Debugging: Unable to halt execution using arm gdb

[weinand]

From @am1ko on April 26, 2017 19:21

• VSCode Version: 1.11.2 (1.11.2)
• OS Version: MacOS Sierra 10.12.3

Steps to Reproduce:

1. Setup launch.json to use arm-none-eabi-gdb for debugging a c program on an embedded target (see attached launch.txt)
2. Set one breakpoint to beginning of main
3. Start debug session
4. Breakpoint in main fires. Press "play" button to continue
5. Try to halt the target by pressing "pause"

The result is that nothing happens. Any attempt to use the debug console results is
"Unable to perform this action because the process is running."

The way to halt the execution when using command line arm-none-eabi-gdb is to press ctrl-c (SIGINT?). Could this option be added to vscode debugger config?

launch.txt

Copied from original issue: microsoft/vscode#25467

[weinand]

From @timurey on June 18, 2017 18:30

Have the same issue.

[pieandcakes]

@am1ko @timurey If you set "stopAtEntry" to true does it stop? Did you compile with the -g flag?

[am1ko]

I just tried "stopAtEntry" and it seems to have no effect whatsoever.
I am compiling with -g flag. Here are the compiler flags I use:

arm-none-eabi-gcc -x assembler-with-cpp -c -mcpu=cortex-m7 -mthumb -mfpu=fpv5-sp-d16 -mfloat-abi=hard -O0 -Wall -fdata-sections -ffunction-sections -g -gdwarf-2

For me, execution halts on a breakpoint at the beginning of main regardless of "stopAtEntry" value. I can add multiple breakpoints while the target is halted and they all work. It's just that I cannot halt with the pause button or add new breakpoints anymore while it's running. I would need a way to send ctrl+c to the arm-none-eabi-gdb process.

[pieandcakes]

@am1ko Can you enable "logging" : { "trace": true, "traceResponse": true, "engineLogging": true } and retry your scenario and send me the log?

I have seen issues in GDB where it won't allow us to set breakpoints while running in MI mode.

[am1ko]

launch copy.json.txt

[am1ko]

debug_log.txt

[am1ko]

@pieandcakes logs attached

I tried to halt and add breakpoints from vscode when recording the log but I see no log entries written at those times.

The breakpoint you see being hit is something that I trigger by controlling the ui of the program being debugged.

[timurey]

My gcc options: -mcpu=cortex-m3 -mthumb -fmessage-length=0 -ffunction-sections -fdata-sections -std=c11 -Og -g3 -flto
launch.json.txt
And I have absolutely same reaction on trying to halt or add breakpoint while programs is running.

But if I connect to openocd via telnet, I can halting program by halt command.

[pieandcakes]

@timurey @am1ko Can either of you try and run -exec -gdb-set target-async off in the Debug Console when you are stopped and see if the breakpoints are responsive? I'm hearing that some of versions of gdb are not handling this correctly.

[timurey]

Result:

-exec -gdb-set target-async off
1: (8106) <-1018-gdb-set target-async off
1: (8106) ->1018^error,msg="Cannot change this setting while the inferior is running."
1: (8106) ->(gdb)
1: (8106) 1018: elapsed time 0
result-class: error
msg: Cannot change this setting while the inferior is running.

in telnet console:

> set target-async off
off

But still can't halt running or add breakpoint.

[am1ko]

vscode version 1.15.1 (1.15.1)
arm-none-eabi-gcc version 6.3.1 20170620

After updating vscode and gcc I now see debug output when trying to break. Still does not work though

C pause: {"threadId":57005}
R: {"success":true,"message":null,"request_seq":23,"command":"pause","body":null,"running":false,"refs":null,"seq":0,"type":"response"}

[am1ko]

@pieandcakes
Tried your suggestion. Same result as @timurey

C evaluate: {"expression":"-exec -gdb-set target-async off","frameId":1000,"context":"repl"}
1: (34420) <-1092-gdb-set target-async off
1: (34421) ->1092^error,msg="Cannot change this setting while the inferior is running."
1: (34421) ->(gdb)
1: (34421) 1092: elapsed time 0
E output: {"category":"stdout","output":"result-class: error\r\nmsg: Cannot change this setting while the inferior is running.\r\n\n","data":null,"type":"output"}
result-class: error
msg: Cannot change this setting while the inferior is running.

[am1ko]

If I do
"setupCommands": [
{
"text": "set target-async off"
},

I can break the execution successfully form bash by sending SIGINT to the gdb process
kill -2 31276

vscode pause button still doesn't work.