Hello, just a quick note about this bug report. The real problem was that the model was not listed in libdebian-installer/src/system/subarch-powerpc-linux.c, and thus partman-prep was not loaded for it, which means that the prep partition, and more importantly the debconf value for the boot partition was not set, and thus yaboot-installer failed to work as expected. libdebian-installer 0.36 will fix this issue. Friendly, Sven Luther