Today I was able to successfully debug code on the STM32F0Discovery Board using the OpenOCD-0.6.0-devGDB Server in an eclipse environment under windows 7 (64-bit). I was also able to use the openOCD-0.6.0-dev for programming and erasing the stm32F051C8 chip on board. The advantage of the openOCD GDB Server is that its free, open source and hackable, unlike the closed Atollic GDBServer. openOCD is also much more flexible and can be used to debug/program, practically all ARM based chips. The openOCD GDB Server output is shown in Figure 1.
The catch to using OpenOCD with the STM32F0Discovery board is that it requires a LibUSB driver. The Atollic GDBServer and the STLINK Utility both use a WinUSB based driver. This basically means that in order to use openOCD, you will have to uninstall the WinUSB driver and install the LibUSB one. At which point you will be unable to use STLink Utility and the Atollic GDB Server until you reinstall the WinUSB driver back again. Luckily flashing and erasing the chip as well as debugging with openOCD is pretty simple so the STLINK utility will not be needed. I will be releasing a second openOCD-based debug tutorial once a final version of the openOCD-0.6.0 is released...hopefully soon. In the meantime, if you want to play around with the openOCD 0.6.0-dev (under development) version please check out Freddie Chopin's website linked here.