If you run bitbake package-index when using the RPM backend it is not unlikely it will fail with the following: ERROR: There are no packages in /path/to/tmp/deploy/rpm! Looking at the log you can tell it is not looking at the correct list of package architectures, and the reason for this is that package_update_index_rpm() uses MULTILIB_PREFIX_LIST which is only set (separately) when populate_sdk_rpm or rootfs_rpm are inherited, which is not the case for the package-index recipe. Even if it does not fail it will not be indexing all of the package architectures. Fixing this properly will require some refactoring. In the meantime I have a stopgap fix that I will be sending for 1.5.
Fix merged to master: http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=2f64fae60b3f61a2c45dc9e5314d2d16b1e64605 I've entered bug 5286 to cover the refactoring, so I'll mark this one as resolved.
'bitbake package-index' works after the fix. Verified in: poky master:2f64fae60b3f61a2c45dc9e5314d2d16b1e64605