[Cbe-oss-dev] PS3 and CD playback

[Geoff Levand]

Ben,

Below are some notes from Mokuno-san regarding the Linux CDDA playback bug.
This info is from last November and the 2.6.16 kernel.  I don't know the
status of the 2.6.21 kernel.

-Geoff


Linux CD-ROM middle layer has a severe bug about handling READ_CD command.
If application requests more frames (i.e. audio sectors = 2352 bytes) than 
the mid layer can queue in one command,  the middle layer will crash
or hang the kernel.

You can reproduce this bug (even with x86 PC) as following

1)  Attach USB CD drive to Linux box.  Assuming
     its device node is /dev/scd0 in the followings.
    # ls -l /dev/scd0
    brw-rw----  1 root disk 11, 0 Nov 29 00:08 /dev/scd0
2)  Change maximum sectors  parameter like as following:
    # find /sys -name max_sectors
 
/sys/devices/pci0000:00/000:00:04.2/usb1/1-1/1-1:1.0/host1/target1:0:0/1:0:0:0/max_sectors
    # echo 32 >`find /sys -name max_sectors`
3)  Start to extract CDDA tracks 
    # cdda2wav -B -D /dev/scd0
Then system will hang or crash. 
With my experence, usually x86 PC  will hang, ps3 will get BUG().

The default max_sectors value of ps3 storage driver is 32, so enabling 
READ_CD command of  ps3 driver triggers this bug without changing
max_sectors parameters.  Enlarging the default value solve this issue
temporally, but if the  application requests more frames  in the future,
the bug will occur again.

Finally, cdparanoia apparently does not check error code when extracting
audio tracks.  It continues extracting even if the driver returned 
'ILLEGAL REQUEST'.  That is another cause useless audio files were created.

-EOF