ARM Jazelle® technology for acceleration of execution environments provides the ARM Connected Community with high quality, class leading solutions for the ARM architecture that offer the optimum combination of high performance, low power and low cost.  

Jazelle technology is a combined hardware and software solution from ARM. ARM Jazelle technology software is a full featured multi-tasking Java Virtual Machine (JVM), highly optimized to take advantage of Jazelle technology architecture extensions available in many ARM processor cores.

ARM Jazelle technology hardware extensions are available from over 50 ARM silicon partners. ARM Jazelle technology software is available pre-integrated into a complete Java platform from a range of ARM software partners.

ARM Jazelle software includes technology to enable Jazelle hardware in any existing JVM and Java platform. It also includes a full featured multi-tasking VM (MVM) already integrated into many Java platforms from leading handset vendors and Java platform software vendors. By utilizing the underlying Jazelle technology architecture extensions, the ARM MVM software solution delivers high performance applications and games, fast start-up and application switching with a very low memory and power budget.


High Performance

  • Jazelle DBX is widely used to deliver very high performance Java in mobile handsets and other consumer devices without affecting memory consumption, battery life or user experience.
  • Jazelle RCT can reduce significantly the code bloat associated with AOT and JIT compilation, making AOT technology viable on mass-market devices.
  • Additionally Jazelle RCT can also be used to support execution environments beyond Java, such as Microsoft .NET Compact Framework, Python and others.

Excellent User Experience

  • The impact of application pauses during execution or slow start-times, due to the overhead of JIT compilation can be significant on a user - a 1-second pause in a game would render the device unusable.
  • Jazelle DBX can be used to improve user experience and start time and reduce memory overheads when using a JIT, by reducing the amount of runtime compilation or replacing the JIT altogether.
  • Jazelle RCT can be used to allow AOT compilation to be used more extensively and can also be combined with JIT technology on very high frequency platforms, where start-time and smoothness issues lessen

Low system cost & Wide Industry Adoption

  • Jazelle DBX and Jazelle RCT solutions are cache and memory efficient, maintaining low power while keeping system costs low through efficient memory and cache usage.
  • Jazelle DBX is a robust and proven solution, integrated with Java platforms from leading third party software vendors and incorporated into solutions from most of the leading handset vendors worldwide as well as non-mobile consumer devices such as BluRay disc players.
  • Jazelle DBX is simple to integrate, requires no time-consuming compiler tuning for different platforms and applications. Major Java platform vendors support it.
  • Jazelle RCT provides an excellent target for any run-time compilation technology, including JIT and AOT for .NET MSIL, Python and Perl as well as Java. ARM is working with leading software providers to enable solutions ready for market with Jazelle RCT.

Delivering Choice

Through the development of extensions to the ARM architecture, our software products and industry partnerships, ARM enables our partners to deliver the very best solutions for execution environments.

For example, for Java platforms, developers have the choice to:

  • Implement Jazelle DBX alone, for a resource constrained device where the available memory for a compiler or the JIT compile time overhead mean AOT or JIT are not suitable.
  • On mid-range platforms that support Jazelle DBX and Jazelle RCT, utilize both, with Jazelle DBX for interpreted Java execution Jazelle RCT for selective AOT on a platform sensitive to user experience issues, such as start-time.
  • Use Jazelle RCT for JIT and AOT, plus Jazelle DBX to improve start time and user experience issues with the JIT on a platform sensitive to user experience issues, such as start-time.
  • On high-end platforms, use Jazelle RCT alone with JIT and AOT where, because the platform may be running at frequencies in the order of a GHz, issues such as start-time are less.

ARM Jazelle DBX (Direct Bytecode eXecution) technology for direct bytecode execution of JavaTM delivers an unparalleled combination of Java performance and the world's leading 32-bit embedded RISC architecture - giving platform developers the freedom to run Java applications alongside established OS, middleware and application code on a single processor.

ARM Jazelle RCT (Runtime Compilation Target) technology supports efficient ahead-of-time (AOT) and just-in-time (JIT) compilation with Java and other execution environments.  

There are a number of ways for a virtual machine to execute bytecode:

Direct interpretation, where each bytecode is translated to machine code in software, offers the most memory efficient solution. The vast majority of J2ME Java solutions in the market today use bytecode interpretation. Without hardware acceleration, direct interpretation may not have the performance required to run the more compelling applications.

Just in Time (JIT) or Dynamic Adaptive Compilation (DAC) compilation, where code is first interpreted as above, and profiled to identify the most frequently executed code. These code segments are then compiled to native ARM code. The time taken to profile and compile code at run-time can result in excessive start-up times and jerkiness, resulting in a bad user experience. Code expansion or “bloat” is typically 4 to 8x the original bytecode, increasing memory and system cost and power consumption. Typical JIT and DAC compiler solutions are highly complex pieces of software and require significant effort to tune for the target platform, increasing cost of ownership.

Ahead of Time (AOT) compilation, occurs where the application is compiled, either before download (at the server), on installation (during device manufacture) or while downloading the application for the first time. AOT compilation can deliver good performance, but can also be extremely costly in terms of memory code bloat, so selective AOT compilation can work in combination with JIT or interpreter techniques

ARM offers a range of solutions and an innovative technology roadmap to solve the performance and feature requirements of J2ME Java platforms, with products for CDC and CLDC.

Developed by an ARM team of unparalleled experience in creating the most highly optimized JVM solutions for the ARM Jazelle technology platforms, Jazelle software solutions provide extremely high performance and incredible user experience for a wide range of consumer devices, from mobile phones to BluRay DVD players.

The Jazelle Java Technology Enabling Kit (JTEK) has been licensed since 2002 to enable JVMs to take full advantage of Jazelle DBX technology-enabled processors offering high performance in up to 8x less RAM compared to software only approaches.

ARM has worked with major handset and independent software vendors, continually improving performance of its Jazelle JTEK software since its launch, doubling the performance of version 3 versus version 2 of Jazelle JTEK through software alone, while minimizing memory usage.

Partner requests for a multi-tasking Java platform required ARM to re-architect the JVM to be a Multi-tasking Virtual Machine (MVM). Working with leading industry Partners and handset vendors, ARM has developed a highly optimized MVM implementation - achieving high performance, fast response and switching, smooth consistent behavior and a very small memory footprint.

Jazelle MobileVM

The ARM MVM solution forms the basis of the ARM Jazelle MobileVM software.

Jazelle MobileVM is a complete JVM, engineered to provide high performance multi-tasking in a very small memory footprint. ARM continues to invest in and build major new features to enhance the Java platform, including a runtime bytecode optimizer capable of improving performance by a further 40%, and a novel approach to on-target debug that allows fast deployment and extremely simple customizability. That results in faster time to market for developers and an ability for handset vendors and network operators to customize on-target debug for their developer communities.


ARM Jazelle software is available from a range of Software Partners. Please talk to us about your requirements and we will be happy to help.

Wide Adoption

ARM Jazelle software products are licensed and shipping today in hundreds of millions of mobile handsets and other consumer devices from major OEMs worldwide. Many leading mobile network operators recommend or mandate Jazelle technology.



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