Material und Beispiele 30.4.2021

20210430/Makefile

+Makefile-modules-2
\ No newline at end of file

20210430/Makefile-1

+hello-3: hello-3.c
+	gcc -Wall -O hello-3.c -o hello-3

20210430/Makefile-2

+TARGET = hello-3
+CFLAGS = -Wall -O
+
+$(TARGET): hello-3.c
+	gcc $(CFLAGS) hello-3.c -o hello-3

20210430/Makefile-3

+TARGET = hello-3
+CFLAGS = -Wall -O
+
+$(TARGET): $(TARGET).c
+	gcc $(CFLAGS) $< -o $(TARGET)

20210430/Makefile-modules-1

+obj-m += hellomod-1.o
+
+# obj-m += hellomod-2.o
+# obj-m += chardev-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

20210430/Makefile-modules-2

+obj-m = hellomod-1.o
+obj-m += hellomod-2.o
+obj-m += chardev-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

20210430/chardev-1.c

+/*
+ *  chardev.c: Creates a read-only char device that says how many times
+ *  you've read from the dev file
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <asm/uaccess.h>	/* for put_user */
+
+/*  
+ *  Prototypes - this would normally go in a .h file
+ */
+int init_module(void);
+void cleanup_module(void);
+static int device_open(struct inode *, struct file *);
+static int device_release(struct inode *, struct file *);
+static ssize_t device_read(struct file *, char *, size_t, loff_t *);
+static ssize_t device_write(struct file *, const char *, size_t, loff_t *);
+
+#define SUCCESS 0
+#define DEVICE_NAME "chardev"	/* Dev name as it appears in /proc/devices   */
+#define BUF_LEN 80		/* Max length of the message from the device */
+
+/* 
+ * Global variables are declared as static, so are global within the file. 
+ */
+
+static int Major;		/* Major number assigned to our device driver */
+static int Device_Open = 0;	/* Is device open?  
+				 * Used to prevent multiple access to device */
+static char msg[BUF_LEN];	/* The msg the device will give when asked */
+static char *msg_Ptr;
+
+static struct file_operations fops = {
+	.read = device_read,
+	.write = device_write,
+	.open = device_open,
+	.release = device_release
+};
+
+/*
+ * This function is called when the module is loaded
+ */
+int init_module(void)
+{
+        Major = register_chrdev(0, DEVICE_NAME, &fops);
+
+	if (Major < 0) {
+	  printk(KERN_ALERT "Registering char device failed with %d\n", Major);
+	  return Major;
+	}
+
+	printk(KERN_INFO "I was assigned major number %d. To talk to\n", Major);
+	printk(KERN_INFO "the driver, create a dev file with\n");
+	printk(KERN_INFO "'mknod /dev/%s c %d 0'.\n", DEVICE_NAME, Major);
+	printk(KERN_INFO "Try various minor numbers. Try to cat and echo to\n");
+	printk(KERN_INFO "the device file.\n");
+	printk(KERN_INFO "Remove the device file and module when done.\n");
+
+	return SUCCESS;
+}
+
+/*
+ * This function is called when the module is unloaded
+ */
+void cleanup_module(void)
+{
+	/* 
+	 * Unregister the device 
+	 */
+	unregister_chrdev(Major, DEVICE_NAME);
+}
+
+/*
+ * Methods
+ */
+
+/* 
+ * Called when a process tries to open the device file, like
+ * "cat /dev/mycharfile"
+ */
+static int device_open(struct inode *inode, struct file *file)
+{
+	static int counter = 0;
+
+	if (Device_Open)
+		return -EBUSY;
+
+	Device_Open++;
+	sprintf(msg, "I already told you %d times Hello world!\n", counter++);
+	msg_Ptr = msg;
+	try_module_get(THIS_MODULE);
+
+	return SUCCESS;
+}
+
+/* 
+ * Called when a process closes the device file.
+ */
+static int device_release(struct inode *inode, struct file *file)
+{
+	Device_Open--;		/* We're now ready for our next caller */
+
+	/* 
+	 * Decrement the usage count, or else once you opened the file, you'll
+	 * never get get rid of the module. 
+	 */
+	module_put(THIS_MODULE);
+
+	return 0;
+}
+
+/* 
+ * Called when a process, which already opened the dev file, attempts to
+ * read from it.
+ */
+static ssize_t device_read(struct file *filp,	/* see include/linux/fs.h   */
+			   char *buffer,	/* buffer to fill with data */
+			   size_t length,	/* length of the buffer     */
+			   loff_t * offset)
+{
+	/*
+	 * Number of bytes actually written to the buffer 
+	 */
+	int bytes_read = 0;
+
+	/*
+	 * If we're at the end of the message, 
+	 * return 0 signifying end of file 
+	 */
+	if (*msg_Ptr == 0)
+		return 0;
+
+	/* 
+	 * Actually put the data into the buffer 
+	 */
+	while (length && *msg_Ptr) {
+
+		/* 
+		 * The buffer is in the user data segment, not the kernel 
+		 * segment so "*" assignment won't work.  We have to use 
+		 * put_user which copies data from the kernel data segment to
+		 * the user data segment. 
+		 */
+		put_user(*(msg_Ptr++), buffer++);
+
+		length--;
+		bytes_read++;
+	}
+
+	/* 
+	 * Most read functions return the number of bytes put into the buffer
+	 */
+	return bytes_read;
+}
+
+/*  
+ * Called when a process writes to dev file: echo "hi" > /dev/hello 
+ */
+static ssize_t
+device_write(struct file *filp, const char *buff, size_t len, loff_t * off)
+{
+	printk(KERN_ALERT "Sorry, this operation isn't supported.\n");
+	return -EINVAL;
+}

20210430/chardev-2.c

+/*
+ *  chardev.c: Creates a read-only char device that says how many times
+ *  you've read from the dev file
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <asm/uaccess.h>	/* for put_user */
+
+/*  
+ *  Prototypes - this would normally go in a .h file
+ */
+int init_module(void);
+void cleanup_module(void);
+static int device_open(struct inode *, struct file *);
+static int device_release(struct inode *, struct file *);
+static ssize_t device_read(struct file *, char *, size_t, loff_t *);
+static ssize_t device_write(struct file *, const char *, size_t, loff_t *);
+
+struct class *dev_Class;
+struct device *chr_dev;
+
+#define SUCCESS 0
+#define DEVICE_NAME "chardev"	/* Dev name as it appears in /proc/devices   */
+#define BUF_LEN 80		/* Max length of the message from the device */
+
+/* 
+ * Global variables are declared as static, so are global within the file. 
+ */
+
+static int Major;		/* Major number assigned to our device driver */
+static int Device_Open = 0;	/* Is device open?  
+				 * Used to prevent multiple access to device */
+static char msg[BUF_LEN];	/* The msg the device will give when asked */
+static char *msg_Ptr;
+
+static struct file_operations fops = {
+	.read = device_read,
+	.write = device_write,
+	.open = device_open,
+	.release = device_release
+};
+
+/*
+ * This function is called when the module is loaded
+ */
+int init_module(void)
+{
+        Major = register_chrdev(0, DEVICE_NAME, &fops);
+
+	if (Major < 0) {
+	  printk(KERN_ALERT "Registering char device failed with %d\n", Major);
+	  return Major;
+	}
+
+        // Create module class
+        printk(KERN_INFO "Creating device class LCD...\n");
+        dev_Class = class_create(THIS_MODULE,DEVICE_NAME);
+        if( dev_Class == NULL)
+        {
+            printk( KERN_ALERT "Error! Class couldn't be created!\n" );
+            return 1 ;
+        }
+        printk( KERN_INFO "Class created!\n" );
+        // Create device in /dev/...
+        printk(KERN_INFO "Creating device\n");
+        chr_dev = device_create(dev_Class, NULL, MKDEV(Major,0), NULL, DEVICE_NAME);
+
+	printk(KERN_INFO "I was assigned major number %d. To talk to\n", Major);
+	printk(KERN_INFO "the driver, create a dev file with\n");
+	printk(KERN_INFO "'mknod /dev/%s c %d 0'.\n", DEVICE_NAME, Major);
+	printk(KERN_INFO "Try various minor numbers. Try to cat and echo to\n");
+	printk(KERN_INFO "the device file.\n");
+	printk(KERN_INFO "Remove the device file and module when done.\n");
+
+	return SUCCESS;
+}
+
+/*
+ * This function is called when the module is unloaded
+ */
+void cleanup_module(void)
+{
+	/* 
+	 * Unregister the device 
+	 */
+	unregister_chrdev(Major, DEVICE_NAME);
+}
+
+/*
+ * Methods
+ */
+
+/* 
+ * Called when a process tries to open the device file, like
+ * "cat /dev/mycharfile"
+ */
+static int device_open(struct inode *inode, struct file *file)
+{
+	static int counter = 0;
+
+	if (Device_Open)
+		return -EBUSY;
+
+	Device_Open++;
+	sprintf(msg, "I already told you %d times Hello world!\n", counter++);
+	msg_Ptr = msg;
+	try_module_get(THIS_MODULE);
+
+	return SUCCESS;
+}
+
+/* 
+ * Called when a process closes the device file.
+ */
+static int device_release(struct inode *inode, struct file *file)
+{
+	Device_Open--;		/* We're now ready for our next caller */
+
+	/* 
+	 * Decrement the usage count, or else once you opened the file, you'll
+	 * never get get rid of the module. 
+	 */
+	module_put(THIS_MODULE);
+
+	return 0;
+}
+
+/* 
+ * Called when a process, which already opened the dev file, attempts to
+ * read from it.
+ */
+static ssize_t device_read(struct file *filp,	/* see include/linux/fs.h   */
+			   char *buffer,	/* buffer to fill with data */
+			   size_t length,	/* length of the buffer     */
+			   loff_t * offset)
+{
+	/*
+	 * Number of bytes actually written to the buffer 
+	 */
+	int bytes_read = 0;
+
+	/*
+	 * If we're at the end of the message, 
+	 * return 0 signifying end of file 
+	 */
+	if (*msg_Ptr == 0)
+		return 0;
+
+	/* 
+	 * Actually put the data into the buffer 
+	 */
+	while (length && *msg_Ptr) {
+
+		/* 
+		 * The buffer is in the user data segment, not the kernel 
+		 * segment so "*" assignment won't work.  We have to use 
+		 * put_user which copies data from the kernel data segment to
+		 * the user data segment. 
+		 */
+		put_user(*(msg_Ptr++), buffer++);
+
+		length--;
+		bytes_read++;
+	}
+
+	/* 
+	 * Most read functions return the number of bytes put into the buffer
+	 */
+	return bytes_read;
+}
+
+/*  
+ * Called when a process writes to dev file: echo "hi" > /dev/hello 
+ */
+static ssize_t
+device_write(struct file *filp, const char *buff, size_t len, loff_t * off)
+{
+	printk(KERN_ALERT "Sorry, this operation isn't supported.\n");
+	return -EINVAL;
+}

20210430/chardev-3.c

+/*
+ *  chardev.c: Creates a read-only char device that says how many times
+ *  you've read from the dev file
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <asm/uaccess.h>	/* for put_user */
+
+MODULE_LICENSE("GPL");
+
+/*  
+ *  Prototypes - this would normally go in a .h file
+ */
+int init_module(void);
+void cleanup_module(void);
+static int device_open(struct inode *, struct file *);
+static int device_release(struct inode *, struct file *);
+static ssize_t device_read(struct file *, char *, size_t, loff_t *);
+static ssize_t device_write(struct file *, const char *, size_t, loff_t *);
+
+struct class *dev_Class;
+struct device *chr_dev;
+
+#define SUCCESS 0
+#define DEVICE_NAME "chardev"	/* Dev name as it appears in /proc/devices   */
+#define BUF_LEN 80		/* Max length of the message from the device */
+
+/* 
+ * Global variables are declared as static, so are global within the file. 
+ */
+
+static int Major;		/* Major number assigned to our device driver */
+static int Device_Open = 0;	/* Is device open?  
+				 * Used to prevent multiple access to device */
+static char msg[BUF_LEN];	/* The msg the device will give when asked */
+static char *msg_Ptr;
+
+static struct file_operations fops = {
+	.read = device_read,
+	.write = device_write,
+	.open = device_open,
+	.release = device_release
+};
+
+/*
+ * This function is called when the module is loaded
+ */
+int init_module(void)
+{
+        Major = register_chrdev(0, DEVICE_NAME, &fops);
+
+	if (Major < 0) {
+	  printk(KERN_ALERT "Registering char device failed with %d\n", Major);
+	  return Major;
+	}
+
+        // Create module class
+        printk (KERN_INFO "Creating device class \"chardev\" ...\n");
+        dev_Class = class_create (THIS_MODULE,DEVICE_NAME);
+        if( dev_Class == NULL)
+        {
+            printk (KERN_ALERT "Error! Class couldn't be created!\n");
+            return 1;
+        }
+        printk (KERN_INFO "Class created!\n");
+        // Create device in /dev/...
+        printk (KERN_INFO "Creating device\n");
+        chr_dev = device_create (dev_Class, NULL, MKDEV (Major,0), NULL, DEVICE_NAME);
+        if (chr_dev == NULL)
+        {
+            printk( KERN_ALERT "Error! Device couldn't be created!\n" );
+            return 1 ;
+        }
+
+	return SUCCESS;
+}
+
+/*
+ * This function is called when the module is unloaded
+ */
+void cleanup_module(void)
+{
+        printk(KERN_INFO "module chardev-4 cleanup\n");
+        //Unregister the device
+        if (chr_dev)
+          {
+            printk(KERN_INFO "Unregister device ...\n");
+            device_unregister(chr_dev);
+            printk(KERN_INFO "OK\n");
+          }
+
+        if (dev_Class)
+          {
+            printk(KERN_INFO "Unregister class ...\n");
+            class_unregister(dev_Class);
+            printk(KERN_INFO "OK\n");
+          }
+
+        printk(KERN_INFO "Unregister Chardev ...\n");
+        unregister_chrdev(Major, DEVICE_NAME);
+        printk(KERN_INFO "Device %s unregistered!\n", DEVICE_NAME);
+}
+
+/*
+ * Methods
+ */
+
+/* 
+ * Called when a process tries to open the device file, like
+ * "cat /dev/mycharfile"
+ */
+static int device_open(struct inode *inode, struct file *file)
+{
+	static int counter = 0;
+
+	if (Device_Open)
+		return -EBUSY;
+
+	Device_Open++;
+	sprintf(msg, "I already told you %d times Hello world!\n", counter++);
+	msg_Ptr = msg;
+	try_module_get(THIS_MODULE);
+
+	return SUCCESS;
+}
+
+/* 
+ * Called when a process closes the device file.
+ */
+static int device_release(struct inode *inode, struct file *file)
+{
+	Device_Open--;		/* We're now ready for our next caller */
+
+	/* 
+	 * Decrement the usage count, or else once you opened the file, you'll
+	 * never get get rid of the module. 
+	 */
+	module_put(THIS_MODULE);
+
+	return 0;
+}
+
+/* 
+ * Called when a process, which already opened the dev file, attempts to
+ * read from it.
+ */
+static ssize_t device_read(struct file *filp,	/* see include/linux/fs.h   */
+			   char *buffer,	/* buffer to fill with data */
+			   size_t length,	/* length of the buffer     */
+			   loff_t * offset)
+{
+	/*
+	 * Number of bytes actually written to the buffer 
+	 */
+	int bytes_read = 0;
+
+	/*
+	 * If we're at the end of the message, 
+	 * return 0 signifying end of file 
+	 */
+	if (*msg_Ptr == 0)
+		return 0;
+
+	/* 
+	 * Actually put the data into the buffer 
+	 */
+	while (length && *msg_Ptr) {
+
+		/* 
+		 * The buffer is in the user data segment, not the kernel 
+		 * segment so "*" assignment won't work.  We have to use 
+		 * put_user which copies data from the kernel data segment to
+		 * the user data segment. 
+		 */
+		put_user(*(msg_Ptr++), buffer++);
+
+		length--;
+		bytes_read++;
+	}
+
+	/* 
+	 * Most read functions return the number of bytes put into the buffer
+	 */
+	return bytes_read;
+}
+
+/*  
+ * Called when a process writes to dev file: echo "hi" > /dev/hello 
+ */
+static ssize_t
+device_write(struct file *filp, const char *buff, size_t len, loff_t * off)
+{
+	printk(KERN_ALERT "Sorry, this operation isn't supported.\n");
+	return -EINVAL;
+}

20210430/hello-1.c

+#include <stdio.h>
+
+int main (void)
+{
+  printf ("");
+  printf ("H");
+  printf ("e");
+  printf ("l");
+  printf ("l");
+  printf ("o");
+  return 0;
+}

20210430/hello-2.c

+#include <stdio.h>
+
+int main (void)
+{
+  printf ("\x1b[H\x1b[J");
+  printf ("\x1b[00m\x1b[01;35m");
+  printf ("Hello, world!\n");
+  return 0;
+}

20210430/hello-3.c

+#include <stdio.h>
+
+int main (void)
+{
+  printf ("Hello, world!\n");
+  return 0;
+}

20210430/hellomod-1.c

+/*  
+ *  hello-1.c - The simplest kernel module.
+ */
+#include <linux/module.h>	/* Needed by all modules */
+#include <linux/kernel.h>	/* Needed for KERN_INFO */
+
+int init_module(void)
+{
+	printk(KERN_INFO "Hello world 1.\n");
+
+	/* 
+	 * A non 0 return means init_module failed; module can't be loaded. 
+	 */
+	return 0;
+}
+
+void cleanup_module(void)
+{
+	printk(KERN_INFO "Goodbye world 1.\n");
+}

20210430/hellomod-2.c

+/*  
+ *  hello-2.c - The simplest kernel module.
+ */
+#include <linux/module.h>	/* Needed by all modules */
+#include <linux/kernel.h>	/* Needed for KERN_INFO */
+
+MODULE_LICENSE("GPL");
+
+int init_module(void)
+{
+	printk(KERN_INFO "Hello world 2.\n");
+
+	/* 
+	 * A non 0 return means init_module failed; module can't be loaded. 
+	 */
+	return 0;
+}
+
+void cleanup_module(void)
+{
+	printk(KERN_INFO "Goodbye world 2.\n");
+}

20210430/make-1.txt

+cassini/home/peter/bo/2021ss/bs/20210430> cat Makefile
+hello-3: hello-3.c
+        gcc -Wall -O hello-3.c -o hello-3
+cassini/home/peter/bo/2021ss/bs/20210430> cat hello-3.c
+#include <stdio.h>
+
+int main (void)
+{
+  printf ("Hello, world!\n");
+  return 0;
+}
+cassini/home/peter/bo/2021ss/bs/20210430> make
+gcc -Wall -O hello-3.c -o hello-3
+cassini/home/peter/bo/2021ss/bs/20210430> ./hello-3
+Hello, world!
+cassini/home/peter/bo/2021ss/bs/20210430> make
+make: „hello-3“ ist bereits aktuell.
+cassini/home/peter/bo/2021ss/bs/20210430> touch hello-3.c
+cassini/home/peter/bo/2021ss/bs/20210430> ls -lrt
+insgesamt 1120
+-rw-r--r-- 1 peter peter 1048576 Okt 22  2013 freedos.hd
+-rw-r--r-- 1 peter peter    4069 Apr  4  2014 chardev-1.c
+-rw-r--r-- 1 peter peter     390 Apr  4  2014 hellomod-1.c
+-rw-r--r-- 1 peter peter    4659 Mai  5  2017 chardev-2.c
+-rw-r--r-- 1 peter peter     414 Apr 26  2019 hellomod-2.c
+-rw-r--r-- 1 peter peter    4997 Apr 26  2019 chardev-3.c
+-rw-r--r-- 1 peter peter     230 Apr 30 12:06 SCRATCH
+-rw-r--r-- 1 peter peter     210 Apr 30 12:25 nix-hello.c
+-rw-r--r-- 1 peter peter     185 Apr 30 12:33 hello-1.c
+-rw-r--r-- 1 peter peter     143 Apr 30 12:36 hello-2.c
+-rwxr-xr-x 1 peter peter   16608 Apr 30 12:40 a.out
+-rw-r--r-- 1 peter peter     208 Apr 30 12:52 Makefile-1
+-rw-r--r-- 1 peter peter      54 Apr 30 12:55 Makefile
+-rwxr-xr-x 1 peter peter   16608 Apr 30 12:55 hello-3
+-rw-r--r-- 1 peter peter      82 Apr 30 12:56 hello-3.c
+cassini/home/peter/bo/2021ss/bs/20210430> make
+gcc -Wall -O hello-3.c -o hello-3
+cassini/home/peter/bo/2021ss/bs/20210430> ./hello-3
+Hello, world!
+cassini/home/peter/bo/2021ss/bs/20210430>

20210430/make-2.txt

+TARGET = hello-3
+CFLAGS = -Wall -O
+
+$(TARGET): hello-3.c
+        gcc $(CFLAGS) hello-3.c -o hello-3
+cassini/home/peter/bo/2021ss/bs/20210430> make
+make: „hello-3“ ist bereits aktuell.
+cassini/home/peter/bo/2021ss/bs/20210430> touch hello-3.c
+cassini/home/peter/bo/2021ss/bs/20210430> make
+gcc -Wall -O hello-3.c -o hello-3
+cassini/home/peter/bo/2021ss/bs/20210430>

20210430/make-3.txt

+TARGET = hello-3
+CFLAGS = -Wall -O
+
+$(TARGET): $(TARGET).c
+        gcc $(CFLAGS) $< -o $(TARGET)
+cassini/home/peter/bo/2021ss/bs/20210430> touch hello-3.c
+cassini/home/peter/bo/2021ss/bs/20210430> make
+gcc -Wall -O hello-3.c -o hello-3
+cassini/home/peter/bo/2021ss/bs/20210430>

20210430/make-4.txt

+cassini/home/peter/bo/2020ws/hp/20201217> cat philosophy.c
+#include <stdio.h>
+#include "answer.h"
+
+int main (void)
+{
+  printf ("The answer is %d.\n", answer ());
+  return 0;
+}
+cassini/home/peter/bo/2020ws/hp/20201217> cat answer.h
+extern int answer (void);
+cassini/home/peter/bo/2020ws/hp/20201217> gcc -Wall -O philosophy.c -o philosophy
+/usr/bin/ld: /tmp/ccPlT8mv.o: in function `main':
+philosophy.c:(.text+0x5): undefined reference to `answer'
+collect2: error: ld returned 1 exit status
+cassini/home/peter/bo/2020ws/hp/20201217> cat answer.c
+#include "answer.h"
+
+int answer (void)
+{
+  return 23;
+}
+cassini/home/peter/bo/2020ws/hp/20201217> gcc -Wall -O philosophy.c answer.c -o philosophy
+cassini/home/peter/bo/2020ws/hp/20201217> ./philosophy
+The answer is 23.
+cassini/home/peter/bo/2020ws/hp/20201217>

20210430/make-5.txt

+cassini/home/peter/bo/2020ws/hp/20201217> gcc -Wall -O philosophy.c -c
+cassini/home/peter/bo/2020ws/hp/20201217> ls -l philosophy*
+-rwxr-xr-x 1 peter peter 16680 Apr 30 14:18 philosophy
+-rw-r--r-- 1 peter peter   117 Jan  4 14:29 philosophy.c
+-rw-r--r-- 1 peter peter  1632 Apr 30 14:19 philosophy.o
+cassini/home/peter/bo/2020ws/hp/20201217> gcc -Wall -O answer.c -c
+cassini/home/peter/bo/2020ws/hp/20201217> ls -l answer.*
+-rw-r--r-- 1 peter peter   56 Jan  4 14:29 answer.c
+-rw-r--r-- 1 peter peter   26 Jan  4 14:29 answer.h
+-rw-r--r-- 1 peter peter 1208 Apr 30 14:20 answer.o
+cassini/home/peter/bo/2020ws/hp/20201217> gcc philosophy.o answer.o -o philosophy
+cassini/home/peter/bo/2020ws/hp/20201217> ./philosophy
+The answer is 23.
+cassini/home/peter/bo/2020ws/hp/20201217>