`make term` no longer works with JLinkExe v6.94

[bartcerneels]

While starting to use RTT as the stdio for an STM32L496VG based board make term was not working. It still worked with JLink v6.92.

Steps to reproduce the issue

I've configured a board to use JLink RTT in Makefile.include:

JLINK_DEVICE = STM32L496VG

RIOT_TERMINAL = jlink
include $(RIOTMAKE)/tools/serial.inc.mk

include $(RIOTMAKE)/tools/jlink.inc.mk

Then run make term

Expected results

$ JLINK=/opt/SEGGER/JLink_Linux_V692_x86_64/JLinkExe make term
/home/bart/Bond/Code/iot_firmware/RIOT/dist/tools/jlink/jlink.sh term-rtt 
### Starting RTT terminal ###
Twisted not available, please install it if you want to use pyterm's JSON capabilities
2021-02-16 11:36:56,254 # Host name for TCP connection is missing, defaulting to "localhost"
2021-02-16 11:36:56,254 # Connect to localhost:19021
Welcome to pyterm!
Type '/exit' to exit.
2021-02-16 11:36:57,258 # SEGGER J-Link V6.92 - Real time terminal output
2021-02-16 11:36:57,258 # SEGGER J-Link Ultra V4.0, SN=504504798
2021-02-16 11:36:57,258 # Process: JLinkExe
2021-02-16 11:36:57,259 # main(): This is RIOT! (Version: 2021.01-devel-2-g46a9e-HEAD)

Actual results

$ JLINK=/opt/SEGGER/JLink_V694d/JLinkExe make term
/home/bart/Bond/Code/iot_firmware/RIOT/dist/tools/jlink/jlink.sh term-rtt 
### Starting RTT terminal ###
Twisted not available, please install it if you want to use pyterm's JSON capabilities
2021-02-16 11:09:05,532 # Host name for TCP connection is missing, defaulting to "localhost"
2021-02-16 11:09:05,532 # Connect to localhost:19021
2021-02-16 11:09:05,534 # Something went wrong connecting to localhost:19021
Killing 68643
/home/bart/Bond/Code/iot_firmware/RIOT/dist/tools/jlink/jlink.sh: 281: kill: No such process

Versions

Our clone of RIOT is not based on the latest and has 2 fixes related to UART and building on windows. These should not affect the jlink script. I've checked out the current master (ce0d589) and it has the same problem.

Operating System Environment
----------------------------
         Operating System: "KDE neon" "5.20"
                   Kernel: Linux 5.4.0-59-generic x86_64 x86_64
             System shell: /usr/bin/dash (probably dash)
             make's shell: /usr/bin/dash (probably dash)

Installed compiler toolchains
-----------------------------
               native gcc: gcc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0
        arm-none-eabi-gcc: arm-none-eabi-gcc (GNU Arm Embedded Toolchain 9-2020-q2-update) 9.3.1 20200408 (release)
                  avr-gcc: missing
         mips-mti-elf-gcc: missing
           msp430-elf-gcc: missing
       riscv-none-elf-gcc: missing
  riscv64-unknown-elf-gcc: missing
     riscv-none-embed-gcc: missing
     xtensa-esp32-elf-gcc: missing
   xtensa-esp8266-elf-gcc: missing
                    clang: missing

Installed compiler libs
-----------------------
     arm-none-eabi-newlib: "3.3.0"
      mips-mti-elf-newlib: missing
        msp430-elf-newlib: missing
    riscv-none-elf-newlib: missing
riscv64-unknown-elf-newlib: missing
  riscv-none-embed-newlib: missing
  xtensa-esp32-elf-newlib: missing
xtensa-esp8266-elf-newlib: missing
                 avr-libc: missing (missing)

Installed development tools
---------------------------
                   ccache: missing
                    cmake: cmake version 3.16.3
                 cppcheck: missing
                  doxygen: 1.8.17
                      git: git version 2.25.1
                     make: GNU Make 4.2.1
                  openocd: Open On-Chip Debugger 0.10.0+dev-g4e85dcf4 (2020-11-24-10:58)
                   python: Python 3.8.5
                  python2: Python 2.7.18
                  python3: Python 3.8.5
                   flake8: error: /usr/bin/python3: No module named flake8
               coccinelle: missing

[haukepetersen]

I can confirm this issue: just updated from JLink V6.80d to V7.20a, and for me make term using jlink and stdio_rtt also stopped to work, same behavior as stated above.

I am unsure what is causing this, but I am hopeful to find the cause of this soon, as this is annoying me a bit :-)

@bartcerneels I do have a temporary workaround:

• run JLinkExe stand-alone in a terminal window
• connect manually to your board, in my case (using nrf52) I do this by typing connect -> nrf52 -> s -> 2000
• in a second terminal, invoke make term as usual, Now it should succeed.

[immesys]

Hey, I am unable to work on this, sorry. I've left the lab I used to work in and don't have any of the equipment needed to work on this anymore.

[haukepetersen]

I have been starring at this all evening now and can't figure this out. When running JLinkExe manually as background job on my Linux host, as in

JLinkExe -nogui 1 -exitonerror 1 -device 'nrf52' -speed '1000' -if 'SWD' -jtagconf -1,-1 -commandfile '/home/hauke/dev/riot/RIOT/dist/tools/jlink/term.seg' >/dev/null 2>&1 &

it will run jlink as expected.
But when passing that exact same command as a string argument to my dash shell

sh -c "JLinkExe -nogui 1 -exitonerror 1 -device 'nrf52' -speed '1000' -if 'SWD' -jtagconf -1,-1 -commandfile '/home/hauke/dev/riot/RIOT/dist/tools/jlink/term.seg' >/dev/null 2>&1 &"

jlink will not continue to run in the background, but will be closed instantly. I was able to see this behavior for any jlink version of V6.94 and higher, while it works perfectly fine for V6.92 and below. As far as I can tell, there is no hint in the jlink release nodes that would point to any changes in jlink that could be causing this... So for now I really can't tell, somebody else with an enlightenment?