On Thu, 25 Jun 2009, Martin K. Petersen wrote:

Neil> So I asked git why it as added, and it pointed to
Neil>   commit 1308835ffffe6d61ad1f48c5c381c9cc47f683ec

Neil> which suggests that it was added so that user space could tell the
Neil> kernel whether the device was rotational, rather than the other
Neil> way around.

There's an option to do it via udev for broken devices that don't report
it.  But both SCSI and ATA have a setting that gets queried and the
queue flag set accordingly.

.. except few devices actually set it. 

That flag is _definitely_ all about the user being able to override it.

		Linus