Write Protection Model
tokumitsu at cm.tookai.hitachi.co.jp
tokumitsu at cm.tookai.hitachi.co.jp
Tue Dec 21 05:30:06 PST 1999
* From the T10 Reflector (t10 at t10.org), posted by:
* tokumitsu at cm.tookai.hitachi.co.jp
*
Dear Katata-san,
I am Kenji Tokumitsu of Hitachi.
I cannot understand the commnet from Ai-san of MEI and your response about
the Write Protect Feature.
So, I am sending my comment about the Write Protect Feature.
The definition of the Write Protect Feature proposed by Pioneer looks
strange.
The definition is "This Feature shall indicates that the Logical Unit can
report the write protect status.".
According to this definition, I think that the Current bit shall be set to
one when the Logical Unit can report write protect status, even if the
Logical Unit cannot change the PWP status for mounted medium.
But, there is a description that "the Current bit shall bet to zero if the
Logical Unit can not set/release the PWP status on the mounted media
surface.", in the proposal.
In case of DVD-RAM drive, the drive will support both 2.6GB DVD-RAM media
and 4.7GB DVD-RAM media. The Write Inhibit Flag is not exist on 2.6GB DVD-
RAM media. However, the drive can report write protect status for 2.6GB
DVD-RAM media. So, the Current bit shall be set to one for 2.6GB DVD-RAM
media. But, according to the proposal of Pioneer, the Current bit shall
be set to zero for 2.6GB DVD-RAM media, because the PWP status of 2.6GB
DVD-RAM media is not changeable.
It looks strange.
So, I think that the definition of the Write Protect Feature should be
changed as follows.
----
This Feature shall indicate that the Logical Unit is capable of changing
the PWP status. This Feature shall be applied to Random writable or
Overwritable Logical Unit only.
The READ DVD STRUCTURE Command with Format code C0h and FFh and the SEND
DVD STRUCTURE Command with Format Code C0h shall be supported.
----
And the SPWP bit in Table 118 and the following descriptions are not
necessary.
----
The Supports PWP(SPWP) bit indicates that the Logical Unit supports set/
release PWP status. If SPWP bit is set to one, the SEND DVD STRUCTURE
Command with Format=C0h shall be supported.
----
Best Regards,
Kenji Tokumitsu
___________________________________ $BJV?.(J _______________________________________
$B7oL>(J: Re: Write Protection Model
$BAw?.<T(J: <keiji_katata at post.pioneer.co.jp > at ~hitachi-tookai-cm
$BF|IU(J: 1999/12/20 14:02
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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