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Host Emulator

Mike edited this page Jun 13, 2019 · 6 revisions

The latest versions of Sming allow most of components of the library and the sample applications to be compiled on a Linux/Windows host system and be tested before uploading them to the microcontroller.

If you want to try it we have interactive tutorial that can be run directly from your browser.

Requirements

Modern Linux distribution

Most popular modern distributions should be fine. At the moment we develop only with Ubuntu 16.04 and 18.04.

C/C++ 32 bit compiler and libraries

If your OS is 64 bit then you should install also 32 bit C/C++ compiler and libraries. Under Ubuntu those can be installed using the command below

sudo apt-get install gcc-multilib g++-multilib

CMake 3.8 or newer

For the compilation of LWIP CMake version 3.8 or newer is required. In order to get newer Cmake version under Ubuntu 16.04 one should execute the commands below:

cd /tmp
wget https://github.com/Kitware/CMake/releases/download/v3.14.4/cmake-3.14.4-Linux-x86_64.sh 
sudo mkdir /opt/cmake
sudo sh cmake-3.14.4-Linux-x86_64.sh --prefix=/opt/cmake
sudo mv /usr/bin/cmake /usr/bin/cmake.orig
sudo ln -s /opt/cmake/bin/cmake /usr/bin/cmake

Compilation

Environment variables

The following environmental variable have to be set to use Host as the desired architecture.

export SMING_ARCH=Host

Debug Build

If you plan to use a debugger make sure to set the following environmental variables before compiling the code:

export ENABLE_GDB=1  
export ENABLE_LWIPDEBUG=1  # <!-- this will compile also LWIP with debug symbols

Initial Clean-up

Make sure that you are working on a clean source code tree. The following commands may help:

cd $SMING_HOME
make dist-clean

Sample compilation

Compile a sample as usual using the following command sequence:

cd $SMING_HOME/../samples/Basic_Blink
make 

Adapting existing code

You may need to modify your existing applications to work with the emulator. Architecture-specific code should be moved into separate code modules. Code that is specific to the ESP8266 may be conditionally compiled using #ifdef ARCH_ESP8266. Similarly, you can check if the code is compiled for the emulator using #ifdef ARCH_HOST.

Running on the host

Once the sample is compiled you can run it on the host using the command below:

make flash

This will create a file system and run the code.

If you would like to run the code only then use the following command:

make run

Networking

Support is provided via TAP network interface (a virtual network layer operating at the ethernet frame level). A TAP interface must be created first, and requires root privilege:

sudo ip tuntap add dev tap0 mode tap user `whoami`
sudo ip a a dev tap0 192.168.13.1/24
sudo ifconfig tap0 up

# The following lines are needed if you plan to access Internet
sudo sysctl net.ipv4.ip_forward=1
sudo sysctl net.ipv6.conf.default.forwarding=1
sudo sysctl net.ipv6.conf.all.forwarding=1

export INTERNET_IF=wlan0 # <!--- Make sure to replace wlan0 with the network interface connected to Internet

sudo iptables -t nat -A POSTROUTING -o $INTERNET_IF -j MASQUERADE
sudo iptables -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
sudo iptables -A FORWARD -i tap0 -o $INTERNET_IF -j ACCEPT

This creates the tap0 interface. The emulator will automatically select the first tap interface found. To override this, use the --ifname option.

Troubleshooting

Issue 1: fatal error: sys/cdefs.h: No such file or directory

Make sure to install the 32bit version of the GNU C and C++ compiler, development package and libraries.

Issue 2: fatal error: bits/c++config.h: No such file or directory

Make sure to install the 32bit version of the GNU C and C++ compiler, development package and libraries.

Further reading

Make sure to read the Host architecture Readme.md file.

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