[Stgt-devel] Prototype MMC DVD-ROM and burnable DVD+R implementation

ronnie sahlberg ronniesahlberg
Mon Apr 14 12:25:10 CEST 2008

Hi List

Please find attached a "small" (nothing is small when it comes to mmc)
patch to the MMC emulation that adds
support for three different profiles
1, NO_PROFILE    which is triggered by the lun being offline and
causes the emulation to behave as a dvd drive with no disk in the bay.
2, PROFILE_DVD_ROM   which is triggered by the backing store being >0
bytes in size when the lun is brought online.
   In this mode it behaves as a DVD drive with a ROM disk in the bay.
Reads are honoured but nor writes. It reports that the media contains
embossed data.
3, PROFILE_DVD_PLUS_R which is triggered if the backing store file is
==0 in size when the lun is brought online. In this mode it behaves as
a DVD drive with a blank
    writeable +R disk is in the bay.

In the +R profile,  I have tested it with DVDDecrypted from windows
and it works well. I can write/burn iso images to this +R dvd disk.
Once the disk is burned and the application finishes the process by
issuing the CloseTrack CDB, the emulation will "morph" the device and
change the mode into being DVD_ROM instead.

There are controversial changes to the core in this patch wich
involves changing of how online/offline is handleded and also adds the
possibility to add a LUN with a nonexisting backing store
(the lun will be created but it never goes online).

These changes, which are a small part of the diff, is likely to break
other non MMC device emulations  so you may NOT want to import this
patch as it is into the tree.

But please feel free to review and comment on it.

The emulation adds several large MMC CDBs but only adds what is
required for DVD_ROM and DVD+R profiles to wurk under DVDDecrupter
when burning an iso to a blank disk.
Later it will be necessary to add emulation of additional CDBs and
fields in CDBs to enable other dvd burning tools to work as well.
It is only tested with DVD decrypter and it sworks well.

Now, the next question, would STGT want to have DVD_ROM/DVD+R emulation?
If so, how should i proceed?   the patch is pretty (>2.6k lines) big
since MMC is pretty enormous.
What is the next step i need to do now, once i have shown a working prototype?
(feel free to test it out, but dont add it to the git tree until the
controversial parts have been resolved)

I am willing to rework the patch into smaller pieces,
maybe one piece with the online/offline changes, then one patch for
each MMC CDB that is added ?


ronnie sahlberg
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