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.
--
Matthew Wilcox Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours. We can't possibly take such
a retrograde step."
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