I am also trying to debug a stm32f4 discovery board.
at least could get the st-link gdbserver to run via DEBUG.
But there is still a problem with the read socket, which ends up in closing the st-link gdb server.

iam using the tooolchain from sourcery and the st-link gdb server from attolic.

Here is my logwith the error at 0.509ms:
[0.229] STM32_AppReset(): NVIC_DFSR_REG = 0x00000009
[0.231] STM32_AppReset(): NVIC_CFGFSR_REG = 0x00000000
[0.233] STM32_AppReset(): XPSR = 0x41000000
[0.233] STM32_InitDevice(): ST_LINK Major version =2 Jtag version =17
[0.233] STM32_InitDevice(): ST_LINK VID=1155 PID=14152
[0.234] STM32_InitDevice(): ST_LINK device status: HALT_MODE
[0.240] stm32_reset_hw_wtchpt_module(): Hardware watchpoint supported by the target
[0.248] create_stm32_flash_device(): FuncEntry
[0.249] create_stm32_flash_device(): STM32 device: id =10016413
[0.250] create_stm32_flash_device(): STM32 device: Flash size =1024
[0.250] create_stm32_flash_device(): FuncExit
[0.250] read_f2_option_bytes(): FuncEntry
[0.255] read_f2_option_bytes(): FuncExit
[0.255] main(): Start Logging
[0.260] Socket_WaitForTrueStudioConnection(): Waiting for TrueSTUDIO client to connect on port 61234 …
[0.509] Socket_WaitForTrueStudioConnection(): TrueSTUDIO client connected.
[0.509] Socket_WaitForTrueStudioConnection(): Receive buffer size set to 65536 bytes.
[0.509] Socket_Write(): Tx: #724b$

[0.509] Socket_Read(): Rx: +$qSupported:qRelocInsn+#9a
[0.609] main(): Error while waiting for debugger connection.

@bazis wrote:

As discussed per email, this is the limitation of the TrueSTUDIO GDB server. Using a GDB server that is not restricted to TrueSTUDIO is the solution.

Yep, as i told you, you either can use the gsb-server from atollic in version 1.3.0 or the texane/stlink uitl.
However it works fine now