Jazelle DBX对Android是无用的

Jazelle DBX: Direct Bytecode eXecution

ARMprocessors historically support two instruction sets: the ARM instruction set,in which all

instructionsare 32-bits long, and the Thumb® instruction set which compresses themost-commonly used

instructionsinto a 16-bit format. The Thumb instruction set typically offers 35-40% codecompression

comparedto ARM code for a small performance reduction. The instruction set supportsprocedure calls

betweenARM and Thumb code, so application programmers typically choose at compile timewhether

partsof the application should be compiled for performance or code density.

The ARM Jazelle technology extends this concept by adding a thirdinstruction set –Java Byte Code– to

the capability of the processor - along with this, we addinstruction set support for entering (and exiting)

Java applications.

 

Android Dalvik uses its own Byte Code but notJava Byte Code, so Jazelle DBX isuseless to Android.