On Wed, 4 Jul 2012, James Bottomley wrote:

quoted

The reason for the try_rc_10_first flag is that some devices return
bogus data in response to RC16.  Like, an 800 GB device claiming to
have 3 exabytes.

So we could easily send both and only believe RC10 if the device is
under 2TB.

More precisely, if RC10 indicates the device is under 2 TB then ignore 
the RC16 capacity.  Or maybe issue a warning if it disagrees with the 
RC10 capacity.

 However, what about all the extra flags we read out of RC16,
like trim, large sector size and DIF capability?  If the device lies
about its capacity, won't we get bogus values for those as well, which
is going to cause other screw ups?

That seems quite likely.  I don't know the answer for any individual 
cases, however.

For the greatest safety, I suppose we could disbelieve all the fields 
in the RC16 response if the RC16 capacity disagrees with the RC10 
capacity and the RC10 capacity is under 2 TB.

Alan Stern