For your info to finish off: as suggested by Robert Nelson, I upgraded to
v3.8.13-bone28. After spending time to get back to where I used to be in
bone20, I can now compile and load the overlay as expected:
>sudo sh -c "dtc -@ -O dtb -o BB-BONE-PRU-00A0.dtbo BB-BONE-PRU-00A0.dts"
>sudo sh -c "ec
Update, recompiled with different name, and then overlay load appears to
work
/lib/firmware\> sudo sh -c "dtc -@ -O dtb -o cape-bone-pru-00A0.dtbo
BB-BONE-PRU-00A0.dts"
[19392.918341] bone-capemgr bone_capemgr.9: part_number 'BB-BONE-PRU',
version 'N/A'
[19392.918537] bone-capemgr bone_capemgr.9
