[Slackbuilds-users] About vlc SBo

Christoph Willing chris.willing at linux.com
Thu Nov 15 04:13:22 UTC 2018

On 6/11/18 9:07 pm, Luiz Carlos Ramos via SlackBuilds-users wrote:
> Hello,
> This email is to tell about a problem in building vlc and how it could
> be worked around.
> I was just updating a system here (x86_64 with multilib), running
> SlackBuilds manually to rebuild some old packages and experienced a
> problem with the binary vlc generated, which gave segfaults
> systematically.
> I tried to analyze the problem and found a piece of code inside
> pulseaudio which calls shm_open() (which is supplied from librt.so).
> Going further, I found that shm_open() tries to call __shm_directory()
> and this function - which is inside libpthread.so - is not correct
> linked for some reason. When the call is tried, the segfault
> happens.
> (yes, to find it I have to google a little; this article showed the
> trick:
> https://stackoverflow.com/questions/47905554/segmentation-fault-appears-when-i-use-shared-memory-only-from-statically-build-p)
> I could find a way to work around it. The vlc binary, as it was built in
> the machine, required libpthread.so but not librt.so (verified by
> calling objdump -x vlc). I managed to add librt.so in the final link
> (using SLKLDFLAGS="-lrt") and the resulting vlc added librt.so as a
> "NEEDED" dependency. Installing the package, the problem was gone.
> Of course this is not happening in the majority of the installations,
> but as it happened here, it can happen anywhere.
Hi Luiz,

Thanks for diagnosing the problem and suggesting a fix. I've never seen
that problem myself but you're right that it could happen anywhere so
I've just pushed an update which sets SLKLDFLAGS="-lrt".


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