In case you face problems with launching GDB: Then I have a quick solution (well: workaround): kill the GDB server and or client process. The problem can show up in many way, but in general gdb is stuck or does not respond:
GDB stuck?
But it could be an error message like this too:
Error in services launch sequence Starting J-Link GDB Server timed out.
In many cases it helps to repower the debug probe and/or target board (see “Debugging Failure: Check List and Hints“). Other than that, what helps most of the time for me is to kill the gdb client and/or gdb server tasks.
GDB Client
What happens if I press ‘debug’ in Eclipse is: Eclipse launches the gdb client. For ARM this is arm-none-eabi-gdb and in the case of Kinetis Design Studio v3.0.0 it is located here:
C:\Freescale\KDS_3.0.0\toolchain\bin\arm-none-eabi-gdb.exe
You can identify the gdb client easily in the Windows task manager:
arm-none-eabi-gdb.exe
Where to find the gdb client is configured in the Eclipse launch configuration:
GDB Client Setup
The executable is specified with variables like ${cross_prefix}:
${cross_prefix}gdb${cross_suffix}
You can inspect the variables with the menu Window > Preferences > C/C++ > Build > Build Variables (make sure you enable ‘Show system variables’):
Eclipse System Build Variables
Segger J-Link GDB Server
Both gdb client and gdb server are launched from Eclipse. The gdb client then communicates with the gdb server. Which is JLinkGDBServerCL.exe in case of Segger J-Link:
JLink GDB Server
That Segger gdb server executable can be found in Kinetis Design Studio v3.0.0 here:
C:\Freescale\KDS_3.0.0\segger\JLinkGDBServerCL.exe
This is configured in the Eclipse debug configuration:
Calling J-Link Server
OpenOCD GDB Server
OpenOCD works the same way:
OpenOCD gdb server
The OpenOCD server binary is located here:
C:\Freescale\KDS_3.0.0\openocd\bin\openocd.exe
P&E GDB Server
Both Segger J-Link and OpenOCD server used with Eclipse are executables outside of the Eclipse plugins folder. The path to the P&E GDB server binary is not configurable in the P&E debug panel and is present inside the Eclipse plugins folder. In the case of Windows and Kinetis Design Studio v3.0.0 it is located here:
C:\Freescale\KDS_3.0.0\eclipse\plugins\com.pemicro.debug.gdbjtag.pne_2.0.8.201504092111\win32\pegdbserver_console.exe\
Having the server inside the Eclipse plugins folder makes it possible that I can update it using the usual Eclipse updates.
The P&E GDB server can be easily identified in the process list as pegdbserver_console:
P&E GDB Server
Summary
So if something went wrong, then usually what works is to terminate/kill gdb server and client in the Windows task manager:
- GDB Client: arm-none-eabi-gdb
- Segger J-Link GDB Server: JLinkGDBServerCL
- P&E Multilink GDB Server: pegdbserver_console
- OpenCD GDB Server: openocd
In a similar way, things work as well on Linux or Mac OS.
Happy Killing 🙂
MCU on Eclipse 
Yeah, P&E GDB Server is notorious in Linux, I kill it all the time, just go to terminal and run ‘top’, get the pid and ‘kill pid’
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Hi Erich,
Have you ever come across an example which implements GDB debugging in a custom programming environment? For example, I’m developing my own IDE as part of a visual programming package and I want to be able to start and debug the source created by my tool.
I’m at the stage now where I can compile and program the micro-controller through a Segger J-Link however I’d like to take the next step and get debugging going.
Hope this makes sense!
Regards,
Kevin
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Hi Kevin,
GDB comes with the GDB MI (Machine Interface) which you could use as communication between your IDE and the GDB debugger: https://sourceware.org/gdb/onlinedocs/gdb/GDB_002fMI.html
I hope this helps,
Erich
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Hi Erich,
Thanks for your reply, I’ll investigate the GDB MI.
On a slight side note, do you think this could be something that you could work with: kck.st/1S0HyUp
Kind regards,
Kevin
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Hi Kevin,
if it is a NXP/Freescale ARM M4: yes!
Erich
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Hi Erich,
Its an NXP/FSL K22
Kind regards,
Kevin
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Hi Kevin,
I’m in 🙂
Erich
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Hi Erich,
That’s fabulous, thank you for your support. Should you have any questions, please don’t hesitate to ask. Likewise, if you know anyone who may also be interested, please get them on board.
Kind regards,
Kevin
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Hi Kevin,
just did 🙂
Erich
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Fantastic, thank you ever so much! 🙂
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Thank you for an excellent article – well done and thank you
i am trying these similare examples and have run in to a problem:
both on Linux and Window 11 using Eclipse and Segger J-LINK
—————————————————————————-
Error in final launch sequence
Failed to execute MI command:
-target-select remote localhost:2331
Error message from debugger back end:
Truncated register 16 in remote ‘g’ packet
Failed to execute MI command:
-target-select remote localhost:2331
Error message from debugger back end:
Truncated register 16 in remote ‘g’ packet
Truncated register 16 in remote ‘g’ packet
SEGGER J-Link GDB Server V8.10a Command Line Version
JLinkARM.dll V8.10a (DLL compiled Oct 2 2024 14:18:10)
Command line: -if swd -device RP2040_M0_0 -endian little -speed auto -port 2331 -swoport 2332 -telnetport 2333 -vd -ir -localhostonly 1 -log /home/walter/Jbug.log -singlerun -strict -timeout 0 -nogui
—–GDB Server start settings—–
GDBInit file: none
GDB Server Listening port: 2331
SWO raw output listening port: 2332
Terminal I/O port: 2333
Accept remote connection: localhost only
Generate logfile: off
Verify download: on
Init regs on start: on
Silent mode: off
Single run mode: on
Target connection timeout: 0 ms
——J-Link related settings——
J-Link Host interface: USB
J-Link script: none
J-Link settings file: none
——Target related settings——
Target device: RP2040_M0_0
Target device parameters: none
Target interface: SWD
Target interface speed: auto
Target endian: little
Connecting to J-Link…
J-Link is connected.
Firmware: J-Link V11 compiled Oct 1 2024 13:26:26
Hardware: V11.00
S/N: XXXXXXXXX
Feature(s): RDI, FlashBP, FlashDL, JFlash, GDB
Checking target voltage…
Target voltage: 3.32 V
Listening on TCP/IP port 2331
Connecting to target…
Initializing CPU registers…Connected to target
Waiting for GDB connection…Connected to 127.0.0.1
GDB client (conn. 12) requested target.xml from GDB Server
Reading common registers: Read register ‘r0’ (4 bytes) from hardware: 0x00000000
Read register ‘r1’ (4 bytes) from hardware: 0x00000000
Read register ‘r2’ (4 bytes) from hardware: 0x00000000
Read register ‘r3’ (4 bytes) from hardware: 0x00000000
Read register ‘r4’ (4 bytes) from hardware: 0x00000000
Read register ‘r5’ (4 bytes) from hardware: 0x00000000
Read register ‘r6’ (4 bytes) from hardware: 0x00000000
Read register ‘r7’ (4 bytes) from hardware: 0x00000000
Read register ‘r8’ (4 bytes) from hardware: 0x00000000
Read register ‘r9’ (4 bytes) from hardware: 0x00000000
Read register ‘r10’ (4 bytes) from hardware: 0x00000000
Read register ‘r11’ (4 bytes) from hardware: 0x00000000
Read register ‘r12’ (4 bytes) from hardware: 0x00000000
Read register ‘sp’ (4 bytes) from hardware: 0x00000000
Read register ‘lr’ (4 bytes) from hardware: 0x00000000
Read register ‘pc’ (4 bytes) from hardware: 0x00000000
Read register ‘xpsr’ (4 bytes) from hardware: 0x00000001
GDB closed TCP/IP connection (Socket 12)
Restoring target state and closing J-Link connection…
Shutting down…
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From the output, it looks like your debug connection (cable) is not good enough, maybe a contact problem.
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