So, I take a look on the HOWTO : Upgrading the kernel from firnsy present on this forum

I followed all steps

for cloop, I use apt-get install and make_kpkg modules_image to build cloop.ko.
The test with modprobe is fine

for unionfs, I use the 1.0.14 like in the howto
in the step #make unionfs2.6 I have a warning :

Code:
__rcuref_hash undefined!
in the step #make install it stop with an error

Code:
uuid_t undeclared
this error is mentioned in the INSTALL file of the 1.1.1 version :

Code:
if you get an error like this :
unionimap.h:9:23 uuid/uuid.h: No such file or directory
Followed, by more parse errors, then you need to make sure you have e2fsprogs-devel installed (or your distribution's equivalent)
Under Debian, it is e2fslibs-dev and I have this package

however this error, the unionfs.ko is present in the directory. Without the -g debug option, I get an unionfs.ko of 2.0MB

To place the new kernel and modules under the minirt.gz I must delete scsi directory.

And, when I boot from the iso with qemu I have the same error ....

ERROR: CANNOT UNITE READ-ONLY MEDIA AND INITIAL RAMDISK!