Write Protection Model

Takaharu Ai aiai at dsd.mei.co.jp
Fri Dec 17 23:59:14 PST 1999

* From the T10 Reflector (t10 at t10.org), posted by:
* Takaharu Ai <aiai at dsd.mei.co.jp>
Dear Kohda-san,

I ams sorry for late responce but we have some comments regarding Pioneer's write 
protection proposals.

Here are Matsushita's comments and counter proposal regarding Write Protection Model.

- In the Mt.Fuji3 specification, no information regarding a type and other property 
  of a medium in each slot is in the Slot Table Response format. The purpose of 
  this command is to obtain an information of the current situation of a "Slot" not 
  a disc. It means that a property of a medium shall be maintained by Host not 
  Logical Unit. So we think the extention in your proposal is not needed.

2) Event Reporting
- According to you proposal, Logical Unit shall generate Class 1 Event when the 
  Write Protection status is changed. But my understanding is that the Class 1 
  Event is generated when the Logical Unit's behavior is changed by for example 
  changing its microcode. But the Write Protection status is based on the disc not 
  the Logical Unit. Even if the PWP bit is changed to one by a command, no Feature 
  is added and no Microcode is changed. So we think the Class 1 is not appropriate.
- Our counter proposal is to generate Class 4 Event instead of Class 1 Event. 
  Because the changing of PWP is very similar to change medium.

3) Write Protection Feature
- The meaning that Feature which is returned by GET CONFIGURATION command is that 
  the function which is specified by the Feature is "supported" by the Logical Unit 
  regardless of the function is currently executable or not. In your proposals, the 
  Feature indicates that the Logical Unit can report the write protection status. 
  It means if the READ DVD STRUCTURE command with Format code C0h is "supported" by 
  a Logical Unit, this Feature shall be reported regardless of the command is 
  executable or not.
- The Current bit shall be set to one when the fucntionality indicated by the 
  Feature is currently executable. According to Pioneer's proposal, the Write 
  Protection Feature indicates to support the functionality to report the Write 
  Protection stauts of the medium though READ DVD STRUCTURE command with Format 
  code C0h. When a media is inserted, this command is executable I think. So the 
  Current bit is set to one when a writable medium is mounted.
- This is to clarify, but does the SWPW bit is set to one if the Logical Unit 
  "support" the READ DVD STRUCTURE command with Format code C0h even when the 
  mounted medium is write protected by the write protect tab on the cartridge?

Best Regards,

Takaharu Ai
Osaka, Japan

---Start of the original message ------------------------------------
>From: takeshi_kohda at post.pioneer.co.jp
>Date: Thu, 9 Dec 1999 18:05:48 +0900
>To: mtfuji2 at dt.wdc.com
>Cc: mmc at dt.wdc.com, t10 at t10.org
>Subject: Write Protection Model
>I have uploaded the revised Write Protection Model and related
>commands that were discussed at the December Mt.Fuji4 plenary meeting.
>The files are placed at the following FTP site:
>File names are:
>Wprtect.pdf   Write Protection Model
>Changer.pdf   MECHANISM STATUS Command
>Getcnfig.pdf  GET CONFIGURATION Command
>Rdvdstrc.pdf  READ DVD STRUCTURE Command
>Senddvd.pdf   SEND DVD STRUCTURE Command
>The newly changed portions to the current Mt.Fuji document
>are indicated by light blue color and change bars.
>Major revised items from the previous proposal are
>addition of Media Specific Write Inhibition status in
>Write Protection model and removal of PWP bit from the
>Because PWP is not a mechanism status but a disc status.
>If you have any comments, please respond to me or
>the reflector <mtfuji2 at dt.wdc.com> by Next weekend
>(December 17, Japan Time).
>I would like to know any idea widely.
>If there are no responses, these changes will be incorporated into
>the Mt.fuji4 Rev.0.8 draft document as is.
>Best Regards,
>Takeshi Kohda
---End of the message ------------------------------------------------
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