STM32的RAM的绝对地址定位，以及初始化不为0

MDK帮助文档里面写的还是比较清楚：

__attribute__((at(address))) variable attribute

ARM Compiler toolchain v5.02 for µVision Compiler Reference

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__attribute__((at(address))) variable attribute

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.

Syntax

__attribute__((at(address)))

where:

address

is the desired address of the variable.

Restrictions

The 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.

Errors

The linker gives an error message if it is not possible to place a section at a specified address.

Examples

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 */

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关于RAM初始化不为0

Noinit selects areas that should be excluded from zero initialization。

NoInit

Specifies areas that should be excluded from zero initialization.

NOINIT

Indicates that the data section is uninitialized, or initialized to zero. It contains only space reservation directives SPACE or DCB, DCD, DCDU, DCQ, DCQU, DCW, or DCWU with initialized values of zero. You can decide at link time whether an area is uninitialized or zero initialized.

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NOINIT的资料网上非常少。看样子大家用的不多啊。

MDK的target界面有个选项NOINIT ，看样子只能靠这个设置了。还是比较靠谱。