3rd-party/linux-kernel-module-cheat
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split kernel module api docs to README

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Ciro Santilli
2018-07-01 23:37:37 +01:00
parent 8f37cd0d22
commit 6c241279a6
18 changed files with 490 additions and 296 deletions
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69
kernel_module/params.c
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@@ -1,68 +1,53 @@
/*
Allows passing parameters at insertion time.
Those parameters can also be read and modified at runtime from /sys.
insmod /params.ko
# dmesg => 0 0
cd /sys/module/params/parameters
cat i
# => 1 0
printf 1 >i
# dmesg => 1 0
rmmod params
insmod /params.ko i=1 j=1
# dmesg => 1 1
rmmod params
modinfo
/params.ko
# Output contains MODULE_PARAM_DESC descriptions.
modprobe insertion can also set default parameters via the /etc/modprobe.conf file. So:
modprobe params
Outputs:
12 34
*/
/* https://github.com/cirosantilli/linux-kernel-module-cheat#kernel-module-parameters */
#include <linux/debugfs.h>
#include <linux/delay.h> /* usleep_range */
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/seq_file.h> /* seq_read, seq_lseek, single_release */
#include <uapi/linux/stat.h> /* S_IRUSR | S_IWUSR */
static int i = 0;
static int j = 0;
static u32 i = 0;
static u32 j = 0;
module_param(i, int, S_IRUSR | S_IWUSR);
module_param(j, int, S_IRUSR | S_IWUSR);
MODULE_PARM_DESC(i, "my favorite int");
MODULE_PARM_DESC(j, "my second favorite int");
static struct task_struct *kthread;
static struct dentry *debugfs_file;
static int work_func(void *data)
static int show(struct seq_file *m, void *v)
{
while (!kthread_should_stop()) {
pr_info("%d %d\n", i, j);
usleep_range(1000000, 1000001);
}
char kbuf[18];
int ret;
ret = snprintf(kbuf, sizeof(kbuf), "%d %d", i, j);
seq_printf(m, kbuf);
return 0;
}
static int open(struct inode *inode, struct file *file)
{
return single_open(file, show, NULL);
}
static const struct file_operations fops = {
.llseek = seq_lseek,
.open = open,
.owner = THIS_MODULE,
.read = seq_read,
.release = single_release,
};
static int myinit(void)
{
kthread = kthread_create(work_func, NULL, "mykthread");
wake_up_process(kthread);
debugfs_file = debugfs_create_file("lkmc_params", S_IRUSR, NULL, NULL, &fops);
return 0;
}
static void myexit(void)
{
kthread_stop(kthread);
debugfs_remove(debugfs_file);
}
module_init(myinit)