如何将变量放置在内存中的给定绝对地址处(使用 GCC) [英] How to place a variable at a given absolute address in memory (with GCC)

问题描述

RealView ARM C 编译器支持在给定的内存地址放置一个变量使用变量属性 at(address):

The RealView ARM C Compiler supports placing a variable at a given memory address using the variable attribute at(address):

int var __attribute__((at(0x40001000)));
var = 4;   // changes the memory located at 0x40001000

GCC 是否有类似的变量属性?

Does GCC have a similar variable attribute?

推荐答案

我不知道，但您可以轻松创建如下解决方法:

I don't know, but you can easily create a workaround like this:

int *var = (int*)0x40001000;
*var = 4;

它完全不是一回事，但在大多数情况下是完美的替代品.它适用于任何编译器，而不仅仅是 GCC.

It's not exactly the same thing, but in most situations a perfect substitute. It will work with any compiler, not just GCC.

如果您使用 GCC，我假设您也使用 GNU ld(当然，虽然这不确定)并且 ld 支持放置变量任何地方你想要它们.

If you use GCC, I assume you also use GNU ld (although it is not a certainty, of course) and ld has support for placing variables wherever you want them.

我认为让链接器完成这项工作很常见.

I imagine letting the linker do that job is pretty common.

受到@rib 回答的启发，我会补充一点，如果绝对地址用于某个控制寄存器，我会将 volatile 添加到指针定义中.如果只是内存，没关系.

Inspired by answer by @rib, I'll add that if the absolute address is for some control register, I'd add volatile to the pointer definition. If it is just RAM, it doesn't matter.

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