Re: [PATCH] only use 48-bit lba when necessary

[Jens Axboe <axboe@suse.de>]

On Fri, Apr 04 2003, Andries Brouwer wrote:
> On Fri, Apr 04, 2003 at 02:29:36PM +0200, Jens Axboe wrote:
> 
> > 48-bit lba has a non-significant overhead (twice the outb's, 12 instead
> 
> s/non-// ?

Of course :)

> > of 6 per command), so it makes sense to use 28-bit lba commands whenever
> > we can.
> > 
> 
> > +	if (drive->addressing == 1 && block > 0xfffffff)
> > +		lba48 = 1;
> 
> Hmm. I wonder whether we should be more cautious, and ask for lba48
> as soon as some part of the interval is past this limit.
> (say, block+nsectors > 0xfffffff)
> 
> I don't know whether the standard spells out what happens
> at the boundary, but for example the LBA low/mid/high, DEV is required
> to contain the sector number at the place the error occurred,
> and that is possible only if one stays below the 28-byte sector limit.

That might not be a bad idea, just to be on the safe side. I'll do that.

-- 
Jens Axboe