Generic Abstraction Layers for Linux VEE Ports

Overview

This project contains all the Abstraction Layers implementation to run the VEE on a Linux system.

It also contains a cmake project with differents sets of configuration (toolchains, features).

This Abstraction Layer requires a GNU GCC 32 bit toolchain as well as a few listed C libraries, see Requirements

Supported Features

This Abstraction Layer is compliant with Architecture 8.x and the following Packs:

Pack Name	Version
DEVICE	1.2.0
ECOM-NETWORK	1.0.0
FS	6.0.4
NET	11.1.0
UI	14.0.2

Architecture

The Multi-Sandbox Application download implementation is based on malloc/free in RAM, so without reboot persistence.

Device Pack

The Device UID is based on the Ethernet HWAddr.

Networking Pack

Both IPv4 a IPv6 are supported.

SSL supports TLSv1, TLSv1.1, TLSv1.2, DTLS1.2.

Security algorithms:

Cipher: AES-128-CBC, AES-192-CBC, AES-256-CBC, DES-CBC
RSA Cipher: RSA/ECB/PKCS1Padding, RSA/ECB/OAEPWithSHA-1AndMGF1Padding, RSA/ECB/OAEPWithSHA-256AndMGF1Padding
Digest: MD5, SHA-1, SHA-256, SHA-512
Key generation: EC, RSA
HMAC: SHA-256
Signature: SHA256withRSA, SHA256withECDSA

UI Pack

This Abstraction Layer implements the display on either the Linux kernel Frame Buffer or Direct Rendering Manager (libdrm).

Usage

This project has 2 configuration steps.

First you add this Abstraction Layer into a Linux VEE Port project.

Then you customize the features for your VEE Port requirements.

How to Use this Abstraction Layer in a Linux VEE Port

A typical Linux VEE Port can use this Abstraction Layer as its BSP to build and run the VEE.

See MicroEJ documentation about BSP connection.

The following folder structure can be used:

a VEE Port configuration project containing the board specific configurations (see details below)
a VEE Port Abstraction Layer (the current repository, named Linux-abstractionlayer), with all the necessary C Abstraction Layers and scripts

It should look like this:

Linux-configuration/
├── bsp
│   ├── bsp.properties
│   └── scripts
│       ├── project_options.cmake
│       ├── set_project_env.sh
│       └── toolchain.cmake
├── configuration.xml
├── module.ivy
└── override.module.ant
Linux-abstractionlayer/
└── projects
    └── microej
        └── ...

The VEE Port configuration project uses variables to locate the Linux-abstractionlayer folder. For example in Linux-configuration/bsp/bsp.properties:

microejapp.relative.dir=projects/microej/platform/lib
microejlib.relative.dir=projects/microej/platform/lib
microejinc.relative.dir=projects/microej/platform/inc
microejscript.relative.dir=projects/microej/scripts
root.dir=${project.parent.dir}/Linux-abstractionlayer

The VEE Port configuration project imports the module.properties file. For example in Linux-configuration/override.module.ant:

        <property file="${override.module.dir}/../Linux-abstractionlayer/module.properties"/>

The VEE Port configuration project imports the configuration.xml file. For example in Linux-configuration/configuration.xml:

        <!-- Import BSP Configuration script -->
        <import file="${project.parent.dir}/Linux-abstractionlayer/configuration.xml"/>

How to Customize the VEE Port

Build & Run Scripts

In the directory project/microej/scripts/ are scripts that can be used to build and flash the executable.
The .bat and .sh scripts are meant to run in a Windows and Linux environment respectively.

The build* scripts are used to compile and link the Abstraction Layers with a MicroEJ Application to produce a MicroEJ executable (application.out) that can be run on a Linux device.

The build* scripts work out of the box, assuming the toolchain is configured properly, see :ref:Plaftorm configuration section
The run* scripts are used to send and execute a MicroEJ executable (application.out) on a device, over SSH.

The environment variables can be defined globally by the user or in the set_local_env* scripts. When the .bat (.sh) scripts are executed, the set_local_env.bat (set_local_env.sh) script is executed if it exists. Create and configure these files to customize the environment locally.

Host Configuration

Target SSH Configuration

See set_local_env.sh. This is where you can configure the SSH_HOSTNAME variable.

This address is then used to deploy the executable on the target automatically.

WSL Configuration (if using WSL for Windows)

See set_local_env.bat. The default setting is Ubuntu, but if you have several WSL distributions it could be different.

You can verify your WSL distribution name with the commande wsl --list in Windows terminal and then set the correct value in this script:

IF [%WSL_DISTRIBUTION_NAME%] == [] (
  SET WSL_DISTRIBUTION_NAME=Ubuntu
)

VEE Port Configuration

At build time, the VEE Port configuration project will install the 3 following files into the project/microej/scripts/ folder:

set_project_env.sh

This script is used to setup environment variables for compilation (such as the path to the Compiler and/or Yocto SDK).

toolchain.cmake

This is a cmake configuration file purely dedicated to the toolchain configuration.

project_options.cmake

This is a cmake configuration file dedicated to the Abstraction Layers configuration.

set_project_env.sh

This general script will be sourced before calling the cmake build. It is used to export environment variables (ex: $CC, $CFLAGS) for cross compilation.

Here is an example when building with a Yocto SDK:

#!/bin/bash
#
# BASH
#
# Copyright 2024 MicroEJ Corp. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be found with this software.

# Toolchain settings:
# Application SDK installation path (e.g. /usr/local/oecore-x86_64)
if [ -z $YOCTO_SDK_INSTALL ]; then
YOCTO_SDK_INSTALL=/usr/local/oecore-x86_64
fi
if [ -z $YOCTO_SDK_ENV_SCRIPT ]; then
 YOCTO_SDK_INSTALL=environment-setup-armv7at2hf-neon-vfpv4-oemllib32-linux-gnueabi
fi

if [ ! -d "$YOCTO_SDK_INSTALL" ]; then
echo ""
echo "ERROR: YOCTO_SDK_INSTALL="$YOCTO_SDK_INSTALL" is not a valid path."
echo "Please verify set_project_env.sh"
echo ""
exit -1
fi

. "$YOCTO_SDK_INSTALL/$YOCTO_SDK_ENV_SCRIPT"

toolchain.cmake

This file is used to setup the cmake toolchain

Using Yocto SDK

When building with a Yocto SDK, the toolchain configuration will mostly come from the Yocto SDK environment script sourced in set_project_env.sh. A few additional settings are necessary like setting the sysroot, see below:

# Copyright 2024 MicroEJ Corp. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be found with this software.
#
# Toolchain settings
#

set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_PROCESSOR arm)

# set(CMAKE_C_COMPILER ${CC})

# fetch SYSROOT variable if set by Yocto SDK environment script
set(CMAKE_SYSROOT $ENV{SDKTARGETSYSROOT})

set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)

Using a Standalone Toolchain

Here is how to cross compile for i686 GCC on Ubuntu, see the CMAKE_C_COMPILER variable below:

# Copyright 2024 MicroEJ Corp. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be found with this software.
#
# Toolchain settings
#

set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_PROCESSOR X86)

set(CMAKE_C_COMPILER i686-linux-gnu-gcc)

# fetch SYSROOT variable if set by Yocto SDK environment script
# set(CMAKE_SYSROOT $ENV{SDKTARGETSYSROOT})

set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)

project_options.cmake

This is where all the generic Abstraction Layers configuration takes place.

How to Add Your Own Abstraction Layer

With the following syntax, you can specify the source of external code:

#
# Abstraction Layer external source
#
# set(ABSTRACTION_LAYER_EXTERNAL ../../../Linux-abstractionlayer-imx93)
# When specifying an out-of-tree source a binary directory must be explicitly specified
# here we will install the output files in a subdirectory of CMAKE_CURRENT_BINARY_DIR
# add_subdirectory(${ABSTRACTION_LAYER_EXTERNAL} Linux-abstractionlayer-imx93)

How to Set Custom CFLAGS Options

Here is an example when building a 32bit executable for a 64bit target:

#
# CFLAGS
#
# generate 32bit code, see https://gcc.gnu.org/onlinedocs/gcc/x86-Options.html
set(CFLAGS ${CFLAGS} -m32)
# Prevent floating point comparison issues with 32bit code. Known GCC issue, see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=323#c109
set(CFLAGS ${CFLAGS} -msse -mfpmath=sse)

How to Enable/Disable Abstraction Layers

The list of options can be found in the options.cmake file.

This file lists all the different options, and sets a default value with the option(<variable> "<help_text>" [value]) syntax.

# Select which Abstraction Layer to build
option(BUILD_CORE         "Build Core Abstraction Layer"                   ON)
option(BUILD_ECOM_NETWORK "Build Embedded COMmunication Abstraction Layer" ON)
option(BUILD_FS           "Build File System Abstraction Layer"            ON)
option(BUILD_KF           "Build Kernel Feature Abstraction Layer"         ON)
option(BUILD_NET          "Build Network Abstraction Layer"                ON)
option(BUILD_SECURITY     "Build Security Abstraction Layer"               ON)
option(BUILD_SSL          "Build SSL Abstraction Layer"                    ON)
option(BUILD_UI           "Build UI Abstraction Layer"                     ON)
option(BUILD_UTIL         "Build Util Abstraction Layer"                   ON)
option(BUILD_VALIDATION   "Build validation utilities"                     OFF)

Examples:

If your VEE Port doesn't have the FS Foundation Library, you can disable BUILD_FS.
BUILD_VALIDATION is only used to validate the core architecture.

To disable a feature, simply add the following line in the project_options.cmake file of your VEE Port project:

set(BUILD_XXX         "Build XXX Abstraction Layer"                   OFF)

Abstraction Layers Specific Configurations

# Set specific features
if (BUILD_UI)
  option(BUILD_UI_TOUCHSCREEN "Build UI Touchscreen feature" ON)
  option(BUILD_UI_FRAMERATE "Build UI Framerate debug feature" OFF)
  option(BUILD_UI_FBDEV "Build UI Framebuffer device support" ON)
  option(BUILD_UI_DRM "Build UI DRM Framebuffer support" OFF)
endif()

if (BUILD_NET)
  option(ENABLE_NET_AF_IPV4_SUPPORT "IPv4 support" ON)
  option(ENABLE_NET_AF_IPV6_SUPPORT "IPv6 support" OFF)
endif()

BUILD_UI_TOUCHSCREEN is based on tslib API (https://github.com/libts/tslib).
BUILD_UI_FBDEV and BUILD_UI_DRM are mutually exclusive.
- If Linux only supports the legacy frame buffer (/dev/fb0), select BUILD_UI_FBDEV
- Otherwise, if Linux supports DRM, select BUILD_UI_DRM.
- If you don't have a display, just disable BUILD_UI.

Debug and Advanced Features

# Debug features
option(ADVANCED_TRACE "Enable MJVM Advanced trace" OFF)

ADVANCED_TRACE is used for Advanced Event Tracing

Requirements

This Abstraction Layer implementation requires a GNU compiler for 32-bit Linux architecture.

The following libraries must be installed in the sysroot:

libc.so
libssl.so
libcrypto.so
libdrm.so (optional, for DRM displays only)
libts.so (optional)

As an example with Yocto, on a ARMv7 chipset, the following configuration can be done:

echo -e "require conf/multilib.conf" >>  ./conf/local.conf
echo -e "MULTILIBS = \"multilib:lib32\"" >>  ./conf/local.conf
echo -e "DEFAULTTUNE:virtclass-multilib-lib32 = \"armv7athf-neon\"" >>  ./conf/local.conf
echo -e "IMAGE_INSTALL:append = \" lib32-glibc lib32-libgcc lib32-libstdc++\"" >> ./conf/local.conf 
echo -e "IMAGE_INSTALL:append = \" lib32-libssl lib32-libdrm lib32-tslib\"" >> ./conf/local.conf

Dependencies

All dependencies are retrieved transitively by MicroEJ Module Manager.

Source

N/A

Restrictions

None.

Name		Name	Last commit message	Last commit date
Latest commit History 5 Commits
projects/microej		projects/microej
.gh-copyright.template		.gh-copyright.template
.gitignore		.gitignore
.gitmodules		.gitmodules
.project		.project
CHANGELOG.md		CHANGELOG.md
LICENSE.txt		LICENSE.txt
README.md		README.md
configuration.xml		configuration.xml
module.ivy		module.ivy
module.properties		module.properties

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Generic Abstraction Layers for Linux VEE Ports

Overview

Supported Features

Architecture

Device Pack

Networking Pack

UI Pack

Usage

How to Use this Abstraction Layer in a Linux VEE Port

How to Customize the VEE Port

Build & Run Scripts

Host Configuration

Target SSH Configuration

WSL Configuration (if using WSL for Windows)

VEE Port Configuration

set_project_env.sh

toolchain.cmake

Using Yocto SDK

Using a Standalone Toolchain

project_options.cmake

How to Add Your Own Abstraction Layer

How to Set Custom CFLAGS Options

How to Enable/Disable Abstraction Layers

Abstraction Layers Specific Configurations

Debug and Advanced Features

Requirements

Dependencies

Source

Restrictions

About

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MicroEJ/AbstractionLayer-Linux

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Repository files navigation

Generic Abstraction Layers for Linux VEE Ports

Overview

Supported Features

Architecture

Device Pack

Networking Pack

UI Pack

Usage

How to Use this Abstraction Layer in a Linux VEE Port

How to Customize the VEE Port

Build & Run Scripts

Host Configuration

Target SSH Configuration

WSL Configuration (if using WSL for Windows)

VEE Port Configuration

set_project_env.sh

toolchain.cmake

Using Yocto SDK

Using a Standalone Toolchain

project_options.cmake

How to Add Your Own Abstraction Layer

How to Set Custom CFLAGS Options

How to Enable/Disable Abstraction Layers

Abstraction Layers Specific Configurations

Debug and Advanced Features

Requirements

Dependencies

Source

Restrictions

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