controllers currently work fine if limited to 128GB.

They wouldn't be any worse off under the suggested scheme.  If they
happen to have one of the crash-on-0xfffffff drives on such a
controller they STILL couldn't use that sector, because then the drive
would be crashing now.  And under the suggested scheme they would
still be able to use the rest of the lower 128GB, like you suggest.

However, under the existing scheme, a person with a drive in the
forced LBA48 list could NOT use that drive with a controller that
can't do LBA48.  But under the suggested scheme those people would be
able to use the lower 128GB like you suggest.

So your scenario is perhaps more an argument for change than one for
leaving it as is?

Cheers,

Dave