undefined reference to `shm_open'

Carmelo AMOROSO carmelo.amoroso at st.com
Wed Dec 16 07:07:54 UTC 2009


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Carlo Zinato wrote:
> Il 15/12/2009 17.31, Niko Lau ha scritto:
>> 2009/12/15 Lennart Sorensen<lsorense at csclub.uwaterloo.ca>:
>>> On Tue, Dec 15, 2009 at 05:16:05PM +0100, Niko Lau wrote:
>>>> I want to use the libv4l2 for my arm platform with uclibc cross
>>>> compiler.
>>>> When I link a appl with that lib I get the following error:
>>>> arm-linux-uclibc-gcc -Wall -O2 -g -I../libv4l2/include
>>>> -L../libv4l2/lib  -o capture capture.c -lv4l2 -lv4lconvert
>>>> ../libv4l2/lib/libv4lconvert.so: undefined reference to `shm_open'
>>>> collect2: ld returned 1 exit status
>>>> make: *** [test] Fehler 1
>>>>
>>>> The lib is built with the same compiler without any error.
>>>> Can someone give me a hint what the problem is. Since it works with a
>>>> glibc compiler i think the problem is the uclibc.
>>>
>>> The man page (for the glibc version) says you have to link with -lrt.
>>> I don't see you doing that.  Do you have to?  Does uclibc have such
>>> a thing and does it do shm_open?  I guess it must or the header files
>>> would have failed yoiur earlier compile already.
>>>
>>> -- 
>>> Len Sorensen
>>>
>>
>> The -lrt flag is set during libv4lconvert building. I can see shm_open
>> in the include file (/sys/mman.h)
>> so i think uclibc has shm_open.
>>
>> Niko
> 
> Hi Niko, you may read the threads:
> 
> http://lists.uclibc.org/pipermail/uclibc/2006-December/037885.html
> http://lists.uclibc.org/pipermail/uclibc/2007-July/039125.html
> http://lists.uclibc.org/pipermail/uclibc/2009-February/041886.html
> http://lists.uclibc.org/pipermail/uclibc/2009-June/042541.html
> 
> As last uclibc's release is "2 March 2009, uClibc 0.9.30.1", I'm not
> sure ( but I could be wrong ) that full shm support has been already
> included.
> 

that's right.

> Regards,
> 

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