Write Protection Model

keiji_katata at post.pioneer.co.jp keiji_katata at post.pioneer.co.jp
Sun Dec 19 21:02:08 PST 1999


* From the T10 Reflector (t10 at t10.org), posted by:
* keiji_katata at post.pioneer.co.jp
*



  Hello all,

  I  got  comments  from  tree  persons.  I  think,  they  do  not  request
  significant  changes or rebuild the write protection model and method. So
  I decide that Write Protection materials can be included into Rev. 0.8 to
  discuss  totally.  But  I  would  like  to reply to the comments for more
  understanding.

  Hideki Takahashi, <hidy.takahashi at toshiba.co.jp>
  wrote:-------------------
  This is Hideki Takahashi from Toshiba.

  In  the  Write  Protection  model,  could you please change the following
  part?

  Before change:
  "In  the  case of DVD-RAM media, there is Media Specific Write Inhibition
  (MSWI). It is controlled by Disc Type Identification field of the Lead-in
  physical  format  information.  When a DVD-RAM medium is removed from the
  cartridge,   and   if  any  recording  is  inhibited  by  the  Disc  Type
  Identification  field,  MSWI  is set to active status. See 4.14.14,"Write
  Protection of a disc" on page99."

  After change:
  "In  the  case of DVD-RAM media, there is Media Specific Write Inhibition
  (MSWI). See 4.14.14,"Write Protection of a disc" on page99." ?

  I  will  prepare  the  document about the write-inhibit status in the RAM
  part.
  -----------------------------------
  My  question  is  what is bad potion in the "Before". I think this is not
  technical issue and can be fixed in the short discussion.


  Kenji Tokumitsu, <tokumitsu at cm.tookai.hitachi.co.jp> wrote:-------------
  Dear Mt.Fuji members,

  I am Kenji Tokumitsu of Hitachi.
  We  would like to explain our comments to the proposal of Pioneer noticed
  on December 9th with the attached file.
  Could you consider our comments also.
  Thank you and ahve a nice weekend !

  Kenji Tokumitsu
  In commentp.pdf:
  The BDWI(Bare Disc Write Inhibited) bit of one indicates that the disc is
  not permitted the write operation without a cartridge.
  ------------------------------------------
  This  issue  was  discussed  in  December  meeting. The conclusion is "In
  DVD-RAM  model  section  and Format code 09h, the DVD-RAM own information
  shall be described".


  Takaharu Ai, <aiai at dsd.mei.co.jp> wrote:-------------------

  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.

  1) MECHANISM STATUS command
  -  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
  extension 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 functionality 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  status  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
  SDBD/AVC/MEI
  Osaka, Japan
  ------------------------------
  About  "1) MECHANISM STATUS command", so I remove PWP from the Slot Table
  Response  format.  The  CWP  in  the  Slot Table Response format provides
  "Partial  Medium Load for MAM Access" like functionality. Some device can
  read CWP status without loading the cartridge into its play position.

  About  "2) Event Reporting", I disagree completely. 1st reason is this is
  class  1  event, not class 4 event. 2nd reason is reporting class 4 event
  may  confuse the system. Usually the system which supports writing on the
  media  by particular file system shall supports reading the media and the
  used file system. There is no advantage useing class 4.

  About "3) Write Protection Feature", I may not understand the all meaning
  of  this  comment.  But  it  may  be as follows. Reading write protection
  status  and  Setting  write  protection status shall be separated same as
  "Random  Readable  Feature"  &  "Random  Writeable  Feature".  But  it is
  redundant,  it is too much for such a write protection issue, I think. If
  no  media status or ROM media in the device is defined as write protected
  status because any write shall be failed, reading write protection status
  can  be  "Persistent".  But  in December meeting, we decided that without
  media,  Read  DVD  Structure  command  with  format  code  C0h  shall  be
  terminated with Check Condition. Then it is not Persistent.
  However,  there  is  no  need to use current bit to show "you can see the
  write  protection status now". Because if media is installed, you can see
  the  write  protection  status that is defined by the media specification
  always.

  Anyway, we can discuss and fix them in January meeting.

  Best Regards.

  Keiji Katata
  PIONEER CORP.


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