Compiling a Module on Debian with Linux Kernel 2.6.29 and Higher

Version 4 by John Donnelly
on May 09, 2012 14:20.

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on May 09, 2012 14:21.

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which breaks compatibility with earlier established methods of building modules for kernels.

Prior to CDP 4 release, attempting to build kernel modules on these linux distributions can prove unsuccessful.

This is the excerpted output from one attempt. In our example here, we use r1soft-cki, but this applies for r1soft-setup in CDP as well.

...

{code}
root@box~# /usr/bin/r1soft-cki
Checking for binary module
..
No binary module found
Gathering kernel information
Gathering kernel information complete.
Creating kernel headers package
Checking '/usr/src/linux-headers-2.6.30-1-common' for kernel headers
Found headers in '/usr/src/linux-headers-2.6.30-1-common'
Compressing...
uploading kernel package 100% 3863KB 3.8MB/s 00:01
Starting module build...
............................gathering required information...
sending request for kernel module...
kernel module installer failed. (0):
chroot chroot make
make[1]: Entering directory `/'
~~~~~~
make: Entering an unknown directory
make: *** /usr/src/linux-headers-2.6.30-1-common: No such file or directory. Stop.
make: Leaving an unknown directory
make[4]: *** [all] Error 2
~~~~~~
{code}
{kb-cause}
This issue is known to affect Debian, Suse, and other distros using separate architecture-specific module directories in their header packages.
Thanks to Chris at Interspire.com for working closely with us to discover a resolution.

The Debian developers have removed their common/architecture specific symlinks for the kernel headers in 2.6.29 and higher,
and in the process, have broken a whole heap of kernel module building, including the R1Soft CDPAgent module
(refer to here: [http://bugs.debian.org/cgi-bin/bugrepaort.cgi?bug=521515])

Basically, there are now two kernel module directories, both of which contain necessary files:

drwxr-xr-x 4 root root 4096 2010-01-20 05:43 linux-headers-2.6.32-trunk-amd64
drwxr-xr-x 4 root root 4096 2010-01-20 05:47 linux-headers-2.6.32-trunk-common
{kb-resolution}
Copying the contents of these two directories into a temporary directory, with the proper makefile chosen,
will allow the r1soft-cki process to compile a module successfully.
{code}
cd /usr/src/
rsync -avz linux-headers-2.6.32-3-amd64/ /usr/src/r1build/
rsync -avz linux-headers-2.6.32-3-common/ /usr/src/r1build/
{code}
Now, point the r1soft-cki utility to use your temporary directory, with the following flags added to the command.

*CDP2*
{code}
# /usr/bin/r1soft-cki --get-module --kernel-dir /usr/src/r1build
{code}
*CDP3 *
{code}
# /usr/bin/r1soft-setup --get-module --kernel-dir /usr/src/r1build
{code}
After a successful build, you can delete the temporary directory, start the agent, and enjoy Continuous Data Protection\!
{code}
rm -r /usr/src/r1build
buagentctl start
{code}
{kb-related-articles}