This variable attribute enables you to specify the absolute address of a variable.
The variable is placed in its own section, and the section containing the variable is given an appropriate type by the compiler:
Read-only variables are placed in a section of type RO.
Initialized read-write variables are placed in a section of type RW.
Variables explicitly initialized to zero are placed in:
A section of type ZI in RVCT 4.0 and later.
A section of type RW (not ZI) in RVCT 3.1 and earlier. Such variables are not candidates for the ZI-to-RW optimization of the compiler.
Uninitialized variables are placed in a section of type ZI.
Note
This variable attribute is not supported by GNU compilers.
SyntaxThe linker is not always able to place sections produced by
the at variable attribute.
The compiler faults use of the at attribute
when it is used on declarations with incomplete types.
The linker gives an error message if it is not possible to place a section at a specified address.
const int x1 __attribute__((at(0x10000))) = 10; /* RO */ int x2 __attribute__((at(0x12000))) = 10; /* RW */ int x3 __attribute__((at(0x14000))) = 0; /* RVCT 3.1 and earlier: RW. * RVCT 4.0 and later: ZI. */ int x4 __attribute__((at(0x16000))); /* ZI */
Using __at sections to place sections at a specific address in Using the Linker.
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