Re: [PATCH 2.6.20-rc3] fix broken retval test in sr_block_ioctl

[Mark Lord <liml@rtr.ca>]

Jeff Garzik wrote:
> Mark Lord wrote:
..
>> Allow ATA_12 / ATA_16 passthru commands to be issued for ATAPI devices
> 
> Douglas Gilbert noticed this a while ago.
> 
> The patch's technical content is fine, but there is an open policy 
> question:  For some devices, there is an opcode overlap (BLANK?  Doug 
> probably remembers the issue better than I).  And from a practical 
> standpoint, to handle any vendor weird-isms (nahhh those never happen in 
> ATAPI), it would be nice to be able to force the current (pre-mlord 
> patch) behavior to ensure that all opcodes are passed to ATAPI.
> 
> Absent a better idea, I would simply suggest adding a module parameter 
> that restores the "all opcodes are passed to device, guaranteed" mode.
> 
> I'm fine with changing the default behavior to that which is presented 
> by your patch.

Mmmm.. yes, the "BLANK" opcode is indeed the same as ATA_12.
That looks rather dangerous to me -- isn't BLANK commonly used
with CD-RW discs and the like?  (gotta test that now..)

If so, then perhaps all we can support is ATA_16, except the upper
layers mightn't even pass them to libata without a bit of hackery.

I'll go and see about BLANK now..

Cheers

Mark