如何使用 -std=gnu99 编译 Linux 内核模块? [英] How to compile a Linux kernel module using -std=gnu99?

问题描述

我最近学习了如何编写简单的字符驱动程序，在尝试编写代码时，我注意到我的 C99 代码收到了很多以下 GCC 警告:

I've recently learned how to program simple character drivers and while playing around with the code I noticed that I get a lot of the following GCC warnings thrown for my C99 code:

warning: ISO C90 forbids mixed declarations and code

我认为这是因为主 Linux 内核 Makefile 设置为使用非 C99 标准进行编译.我四处搜索我在stackoverflow上找到了这个答案:How使用 make 并编译为 C99?

I assume this is because the main Linux kernel Makefile is set to compile using a non-C99 standard. I searched around I found this answer here on stackoverflow: How to use make and compile as C99?

所以我很自然地在我的 Makefile 中尝试了以下内容:

So I naturally tried the following in my Makefile:

ccflags-y := -std=gnu99

不幸的是，这并没有消除 GCC 警告.我检查了 make 的详细输出，并验证了 GCC 确实是在最后添加了 -std=gnu99 的情况下执行的；所以我有点困惑.

Unfortunately this didn't silence the GCC warnings. I checked the verbose output of make and verified that GCC is indeed executed with the -std=gnu99 tacked on at the end; so I'm a bit confused.

如何使用 -std=gnu99 选项正确编译 Linux 内核模块?

How do I properly compile a Linux kernel module using the -std=gnu99 option?

编辑:

我注意到 GCC 输出显示了这个选项:-Wdeclaration-after-statement.这就是为什么即使使用 -std=gnu99 选项我也会收到警告?

I noticed the GCC output shows this option: -Wdeclaration-after-statement. Is this why I am getting the warnings even with the -std=gnu99 option?

推荐答案

事实证明 -std=gnu99 确实 确实有效；删除编译器标志后，我开始看到有关 C99 功能的错误.所以这意味着除了 -std= 选项之外，还有其他原因导致警告打印出来.

It turns out that -std=gnu99 does in fact work; I began seeing errors regarding C99 features after removing the compiler flag. So that meant something else was causing the warnings to print out besides the -std= option.

在通过 make V=1 解析详细输出后，我发现 -Wdeclaration-after-statement 选项是 GCC 执行的一部分.这就是我看到的 ISO C90 混合声明警告的原因.

After parsing through the verbose output via make V=1, I discovered the -Wdeclaration-after-statement option as part of the GCC execution. This was the cause of the ISO C90 mixed declaration warnings I saw.

要禁用 ISO C90 警告，请将其传递给 GCC:-Wno-declaration-after-statement.

To disable the ISO C90 warnings, pass this to GCC: -Wno-declaration-after-statement.

例如:

ccflags-y := -std=gnu99 -Wno-declaration-after-statement

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