Re: [RFC] libata new EH document

Jeff Garzik
2005-09-01T05:54:23Z

On Thu, Sep 01, 2005 at 02:44:00PM +0900, Tejun Heo wrote:
> Can you please elaborate why getting sense data from EH is bad idea
> for ATAPI? For more advanced SCSI transports, I agree with you that
> autosensing is necessary with queueing and multiple initiator and etc,
> but I don't really see how requesting sense from EH would be bad for ATAPI.

The long term direction for the SCSI core seems to be that of
requiring auto-sensing.

libata is simply being lazy: while the SCSI core continues to support
kicking the EH thread when sense is missing, it's preferred for libata
to reuse that infrastructure.

Auto-sensing (and READ LOG EXT for NCQ errors) requires either an
FSM or a kernel thread, to initiate a secondary qc for REQUEST SENSE.
Since the common infrastructure already exists for this, libata reuses
the existing SCSI EH kernel thread.

We should move libata-scsi to auto-sensing, but it's not an urgent priority.

Jeff