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

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