Rubis Technologies has announced the initial release of SRLinux, which the company claims represents the first embeddable real-time Linux kit for MIPS processors. SRLinux stands for “Super Real-time Linux” and consists of two distinct software packages: real-time Linux executables, which include binaries and (some) sources; and a set of cross-development tools that are used to configure and modify the… executables for deployment in a particular target system. SRLinux currently supports a number of MIPS processors made by IDT and NEC, including: IDT's R3000/4000 series, RC32334 32-bit series, and RC574/545 64-bit series; and NEC's VR41XX series, VR10000, and (soon) NEC VR12000.

Target system executables

The SRLinux executables include binary files for a target BIOS (RBIOS), the Linux kernel and its associated modules, and an RTLinux-like real-time add-on component (MUTRIX). Memory requirements for these components are (typically):

• RBIOS: 64 KB
  
• MUTRIX: 24 KB (R3000); 128 KB (IDT RC574/575 & NEC VR series)
  
• Linux: 120 KB, minimum (kernel with serial I/O); 560 KB, typical (without X)

A complete system can be loaded from 1MB of Flash storage memory and can run in 2MB of system RAM.

The primary purpose of RBIOS is to perform hardware initialization, load the MUTRIX real-time extensions module, and then bring in the Linux kernel. RBIOS is the only piece of software that needs to be resident within a bootstrap ROM or Flash chip on the target system.

MUTRIX is meant to serve as a buffer between the system and all real-time events, and is designed to keep running in the event of a Linux OS malfunction. Like RTLinux or RTAI, MUTRIX intercepts I/O events and passes control to the Linux kernel only after pending real-time tasks have been serviced. MUTRIX also provides support for hot-swapping peripheral cards in CompactPCI systems. According to Rubis Technologies, MUTRIX offers context switch and worst case latency times of 2 MIPS instructions and its operation can be interrupt driven, event driven, or both (interrupts can be nested). MUTRIX, which is completely independent of Linux code, is written in assembler and must be adapted to each target processor.

The Linux kernel and associated modules, optimized by Rubis Technologies for MIPS processors, are based on Linux kernel 2.2.16 and are supplied in source form. RBIOS and MUTRIX, on the other hand, are proprietary software and are distributed pre-compiled. They are configured using a cross development toolkit, also provided by Rubis Technologies.

Cross development toolkit

The cross development toolkit is used to configure, compile, and load the system executables into the target system. The tools run on x86 PCs under any distribution of Linux and include GNU tools such as cross Gcc, cross Gcc+, cross Objc, cross GAS, cross GLD, and cross GDB. Several unique tools created by Rubis Technology are also provided: CRBIOS configures the RBIOS boot loader; MUTRIXT configures and monitors the MUTRIX real-time module; and RUBLINUX is the Linux source files management utility.

Availability and cost

A production version (IV1.2.2) is currently available for use on supported IDT processors. A Beta version (NV1.1.0) for NEC processors is also ready. Clustering features are in development, an alpha version of which is available for IDT processors.

Source code for the modified Linux kernel and associated modules (which are GPL) will soon be available for download from the Rubis Technologies website. RBIOS and MUTRIX, being proprietary software, will normally be provided in binary format only; however, their sources will be available for a fee, governed by a nondisclosure agreement and other restrictions. There are no royalties required to use the executables within products. Pricing for the toolkit, which is required in order to configure, adapt, and use RBIOS and MUTRIX on a specific target system, ranges from $5000 to $8500 (depending on number and type of processors required).

Rubis Technologies is located in Guerard, FRANCE (near Paris). The company, whose target markets are the telecom and automotive industries, is currently a supplier of process control equipment to auto manufacturers Peugeot, Citroen, Renault, GM (DeCarbon), DBenz, and AUDI. Further information is only available via email, at present. A website will be online soon.

 
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