On Thu, Apr 23 2009, Matthew Wilcox wrote:
> On Thu, Apr 23, 2009 at 12:51:45PM +0200, Jens Axboe wrote:
> > > +/**
> > > + * blk_queue_alignment - set alignment for the queue
> > > + * @q: the request queue for the device
> > > + * @alignment: alignment offset in bytes
> > > + *
> > > + * Description:
> > > + * Some devices are naturally misaligned to compensate for things like
> > > + * the legacy DOS partition table 63-sector offset. Low-level drivers
> > > + * should call this function for devices whose first sector is not
> > > + * naturally aligned.
> > > + */
> > > +void blk_queue_alignment(struct request_queue *q, unsigned int alignment)
> > > +{
> > > + q->alignment = alignment & (q->granularity - 1);
> > > + clear_bit(QUEUE_FLAG_MISALIGNED, &q->queue_flags);
> > > +}
> > > +EXPORT_SYMBOL(blk_queue_alignment);
> >
> > How would low-level drivers know?
>
> ATA reports this in the INQUIRY data. SCSI reports it in READ CAPACITY 16.
OK, I wasn't aware of that. That's a relief!
--
Jens Axboe
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