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about imx6 dvd-rom

Question asked by lian jianfei on Jul 25, 2014

Have anyone use the freescale board try the dvd-rom function? I try to use the software libburn to burn dvd,but it seems doesnot work.

And here is the software editor's reply:

  > linux3.0.35 is tested on the ARM (freescale imx6q) which occurs the problem.


So for now i would suspect an ARM architecture specific problem

which is triggered by the SCSI command sequence beginning at line

198 of the log file:




First an GET CONFIGURATION command is issued with a sparse reply

buffer size in order to learn the necessary size for this buffer:



  46 00 00 00 00 00 00 00 08 00


Similar to a previous occasion in line 95 of the log file, libburn

gets an answer from the drive


  From drive: 8b

  00 3a 41 00 00 00 00 00

       1062 us     [ 3021392 ]


Different from the answer to line 95, the announced size is

unrealistically large:     0x003a4100 = 3817728 decimal.

The answer for line 95 was 0x0000019c = 412 which is plausible.

My test drive Samsung CDDVDW SH-S203B tells 0x00000158 = 344.


With this unrealistic size request, the command is performed

again in order to obtain the list of MMC profiles, which would

tell the supported media types and states.


The MMC command GET CONFIGURATION only has two bytes for

telling the drive the requested amount of data. 4 bytes have

to be added. So  0x003a4100 gets truncated to 0x4100 and

then added up to 0x4104:



  46 00 00 00 00 00 00 41 04 00


Already this smaller size causes the protest of the operating system


  cdrskin: ( Most recent system error: 22  'Invalid argument' )

  --- SG_IO: return= -1 , errno= 22 , host_status= 0x0 , driver_status= 0x0


which would be bad enough. But obviously it also spoiled some

dynamic memory, which soon later causes the program crash.


  cdrskin: malloc.c:3096: sYSMALLOc: Assertion ...




I will augment libburn to recognize such clearly ill size announcements.

Regrettably it will then only have the option to perform an emergency

end. The only advantage will be a clearer error message and no memory

fault at program end.


You should now look for advise by the people who maintain that ARM

Linux kernel. (I assume CD drives are an exotic add-on to this kind

of machine.)

Show them my above diagnosis and eventually the cdrskin_scsi.log file.

Tell them that the SCSI commands are specified in SCSI documents SPC-3,

SBC-2, and MMC-5.

I dont understand the scsi command tranfered form the linux kernel to the driver and


why it comes to the problem,so waiting for your help.And the software presents the


scsi command is sent.

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