[yocto] Building an atom-pc image

[Jack]

Hi,

I looked at this page https://www.yoctoproject.org/download/intel%C2%AE-
atom%E2%84%A2-based-pcs-and-devices-atom-pc . I downloaded atom-pc-dylan-
9.0.0.tar.bz2 and ran bitbake core-image-minimal. When building process 
finished, I didn't give core-image-minimal-atom-pc with .hddimg. While some 
other extension files like .ext3 and .cpio were built. How can I build an 
image minimal with .hddimg extension?

Thanks.