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Re: dvd+rw-tools 7.0: iso burning problem

I faced a problem with dvd+rw-tools (6.0, 6.1 und 7.0) when I tried to burn a DVD-Iso-Image to a dvd using the command line

growisofs -Z /dev/scd2=/media/CDWserver/export/Server/DVD-Images/KNOPPIX_V5.0.1DVD-2006-06-01-DE.iso
But it gives an invalid argument error:
---- Output
Executing 'builtin_dd if=/media/CDWserver/export/Server/DVD-Images/KNOPPIX_V5.0.1DVD-2006-06-01-DE.iso of=/dev/scd2 obs=32k seek=0'
:-( write failed: Invalid argument
The following command line works well:

cat KNOPPIX_V5.0.1DVD-2006-06-01-DE.iso | growisofs -Z /dev/scd2=/dev/fd/0

Why is there is difference between these two commands. Why does the second work and the first not?

I'd bet on the fact that growisofs opens file with O_DIRECT, while cat doesn't.

For public reference. It turned to be the problem with ext3 implementation under 2.4 missing direct I/O method, which appears to be trivial [and erroneous] omission in kernel source [at lest ext2 implements this method]. One would normally expect O_DIRECT flag rejected already at open(2), but it doesn't seem to be the case. It remains mystery why it was not noticed earlier by 2.4 users. Next version shall compensate for this by banning O_DIRECT under 2.4 [naturally at run-time]. Meanwhile those who suffer from this can modify #ifdef O_DIRECT line in growisofs.c as #ifdef __notdef__ to work around the problem. A.

P.S. for Marcus. The final conclusion slightly differs from one I gave you in private conversation, but it the workaround is the same.

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