Remote GDB with Gem5 - remote-debugging

Question

gem5 has built-in support for GDB’s remote debugger interface. I want to debug a very tiny code using remote gdb with Gem5 (in se mode).
As we can see from the below image, the program I want to debug (just for testing) has a scanf statement to read a value from user. However, when I type cont in the gdb (on host machine) the program (at simulated machine in Gem5) does not stop at this statement to enter a value. Even I set a breakpoint at this statement, also, the program at gem5 does not stop (to enable me to enter the value of int variable) and finishes its work.
As we can see from the gem5's output... the value of int variable is randomly assigned.
what is really the issue here? is it because scanf statement? or I wrong in somethings?!
How to work with remote gdb in tandem with Gem5?
Both the host and the simulated machine are x86 (no need for cross-gdb)
Regardless of scanf, I have a very simple program that contains three print instructions. I put a breakpoint at the third print instruction, both programs at host and Gem5 stop at this point. when I cont the program at host, it continues its work normally, but at gem5 the program gets stuck and does not continue.
Cross-gdb
The above work was conducted using x86 as a host machine with x86-Gem5. Now I want to test cross-gdb. In my host machine I installed all cross-tools required (gcc, g++ and gdb) to work with ARM simulated machine in Gem5.
From the host machine I started the gdb and typed the following commands:
gdb-multiarch
file arm_test // a sample code compiled using arm-gcc cross compiler
set architecture arm
set b main
target remote localhost:7000
c
when I hit enter after typing c (cont) the program at Gem5 does not stop at main (as I set a breakpoint there) and it finishes its work, prints hello world and exits.
At the Gem5 I saw a warn message says: warn: Invalid breakpoint length
Updated
I have used the following GDB flags to figure out and inspect the data being transmitted to the (host gdb) from Gem5 and vice versa.
--debug-flag=GDBSend,GDBRecv,GDBMisc
As we can see from the image below
when I set a breakpoint at a specific location in the code (say function call) that is located at address offset (1031e) ... a bunch of information is send to Gem5 as it's clear from the image:
0: system.remote_gdb: recv: m1031e,2 // receive
0: system.remote_gdb: send: fff7 // send what ???
0: system.remote_gdb: recv: Z0,1031e,3 // receive
I hope someone help me and explain what does "Z0,1031e,3" really mean? I know that the gem5 has received data from (host gdb) which tell it to set a breakpoint at instruction located at offset 1031e. BUT WHAT does the number three mean here?
Because I think it is the main cause of the problem; when I hit cont at (host gdb) the program at gem5 side never stops and finishes its work with the mentioned warn message: warn: Invalid breakpoint length
WHAT is the valid length? and how to adjust it?
if I set a bp at another location (say at a place of printf instruction), also I got an error.
0: system.remote_gdb: set software breakpoint, addr=0x1030a, len=2
warn: Invalid breakpoint length
Any help or suggestions please!
Gem5 branch: Stable
Config file: se.py
thanks