I just did a git pull today to this commit:

commit a01aef5d2f96c334d048f43f0d3573a1152b37ca
Merge: c728876 21a4d96
Author: Peter Maydell <peter.maydell@linaro.org>
Date:   Fri Jun 24 11:00:15 2016 +0100

When I tried to run qemu-system-ppc with and without the -bios option, all I see is a empty black window. Switching consoles yields a Guest hasn't initialized the display yet message. Are you having better luck or is this a known issue?