Re: [PATCH] pktcdvd & udf bugfixes

From: Phillip Susi
Date: Sat Jan 14 2006 - 13:36:44 EST


Peter Osterlund wrote:


The variable is unsigned, so it supports values up to 255, ie no need
to change it.



The packet length is read and left shifted by two before being stored in that variable to convert it from 2048 byte sectors to 512 byte sectors, thus a value of 128 overflowed and became zero. be32_to_cpu returns a 32 bit value so I figured it should be stored in a 32 bit variable, not an 8 bit one.


That code is very old, I think Jens wrote it. I assume it wasn't just
for fun, but to be able to support drives with slightly
broken/non-standard firmware.



Yes, I hope he can let me know if that is the case, but right now I do not see how that can be. As far as I know, that value is put there by the utility used to format the track, and _should_ be the correct length, never 0. In any case, if it is zero, then assuming the maximum supported size would cause errors if the actual packet size is larger than the maximum that the driver supports.


The current limit is 32 disc blocks, ie 64KB or 128 "linux sectors".

How do you make the packet size larger for a CDRW disc? Just changing
the constant is not going to help unless you can also format a disc
with larger packets.



I also have several patches to the udftools package, one of which documents ( in the man page ) the previously undocumented -z packet_size parameter to cdrwtool, and fixes the code so that it actually works with values other than 32.

The upstream project for udftools on sourceforge appears to be dead. I have sent email to the two original authors and had no reply, and the CVS repository has not been touched in over a year, and the mailing list is dead. I am not sure what I should do about that, but in the mean time, I am maintaining ubuntu specific patches and have been speaking to the debian package maintainer about merging them there as well.


Might be a good idea. On DVD discs the block size is only 32KB, so
half of the allocated memory is unused.


Why is it only 32 KB on a dvd? What utility was used to format it like that? My cd/dvd-rw drive blew out the cd laser the other day, and I got the replacement last night with some dvd+rw media, so I guess I will start playing with that soon. From what I have read so far, dvd+rw media does not require pktcdvd to write to it, but its use can improve throughput.

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