Re: [Bug-xorriso] Formating of DVD-RAM fails

[Thomas Schmitt]

Hi,

> cat /proc/sys/dev/cdrom/info
> says to some drives I own it can read MRW but the official
> spec from the manufacturer says no or nothing about it.

I assume that Linux gets its info from SCSI command
GET CONFIGURATION, which would report feature 0x28.
My oldest DVD burner says 

  ... 00 28 00 04 01 00 00 00 ...

MMC-5, 5.3.18, "The MRW Feature":
Byte 4 holds three flags:
bit0= "CD Write", bit1= "DVD+ Read", bit2= "DVD+ Write".
So this drive claims to only do MRW on CD-RW media.

None of my three BD drives reports feature 0x28 at all.


Feature descriptor found by

  $ xorriso -scsi_log on -outdev /dev/sr0
  ... look for "GET CONFIGURATION" with large "From drive:"
      (first comes a peek command with only 8 bytes of reply)
      Read the data according to to MMC-5, 5.2:
        skip 8 bytes header 
        loop:
           consume next four bytes,
           plus as many as the last byte of these 4 tells,
        until the first two bytes say "00 28"

This blob tells what media profiles the drive can handle,
what profile is currently activated by the loaded medium
type, and what other features the drive offers to its
driver.


Have a nice day :)

Thomas