[英]how to compile a kernel module
I'm trying to compile a simple hello world module following this guide and I'm confused about what the Makefile is actually doing. 我正在尝试按照本指南编译一个简单的hello world模块,我对Makefile实际上在做什么感到困惑。
obj-m += hello-1.o
all:
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
clean:
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
I understand that when i type the make
command it will run the all
recipe which runs make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
. 据我所知,当我输入make
命令时,它将运行运行make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
的all
配方。 So now it runs the Makefile found at the path given after the -C
flag but what does the M=$(PWD) modules
do? 所以现在它运行在-C
标志之后给出的路径上找到的Makefile但是M=$(PWD) modules
做了什么?
' all and clean ' :- If you run 'make' by default it will run "all :". ' all and clean ': - 如果你默认运行'make',它将运行“all:”。 But we can use all and clean with make. 但我们可以使用all和clean with make。 it will run only those specific command. 它只会运行那些特定的命令。
Example :- 'make all' will run "make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules" 'make clean will run "make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean"
3.' 3.” uname -r ' :- get name and information about current kernel. uname -r ': - 获取有关当前内核的名称和信息。
Example :- for me, my kernel is "4.6.0-rc1".
Option ' -C dir ' :- Change to directory dir before reading the makefiles. 选项' -C dir ': - 在读取makefile之前更改目录dir。
Example :- "make -C /lib/modules/$(shell uname -r)/build" will change to "make -C /lib/modules/4.6.0-rc1/build.
Now you want to create your loadable module by using " make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules". 现在,您希望使用“ make -C / lib / modules / $(shell uname -r)/ build M = $(PWD) modules”来创建可加载模块。
Your source code need environment to run. 您的源代码需要运行环境。 That's why we have to use -C option to change build directory. 这就是我们必须使用-C选项来更改构建目录的原因。 Which have all needed definition, header file, Macro and etc. Now after changing to build directory you need to tell where is your module present, that's why we are using M=$PWD. 哪些都需要定义,头文件,宏等等。现在更改为构建目录后,您需要告诉您的模块在哪里,这就是我们使用M = $ PWD的原因。
To compile kernel module, the make
command you normally need is in this form: 要编译内核模块,您通常需要的make
命令采用以下形式:
make -C /lib/modules/3.16.0-70-generic/build M=/home/test/ldd3/hello modules
in which, -C
means switching to another path. 其中, -C
表示切换到另一条路径。
/lib/modules/3.16.0-70-generic/
is the path to the kernel in used, and 是使用中的内核的路径,和
/home/test/ldd3/hello
is where the source of your module resides. 是模块源所在的位置。
what does the M=$(PWD) modules do? M = $(PWD)模块有什么作用?
So as I said M=$(PWD)
is simply a shell variable that stores the current path to your kernel module. 所以我说M=$(PWD)
只是一个shell变量,它存储了内核模块的当前路径。 make
needs to store this as it switches to the kernel build path. make
需要在切换到内核构建路径时存储它。
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