dist/tools/openocd: start debug-server in background and wait

[fabian18]

Contribution description

When the target debug-server is called from a remote it is not so convenient to exit it properly, because Ctrl+C is cached by make itself. This terminates the script but the server keeps running, consequently a second invocation of the debug-server fails. A fix for this would be to start the server in the background, save the PID in a file and wait for the openocd process. This PR makes the openocd server shutdown when Ctrl+D is pressed or anything else can read the PID file and kill the server.

Testing procedure

BOARD=same54-xpro make flash debug-server with set -x

### Starting GDB Server ###
+ test_config
+ '[' '!' -f /home/fabian.huessler@ml-pa.loc/RIOT/boards/same54-xpro/dist/openocd.cfg ']'
++ mktemp -t openocd_pid.XXXXXXXXXX
+ OCD_PIDFILE=/tmp/openocd_pid.GX9T0mZT2N
+ trap 'cleanup /tmp/openocd_pid.GX9T0mZT2N' EXIT
+ read -r line
+ sh -c 'openocd             -c '\''source [find interface/cmsis-dap.cfg]'\'' -c '\''transport select swd'\''             -f '\''/home/fabian.huessler@ml-pa.loc/RIOT/boards/same54-xpro/dist/openocd.cfg'\''                          -c '\''bindto localhost'\''             -c '\''tcl_port 6333'\''             -c '\''telnet_port 4444'\''             -c '\''gdb_port 3333'\''             -c '\''init'\''                          -c '\''targets'\''             -c '\''halt'\'' &             echo $! > /tmp/openocd_pid.GX9T0mZT2N ;             wait $(cat /tmp/openocd_pid.GX9T0mZT2N)'
Open On-Chip Debugger 0.12.0-rc3-00999-gfcb40f49b (2023-05-12-10:54)
Licensed under GNU GPL v2
For bug reports, read
        http://openocd.org/doc/doxygen/bugs.html
swd
Info : CMSIS-DAP: SWD supported
Info : CMSIS-DAP: FW Version = 03.25.01B6
Info : CMSIS-DAP: Serial# = ATML2748101800010083
Info : CMSIS-DAP: Interface Initialised (SWD)
Info : SWCLK/TCK = 1 SWDIO/TMS = 1 TDI = 1 TDO = 1 nTRST = 0 nRESET = 1
Info : CMSIS-DAP: Interface ready
Info : clock speed 2000 kHz
Info : SWD DPIDR 0x2ba01477
Info : [atsame5.cpu] Cortex-M4 r0p1 processor detected
Info : [atsame5.cpu] target has 6 breakpoints, 4 watchpoints
Info : starting gdb server for atsame5.cpu on 3333
Info : Listening on port 3333 for gdb connections
    TargetName         Type       Endian TapName            State       
--  ------------------ ---------- ------ ------------------ ------------
 0* atsame5.cpu        cortex_m   little atsame5.cpu        running

[atsame5.cpu] halted due to debug-request, current mode: Handler PendSV
xPSR: 0x8100000e pc: 0x0000972e msp: 0x20000190
Info : Listening on port 6333 for tcl connections
Info : Listening on port 4444 for telnet connections

+ echo 'Exit with Ctrl+D'
Exit with Ctrl+D
+ read -r line

+ echo 'Exit with Ctrl+D'
Exit with Ctrl+D
+ read -r line
+ cleanup /tmp/openocd_pid.GX9T0mZT2N
++ cat /tmp/openocd_pid.GX9T0mZT2N
+ OCD_PID=154902
+ kill 154902
+ rm -f /tmp/openocd_pid.GX9T0mZT2N
shutdown command invoked
+ exit 0
Terminated

Issues/PRs references

[riot-ci]

Murdock results

✔️ PASSED

1b93025 dist/tools/openocd: start debug-server in background and wait

Success	Failures	Total	Runtime
1	0	1	56s

Artifacts

• Documentation preview

[benpicco]

Why is the background wait needed?
Does it keep the script (and trap) alive for the cleanup?

[fabian18]

I just tested it without the ampersand in L437 and I think what happens then is that the shell waits for the openocd process to finish, while it is running obviously. So the script does not get to the while read until something on the remote side kills openocd

[benpicco]

bors merge

[bors]

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• Murdock
• static-tests
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