Re: [PATCH 1/2] scsi: Add scsi_device max_cmd_len

[Brian King <brking@us.ibm.com>]

Jeff Garzik wrote:
> James Bottomley wrote:
>> This really doesn't look correct.  What you want is a sata transport
>> class with a max command length in the host device.
> 
> Christoph Hellwig wrote:
>> this sounds wrong to me.  cdb length is a limitation of the host (driver).
>> A target will reject unknown commands, no matter what length they have.
> 
> 
> In practice, CDB length may be limited by both the host and the device. 
>   This applies to ATAPI, and some USB storage too IIRC.  For ATAPI, you 
> read the CDB length from the device's IDENTIFY PACKET DEVICE info page.

So the question remains, do we need to police the CDB length on a per device
basis, or is a per host basis ok? Will we have ATAPI devices falling on the
floor if they get sent too large of a cdb?

Brian

-- 
Brian King
eServer Storage I/O
IBM Linux Technology Center