undefined reference to `shm_open'

Carlo Zinato c.zinato at viscount.it
Tue Dec 15 17:06:13 UTC 2009


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.

Regards,

-- 
Carlo Zinato
Viscount International S.p.A.
R&D Labs, Ancona, Italy
phone & fax +39 071 2905127 / 2905142
e-mail: c.zinato at viscount.it
skype: carlo_rd_viscount


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