Description of problem: Currently the environmental variable for pxe boot file load address is "pxe_addr_r", should be renamed "pxefile_addr_r" on at least the pandaboard and beaglebone.
uboot-tools-2014.10-4.fc21 has been submitted as an update for Fedora 21. https://admin.fedoraproject.org/updates/uboot-tools-2014.10-4.fc21
Package uboot-tools-2014.10-4.fc21: * should fix your issue, * was pushed to the Fedora 21 testing repository, * should be available at your local mirror within two days. Update it with: # su -c 'yum update --enablerepo=updates-testing uboot-tools-2014.10-4.fc21' as soon as you are able to. Please go to the following url: https://admin.fedoraproject.org/updates/FEDORA-2014-13809/uboot-tools-2014.10-4.fc21 then log in and leave karma (feedback).
uboot-tools-2014.10-4.fc21 has been pushed to the Fedora 21 stable repository. If problems still persist, please make note of it in this bug report.