Re: CD writing in future Linux (stirring up a hornets' nest)

[Joerg Schilling]

Matthias Andree <matthias.andree@xxxxxx> wrote:

> Joerg Schilling wrote:
>
> >> So I'll repeat my question: is there anything that SG_IO to /dev/hd* (via
> >> ide-cd) cannot do that it can do via /dev/sg*? Device enumeration doesn't count.
> > 
> > But device enumeration is the central point when implementing -scanbus.
>
> Again: Is there anything *besides* (<German>: außer) device enumeration that
> does not work with the current /dev/hd* SG_IO interface?

This is the main point.

People like to run cdrecord -scanbus in order to find a list of usable devices.
People like to see all SCSI devices in a single name space as they are all 
using the same protocol for communication.

A sane way to send SCSI commands to _any_ type of devices would be to have a 
SCSI generic transport layer that is independent from the high-level features 
of the OS and that is independent from whether there is a high-level driver for 
this device at all.

This is what I designed the scg driver interface for in 1986 and this is what
Adaptec did in 1988 with ASPI. This is of course also why the SCSI standard 
commitee made a proposal for the CAM SCSI interface. 

http://www.t10.org/ftp/t10/drafts/cam/cam-r12b.pdf
http://www.t10.org/ftp/t10/drafts/cam3/cam3r03.pdf

Jörg

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