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Symptom


Debian, Suse, and other distributions with recent 2.6.29 and higher kernels, package their kernel headers in a new architecture-specific manner, which breaks compatibility with earlier established methods of building modules for kernels.

Prior to CDP 4, 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.

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-2.6.32-5-common-xen' for kernel headers Found headers in 'linux-headers-2.6.32-5-common-xen' 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 ~~~~~~

 

 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 the common/architecture specific symlinks for the kernel headers in 2.6.29 and higher, which has broken parts of the kernel module building process, including the R1Soft CDP Agent 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

 

 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:

cd /usr/src/ rsync -avz /usr/src/linux-headers-2.6.32-5-xen-amd64/ r1build/ rsync -avz /usr/src/linux-headers-2.6.32-5-common-xen/ r1build/


Now, point the r1soft-cki utility to use your temporary directory, with the following flags added to the command:

CDP2

# /usr/bin/r1soft-cki --get-module --kernel-dir /usr/src/r1build

CDP3 

# /usr/bin/r1soft-setup --get-module --kernel-dir /usr/src/r1build




After a successful build, you can delete the temporary directory, restart the agent, and enjoy Continuous Data Protection!

rm -r /usr/src/r1build

CDP2

 /etc/init.d/buagent restart

CDP3

/etc/init.d/cdp-agent restart

Labels:
linux_3 linux_3 Delete
kernel_3 kernel_3 Delete
debian debian Delete
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