Configure script doesn't find Linux headers - Debian Wheezy

[piotrjurkiewicz]

Trying to configure Click on the present stable Debian (Wheezy) I get the following error:

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Can't find include/linux/skbuff.h in /lib/modules/3.2.0-4-686-pae/build.
Are you sure /lib/modules/3.2.0-4-686-pae/build contains Linux kernel source?
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I assume that the problem is connected with a (not so) recent (2009) change in kernel headers packages in Debian. Symbolic links for the common headers are no longer included in the flavour-specific headers directory. Click configure script tries to find headers in /lib/modules/VERSION/build directory, which links to the the flavour-specific headers directory. However, these headers are located under /lib/modules/VERSION/source. It is shown below.

root@router:/click-src# ls -la /lib/modules/3.2.0-4-686-pae/
total 3012
drwxr-xr-x  3 root root   4096 Dec 30 01:29 .
drwxr-xr-x  3 root root   4096 Dec 30 00:17 ..
lrwxrwxrwx  1 root root     38 Sep 20 14:39 build -> /usr/src/linux-headers-3.2.0-4-686-pae
drwxr-xr-x 10 root root   4096 Dec 30 00:17 kernel
-rw-r--r--  1 root root 722637 Dec 30 00:17 modules.alias
-rw-r--r--  1 root root 703931 Dec 30 00:17 modules.alias.bin
-rw-r--r--  1 root root   3034 Sep 20 14:30 modules.builtin
-rw-r--r--  1 root root   4158 Dec 30 00:17 modules.builtin.bin
-rw-r--r--  1 root root 351952 Dec 30 00:17 modules.dep
-rw-r--r--  1 root root 488548 Dec 30 00:17 modules.dep.bin
-rw-r--r--  1 root root    325 Dec 30 00:17 modules.devname
-rw-r--r--  1 root root 117483 Sep 20 14:30 modules.order
-rw-r--r--  1 root root    131 Dec 30 00:17 modules.softdep
-rw-r--r--  1 root root 287376 Dec 30 00:17 modules.symbols
-rw-r--r--  1 root root 365247 Dec 30 00:17 modules.symbols.bin
lrwxrwxrwx  1 root root     37 Sep 20 14:39 source -> /usr/src/linux-headers-3.2.0-4-common

I've found a similar bug filled against Debian kernel headers, but it was closed as wontfix: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=521515

Basing on the discussion above, I assume that it should be fixed on the Click side rather than Debian. However I am not enough fluent in configure/kbuild/make things to fix it myself.

[piotrjurkiewicz]

Finally I was able to configure and compile Click kernel module by doing a simple hack:

 cp -r /usr/src/linux-headers-3.2.0-4-common/* /usr/src/linux-headers-3.2.0-4-686-pae/

This is not an elegant solution, but can be helpful if someone has the same problem.

[tbarbette]

With kernel 3.14 (and upper?) this solution is not sufficient anymore and you need to do a "ln -s ../generated/autoconf.h" in "/usr/src/linux-source-3.14/include/linux" or you'll have the following error :

configure: making C++-safe versions of Linux kernel headers (may take a while)
sed: -e expression #1, char 9: unknown option to `s'
checking for C++-includable kernel header files... no
configure: error: 
=========================================

Your Linux kernel header files cause errors when included by a C++ program.

Click modifies the Linux kernel's header files to make them work with
C++, using the program 'linuxmodule/fixincludes.pl'. It looks like
your kernel header files have features that 'linuxmodule/fixincludes.pl'
doesn't know how to fix. You can report this error to us on the Click
mailing list, or, even better, try to fix the error. See the config.log
file for more information on the error.

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