[k3b] [Bug 257602] K3B cannot burn Blurays (or AVCHDs)

[Thomas Schmitt]

https://bugs.kde.org/show_bug.cgi?id=257602

--- Comment #29 from Thomas Schmitt <scdbackup at gmx.net> ---
Hi,

i can reproduce the cdrskin problem by configuring libburn with option
  --enable-track-src-odirect

The bug is a regression from end of 2009 by release 0.7.4, when cdrskin
forgot that it must prepare special buffer memory by mmap(2) when libburn
is configured to do O_DIRECT.

Many thanks to King_DuckZ for reporting it.
But i still need to know from where the cdrskin binary stems and, if it's
not the standalone version, from where libburn.so (aka libburn4.so) stems.

The proposed workaround really avoids the problem here:

  cdrskin -v dev=/dev/sr0 fs=32m -eject -waiti - <image.udf

(Tested cowardly with a BD-RE medium. I still owe you a BD-R medium.)

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growisofs does not show the problem, because its memory preparations suffice.
(Reading articles about O_DIRECT raises concerns about whether these
 preparations will always succeed.)

xorriso does not show the problem because it uses the built-in fifo of
libburn, which did not yet exist when cdrskin was founded in 2006.
This fifo knows how to prepare its buffer for O_DIRECT.

Nevertheless, the situation is tricky. libburn and its applications could
by several ways get out of sync in this aspect.
So now i am pondering whether to completely drop the opportunity in libburn
to use O_DIRECT.

Have a nice day :)

Thomas

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