I am working on a building a new distro based on the metadata provided by yocto/poky for a custom ARM product for which we are using our own custom kernel. We are currently working off of poky git tag 1.4_M4.final. The problem I am seeing at the moment is that the udev init script will attempt to mount /dev using 'tmpfs' if 'devtmpfs' is not available when in fact (according to someone I spoke with on #udev) udev-182 requires the use of devtmpfs. I understand that Yocto typically expects to build its own kernel with a particular configuration that probably already includes devtmpfs, but it seems like the init script out to fail with a useful message anyway if devtmpfs is not available.
http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=b378cb75609d7beade67321036788ea0845dd624