Linux 驱动-4 模块传参

指针变量whom指向常量hello

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w@w:~/linux_kernel/param$ cat hello.c

#include

#include

static char *whom = "hello \n";

static int var = 1;

static int hello_init(void)

{

        printk("hello_init %s \n",whom);

        return 0;

}

static void hello_exit(void)

{

        printk("hello_exit  %d\n",var);

        return;

}

MODULE_LICENSE("GPL");

module_param(whom,charp,0644);

module_param_named(var_out,var,int,0644);

module_init(hello_init);

module_exit(hello_exit);

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w@w:~/linux_kernel/param$ cat Makefile

ifneq ($(KERNELRELEASE),)

$(info "2nd")

obj-m:=hello.o

else

KDIR :=/lib/modules/$(shell uname -r)/build

PWD  :=$(shell pwd)

all:

        $(info "1st")

        make -C $(KDIR) M=$(PWD) modules

clean:

        rm -f *.ko *.o *.mod.o *.symvers *.cmd  *.mod.c *.order

endif

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w@w:~/linux_kernel/param$ sudo make

"1st"

make -C /lib/modules/5.4.0-104-generic/build M=/home/w/linux_kernel/param modules

make[1]: Entering directory '/usr/src/linux-headers-5.4.0-104-generic'

"2nd"

  CC [M]  /home/w/linux_kernel/param/hello.o

"2nd"

  Building modules, stage 2.

  MODPOST 1 modules

  CC [M]  /home/w/linux_kernel/param/hello.mod.o

  LD [M]  /home/w/linux_kernel/param/hello.ko

make[1]: Leaving directory '/usr/src/linux-headers-5.4.0-104-generic'

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w@w:~/linux_kernel/param$ sudo insmod hello.ko

w@w:~/linux_kernel/param$ sudo dmesg -c

[13425.220292] helloa: module license 'unspecified' taints kernel.

[13425.220294] Disabling lock debugging due to kernel taint

[13425.220586] hello_init

[13630.617249] hello_init 100

[13630.617250] aaaa:  num =100

[14299.890225] hello_exit

[14312.594776] hello_exit

[16236.730997] hello_init hello

w@w:~/linux_kernel/param$ sudo rmmod hello.ko

w@w:~/linux_kernel/param$ dmesg

[16271.042902] hello_exit  1

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w@w:~/linux_kernel/param$ sudo insmod hello.ko var_out=5 whom="Jack"

w@w:~/linux_kernel/param$ dmesg

[16271.042902] hello_exit  1

[16475.521375] hello_init Jack

w@w:~/linux_kernel/param$ sudo rmmod hello.ko

w@w:~/linux_kernel/param$ dmesg

[16271.042902] hello_exit  1

[16475.521375] hello_init Jack

[16492.779499] hello_exit  5

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每加载一个内核模块，Linux系统就会在/sys/module下面为该模块建立一个文件夹。 hello.ko对应的就是/sys/module下面的hello 文件夹。 卸载模块时，该文件夹同时消失

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