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Atomic Read Modify Write
The x86 instruction set has the possibility to prefix some instructions with a LOCK prefix:
- bit test and modify
- increment, decrement, not,add,sub,and,or
These will cause the processor to assert the LOCK# bus signal for the duration of the read and write.
The processor automatically asserts the LOCK# signal during execution of an XCHG , during a task switch, while reading a segment descriptor
Author: Roberto Innocente