In Application Output pane we can observe next text (bare-metal remote debugging is used):
{code}
Debugging starts
questing target halt and executing a soft rese
rget halted in ARM state due to debug-request, current mode: Superviso
sr: 0x600000d3 pc: 0x0000000
U: disabled, D-Cache: disabled, I-Cache: disable
apter speed: 1000 kH
ading done
{code}

Some of the given string from the Debugger log console:
{code}
>&"monitor soft_reset_halt\n"
>&"requesting target halt and executing a soft reset\n"
>@"requesting target halt and executing a soft reset\n"
 questing target halt and executing a soft rese
...
>&"monitor echo \"Loading done.\"\n"
>&"Loading done.\n"
>@"Loading done.\n"
 ading done
>79^done
{code}

Problem in gdbengine.cpp in GdbEngine::handleRespone() in "case '@'". I add debug output and capture next result
{code}
Buff: "@\"requesting target halt and executing a soft reset\\n\"" , data: "requesting target halt and executing a soft reset\n" , msg: "questing target halt and executing a soft rese"
Buff: "@\"target halted in ARM state due to debug-request, current mode: Supervisor\\n\"" , data: "target halted in ARM state due to debug-request, current mode: Supervisor\n" , msg: "rget halted in ARM state due to debug-request, current mode: Superviso"
Buff: "@\"cpsr: 0x600000d3 pc: 0x00000000\\n\"" , data: "cpsr: 0x600000d3 pc: 0x00000000\n" , msg: "sr: 0x600000d3 pc: 0x0000000"
Buff: "@\"MMU: disabled, D-Cache: disabled, I-Cache: disabled\\n\"" , data: "MMU: disabled, D-Cache: disabled, I-Cache: disabled\n" , msg: "U: disabled, D-Cache: disabled, I-Cache: disable"
Buff: "@\"adapter speed: 1000 kHz\\n\"" , data: "adapter speed: 1000 kHz\n" , msg: "apter speed: 1000 kH"
{code}

Where:

• Buff - handleResponse() arg
• data - string result of GdbMi::parseCString(from, to) call
• msg - result string

More analysis:
{code}
Input Buff: "@\"requesting target halt and executing a soft reset\\n\""
From-to data: "requesting target halt and executing a soft reset\n"
Result msg: "questing target halt and executing a soft rese"
{code}

Observation:
1. Two first signs drops
2. Two last signs drops

Seem that given switch case was not changed when from/to iterators logic was reworked. Currently
from already points to the valid place and mid(2) is not required. We also want to keep last symbol,
but must trunk new-line. So fix must be simple:
{code}
QString msg = data.left(data.size() - 1);
{code}