Re: [PATCH] make the SCSI mid-layer obey the device online flag

[Luben Tuikov <tluben@rogers.com>]

James Bottomley wrote:
> On Fri, 2003-06-06 at 11:28, Luben Tuikov wrote:
> 
>>James was talking about ``device server not ready'' aliased to
>>online -- i.e. if online is 0 then only INQUIRY or TUR should
>>be sent from SCSI Core (unless SCSI Core decides to _know_ about
>>the different ULP).  The semantics on this are somewhat touched
>>in the INQUIRY description in SPC-3.
> 
> 
> Actually, not just TUR and INQUIRY.  Think about errors on removable
> media: we offline the device because of them and now the user needs to
> unlock the door and eject the cartridge...
> 
> Thus, we allow any special command because we assume it's part of error
> handling (or post error clean up).

So SCSI Core _has_ decided to know about ULP (block, tape, optical).

Unless we (SCSI Core) generate those, it's a pickle to decide
which are ``special'' enough commands.  I think that we'll see
more user space drivers controlling devices via sg sending
commands to the device for exactly those kinds of problems...
Else the burden on SCSI Core will/might be too great.

-- 
Luben