Building for BB-xM with Yocto

[Sascha Young]

Has anyone been able to build a current image for the Beagleboard-xM using Yocto?  

The current process I'm following has been 

git clone git://git.yoctoproject.org/poky

source poky/oe-init-build-ebv ./build

export MACHINE=beagleboard

bitbake nano 

(the last command was to test that i could build anything for the beagleboard) 

but i get the following error:

ERROR:  OE-core's config sanity checker detected a potential misconfiguration.

    Either fix the cause of this error or at your own risk disable the checker (see sanity.conf).

    Following is the list of potential problems / advisories:

    MACHINE=beagleboard is invalid. Please set a valid MACHINE in your local.conf, environment or other configuration file.

Summary: There was 1 ERROR message shown, returning a non-zero exit code.

Does anyone know what I need to do or can anyone point me to current instructions for building a minimal image for bb-xM

Much appreciated, 

Alex Young