FreeRTOS/FreeRTOS-Plus/Demo/FreeRTOS_Plus_TCP_Echo_Qemu_mps2

Emulating MPS2 Cortex M3 AN385 on QEMU

Requirements

1. GNU Arm Embedded Toolchain download here
2. qemu-arm-system download here
3. Make (tested on version 3.82)
4. Linux OS (tested on Ubuntu 18.04)

How to download

Navigate to a parent directory of your choice and run the following command

$ git clone https://github.com/FreeRTOS/FreeRTOS.git --recurse-submodules --depth 1

The previous command should create a directory named FreeRTOS

Networking Echo client Demo

To make networking support possible a few steps needs to be done on the machine lets assume the following interfaces using ubuntu 18.04 or Fedora 30 (the interface names on your machine could be different)

l0:         loopback in terface
enp0s3:     ethernet interface
virbr0:     virtual bridge         (to be created)
virbr0-nic: veth virtual interface (to be created)

A few assumptions (your numbers could vary)

Local Host IP address:          192.168.1.81
Local FreeRTOS IP address:      192.168.1.80
Local FreeRTOS Subnet mask:     255.255.255.0
Default Gateway IP address:     192.168.1.254
Default DNS IP address:         192.168.1.254
Echo Server IP address:         192.168.1.204
Echo Server Port:               7
Local FreeRTOS Mac address:     52:54:00:12:34:AD

Building and Running

1. Fill the defines values in FreeRTOSConfig.h with what is equivalent to the above values on your system

#define configIP_ADDR0          192
#define configIP_ADDR1          168
#define configIP_ADDR2          1
#define configIP_ADDR3          80

#define configNET_MASK0         255
#define configNET_MASK1         255
#define configNET_MASK2         255
#define configNET_MASK3         0

#define configGATEWAY_ADDR0     192
#define configGATEWAY_ADDR1     168
#define configGATEWAY_ADDR2     1
#define configGATEWAY_ADDR3     254

#define configDNS_SERVER_ADDR0  192
#define configDNS_SERVER_ADDR1  168
#define configDNS_SERVER_ADDR2  1
#define configDNS_SERVER_ADDR3  254

#define configMAC_ADDR0         0x52
#define configMAC_ADDR1         0x54
#define configMAC_ADDR2         0x00
#define configMAC_ADDR3         0x12
#define configMAC_ADDR4         0x34
#define configMAC_ADDR5         0xAD

#define configECHO_SERVER_ADDR0 192
#define configECHO_SERVER_ADDR1 168
#define configECHO_SERVER_ADDR2 1
#define configECHO_SERVER_ADDR3 204

2. Build your software

$ make

options: DEBUG=1 to build with -O0 and debugging symbols

3. On the remote machine (ip 192.168.1.204)

$ sudo nc -l 7

4. Turn off the firewall if running On RedHat/Fedora system (tested Fedora 30) run:

sudo systemctl status firewalld
sudo systemctl stop firewalld

On Ubuntu run:

$ sudo ufw disable
$ sudo ufw status

5. Setup the local machine Run the following commands replacing the values and interface names that conform to your system

sudo ip link add virbr0 type bridge
sudo ip tuntap add dev virbr0-nic mode tap

sudo ip addr add 192.168.1.81/24 dev virbr0

sudo brctl addif virbr0 enp0s3
sudo brctl addif virbr0 virbr0-nic

sudo ip link set virbr0 up
sudo ip link set virbr0-nic up

sudo ip route add default via 192.168.1.254 dev virbr0

6. Run the demo

$ sudo qemu-system-arm -machine mps2-an385 -cpu cortex-m3 
          -kernel ./build/RTOSDemo.axf \
          -netdev tap,id=mynet0,ifname=virbr0-nic,script=no \
          -net nic,macaddr=52:54:00:12:34:AD,model=lan9118,netdev=mynet0 \
          -object filter-dump,id=tap_dump,netdev=mynet0,file=/tmp/qemu_tap_dump\
          -display gtk -m 16M  -nographic -serial stdio \
          -monitor null -semihosting -semihosting-config enable=on,target=native 

Replace the value of macaddr=52:54:00:12:34:AD with your own value from

configMAC_ADDR0 through  configMAC_ADDR5

7. Expectations On the remote machine you should expect to see something similar to the following:

$ sudo nc -l 7
Password:
TxRx message number
0FGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~0123456789:;<=> ?
@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~0123456789:;<=>?
@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~0123456789:;<=>?
@ABCDEFGHIJKLM

How to start debugging

1. gdb

Append the -s and -S switches to the previous command (qemu-system-arm)
-s: allow gdb to be attached to the process remotely at port 1234
-S: start the program in the paused state

run: (make sure you build the debug version)

$ arm-none-eabi-gdb -q ./build/RTOSDemo.axf

(gdb) target remote :1234
(gdb) break main
(gdb) c

2. tcpdump To monitor packets received to qemu running the qemu command (qemu-system-arm) shown above will create a network packet dump that you could inspect with

$ sudo tcpdump -r /tmp/qemu_tap_dump  | less