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AR# 16633

3.1 EDK - There appears to be a bug in the ppc/mb compiler?? (The "volatile" keyword is possibly required in the declaration)


General Description:

A bug appears to be present in the ppc/mb compiler.


In some cases, your coding style may affect the compiler results. The "volatile" keyword is an important concept in embedded programming.

Most compilers optimize the code by assuming that a value stays in the memory unless the program changes it. General compilers feature this optimization for better performance. In embedded system applications, this may cause a problem in the shared-data code and I/O access. Make sure that you use the "volatile" keyword in the variable declaration (the "volatile" keyword is part of the C standard.) This keyword specifies to the compiler that the microprocessor must read the value from the memory location (or memory-mapped location) every time it is referenced.

AR# 16633
Date Created 09/03/2007
Last Updated 12/15/2012
Status Active
Type General Article