Modular Network Stacks

[Gedare Bloom]

Modular Network Stacks

Contents

1. Modular Network Stacks
   1. Mentors
   2. Students
   3. Status
2. Introduction
   1. Prerequisites
   2. Resources
3. Tasks
   1. Legacy Stack
   2. lwIP
   3. libbsd
4. Testing

Mentors

Chris Johns, Sebastian Huber, Pavel Pisa, Joel Sherrill

Students

TBD

Status

Looking for funding/motivated students.

Introduction

The goal of this project is to facilitate use of networking stacks in a more modular fashion.

RTEMS has 3 commonly used networking stacks known as:

• legacy (cpukit/libnetworking): used primarily by established users with networking needs. The most visible of these is the ​EPICS Project.
• libbsd (git.rtems.org/rtems-libbsd.git): state-of-the-art for high-performance networking. It is the recommended stack for new development for systems with sufficient resources to run the stack.
• lwIP: useful for low-resource (usually, RAM) systems to use.

Other networking stacks are also possible to use, but these are the mainly interesting ones.

Prerequisites

• Ability to read/write C programs (pointer-based data structures).
• Ability to debug C programs.
• Ability to read/write Python programs with OOP.
• Ability to compile and run networking applications in *nix and RTEMS.
• Ability to use Wireshark to view network packets.
• Knowledge of one or more assembly languages.
• Knowledge of OSI model.
• Knowledge of hardware and device drivers.

Resources

• Current RTEMS developers.
• ​RTEMS Networking Manual for the legacy stack.
• Packages/LWIP describes some of the prior work with lwIP.
• ​Ragunath's Blog describes his experience using lwIP with RTEMS on the Beaglebone Black.
• ​Beej's Guide to Network Programming is an excellent resource to understand the interface provided by networking stacks.

Tasks

The following are the high-level tasks to accomplish:

Legacy Stack

The legacy stack is loosely coupled to RTEMS. It is built from within rtems.git/cpukit/libnetworking when the --enable-networking option is given during the configure stage of building RTEMS. This subdirectory needs to be factored out of rtems.git and put in its own standalone repository that can be compiled separately from compiling RTEMS. Then, the build process for the legacy network stack should be added to the RSB.

lwIP

lwIP is meant to be compiled and customized with baremetal and RTOS code bases. The main problem with lwIP is that too much customization can make it hard to maintain, and then the port of lwIP bitrots and is no longer usable with RTEMS. Thus, the integration of lwIP with RTEMS needs to be made more seamless and maintainable. The first step in that direction is to revive and fix the RSB recipe for building lwIP, see #3770 for more information. Other problems raised in the [Packages/LWIP] page may also be relevant, and the integration may also require adding any missing bits to newlib as mentioned in #2833.

libbsd

Not much needs to be done here, other than to avoid breaking anything. The libbsd already builds via RSB as a standalone module that can be linked with RTEMS.

Testing

A network-ready target and application should be used for testing. Consult with mentors during the planning phase. The most likely candidate is to use Qemu with a simple networking example.