I want (or better need) to debug it using the JTAG transport. So what I did was using this configuration:
source [find interface/stlink-v2.cfg] transport select hla_jtag source [find target/stm32f4x.cfg] reset_config trst_only
The thing is, that it does not connect to the chip at all.
I wired VDD, GND, JNTRST, TMS, TCK, TDI, TDO (accoring to ST UM1075 chapter 4.2). Whenever I try to connect, it finally ends up with claiming the target voltage being too low (see debug log here: http://pastebin.com/raw/yJDvawwJ)
However, connecting JNTRST and TDI to ground and using the SWD transport, it works without problems - also detecting a sufficient voltage (see debug log here: http://pastebin.com/raw/JMuJ1CvS)
BTW: I have perfect 3.3V on the supply pins when I measure the voltage with a multimeter.
When using the ST-Tool under Windows I also cannot connect using JTAG, whereas SWD has no problems.
Any idea what is going wrong here? What configuration am I missing?