Re: CVS commit: src/sys/dev/ata

[David Laight <david%l8s.co.uk@localhost>]

On Wed, Oct 05, 2011 at 06:52:37PM +0200, Wolfgang Solfrank wrote:
> ...  You would tell the controller the cylinder/head/sector
> of the first sector you wanted to read, and when multiple sectors were
> requested, the controller would increment only the sector number.
> Since the controller wouldn't even know the number of sectors on a track,
> it wouldn't be able to cross a track boundary.

I suspect some PC BIOS/floppy have that 'feature'!
IIRC there is a bug booting from floppies with less than 8k/track
due to the way bootxx_xxxfs gets loaded.

There has been some confusion about the difference between reads for
multiple sectors and the 'multi-sector' read feature.
The latter changes the interface slightly - I think it means you
only get one data/dma request burst for multiple sectors.

With LBA reads the underlying (reported) geometry shouldn't matter.
But yes, avoiding requests for 256 sectors is probably a good idea!

        David

-- 
David Laight: david%l8s.co.uk@localhost