linux device drivers 4th edition

Skb_release_data function has 0xc4 so large, and oops occurs at 0x74 place. So let's take a look at where the Skb_release_data starts:#grep Skb_release_data./system.mapC0282AF4 T Skb_release_dataSo we know that when the system error occurs, the program pointer is c0282af4+0x74=c0282b68(2) Then use GDB to view the GDB./vmlinux (executed under the Linux directory) and enter debug mode.gdb$ b *0xc0282b68Breakpoint 1 at 0xc0282b68:file NET/CORE/SKBUFF.C,

Misc Device driver. Also known as hybrid device driver.Misc Device driver shares a device driver number misc_major. It is defined in Include\linux\major.h: #define MISC_MAJOR the structure of the miscdevice is as follows, itDefined in Include\

, scheduling modes, and how to map them to the corresponding user space. It is equally important to port the RTOS hardware interface code to a more standardized Linux Device Driver in an I/O-intensive embedded program. This article will outline several common memory ing I/O methods that often appear in existing embedded applications. They cover a range from special use of interrupt service routines and acc

); void Iowrite16_rep (void *addr, const void *buf, unsigned long count); void Iowrite32_rep (void 8addr, const void *buf, unsigned long count); void Memset_io (void *addr, U8 value, unsigned int count); void Memcpy_fromio (void *dest, void *source, unsigned int count); void Memcpy_toio (void *dest, void *source, unsigned int count); unsigned readb (address); unsigned readw (address); unsigned readl (address); void Writeb (u

Fail_device_create;}return 0;Fail_device_create:Class_destroy (Dev_class);Fail_class_create:Cdev_del (demo_cdev);Fail_cdev_add:Unregister_chrdev_region (Dev, demo_count);Fail_register_chrdev:return ret;}void __exit demo_exit (void) {PRINTK ("Enter demo_exit () \ n");Device_destroy (Dev_class, Dev);Class_destroy (Dev_class);Cdev_del (demo_cdev);Unregister_chrdev_region (Dev, demo_count);}Module_init (Demo_init);Module_exit (Demo_exit);Ii.. Makefile Documents/* Makefile */Ifneq ($ (kernelrelease)

locks and semaphores take the form of "get lock-access critical section-release lock".*************************************************************************************************************** **********5. MutexThe mutex and the semaphore are basically the same. Not introduced.Summary: Concurrency and race are widespread, these mechanisms are a good way to solve the problem, interrupt masking is rarely used alone, atomic operations can only be done for integers, so the spin lock and signal

In the fourth chapter of the book "Linux device Drivers", we specialize in the debugging technology in driver development.PRINTK is just one of the techniques that requires PRINTK to print messages and write to files on disk, which slows down the entire code execution speed.There are also debugging techniques, and the effect on Code execution speed is smaller tha

); Read-copy-update Read-copy-update (RCU) is also an advanced mutex mechanism. Rarely used in drivers Http://www.rdrop.com/users/paulmck/rclock/intro/rclock_intro.html Optimized for situations where reads are frequent and rarely written The protected resource should be accessed through a pointer When the data structure needs to be modified, the write thread replicates first,

For more information about linux Device Drivers-general Linux technology-Linux programming and kernel, see the following. The device driver in linux is not as difficult as you think. To

question: I want to know what modules are built into the kernel in the Linux system and what parameters each module has. Is there a way to get a list of built-in modules and device drivers, along with their detailed information? The modern Linux kernel is growing rapidly over time to support a large number of hardware

. How to implement these operations is a task of every programmer, because the devices are specific. The key is how to organize the command code, because the command code in IOCTL is the only way to contact the user program command and driver support. In Linux, the core definesCommand codeOf:____________________________________ | Device type | serial number | direction | data size | | ---------- | --------

Because of work needs, now we need to learn the Linux Device Driver. Starting from the simplest character device driver, we need to record our learning experience and stick to our own ideas and conclusions. The makefile I wrote for the first hello World character driver is as follows: # Kvers = $ (shell uname-R) Ifneq ($ (kernelrelease ),) OBJ-M + = hello_world.

1. Write Linux device driver, require engineers have a certain hardware foundation, know how SRAM, Flash, SDRAM, disk read and write,The interface of UART, I²c, USB and other devices, polling, interrupt, DMA principle, PCI bus working mode and CPU memory management MMU.2. Have a good C language Foundation, can flexibly use the structure, pointers, function pointers and memory dynamic application and release

); List_head (list); List_add (struct list_head *new, struct list_head *head); List_add_tail (struct list_head *new, struct list_head *head); List_del (struct list_head *entry); List_del_init (struct list_head *entry); List_move (struct list_head *entry, struct list_head *head); List_move_tail (struct list_head *entry, struct list_head *head); List_empty (struct list_head *head); List_splice (struct list_head *list, struct list_head *head);

-safe version: Unsigned int read_seqbegin_irqsave (seqlock_t *lock, unsigned long flags); int Read_seqretry_irqrestore (seqlock_t *lock,unsigned int seq, unsigned long flags);The writer must obtain a mutex when entering a critical section protected by Seqlock: void Write_seqlock (seqlock_t *lock); void Write_sequnlock (seqlock_t *lock);Since write locks are implemented using spin locks, spin locks control write access, so common variants of the spin lock can be used: void Write_seqlock_irqsave (

(struct work_struct *work, void (*function) (void *), void *data); int queue_work (struct workqueue_struct *queue, struct work_struct *work); int queue_delayed_work (struct workqueue_struct *queue, struct work_struct *work, unsigned long delay); The return value of the above two functions is nonzero means that the given work_struct structure is already waiting in the queue int cancel_delayed_work (struct work_struct *work); The entry

Two important struct cdev and file_operations are involved here. The former is the descriptive character device, and the latter is the entry point of the device driver. For the description of the member with file_operations, please refer to the resolutions in file_operations I use the figure below to show the character device registration for the new version afte

; Init_list_head (list); List_head (list); List_add (struct list_head *new, struct list_head *head); List_add_tail (struct list_head *new, struct list_head *head); List_del (struct list_head *entry); List_del_init (struct list_head *entry); List_move (struct list_head *entry, struct list_head *head); List_move_tail (struct list_head *entry, struct list_head *head); List_empty (struct list_head *head); List_splice (struct list_

Memdev.h#ifndef _memdev_h#define _memdev_h#define mem_magic ' m ' #define Mem_restart _io (mem_magic, 0)//Use the kernel-provided macros to generate commands #define MEM _set _iow (mem_magic, 1, int)//change command to pass a shaping parameter to the kernel #endifDriver MEMDEV.C#include Application MEM_READ.C#include The device number is dynamically assigned in the driver and the device number assigned

atomic variable, assigned a value of 1*/ Static intXxx_open (structInode *inode,structFile *Filp) { ... if(!atomic_dec_and_test (xxx_available))/*A test value of 0 returns true otherwise false*/{atomic_inc (xxx_available); return-Ebusy;/*has been opened*/ } ... return 0;/*Success*/ } Static intXxx_release (structInode *inode,structFile *Filp) {Atomic_inc (xxx_available);/*releasing the device*/ return 0; }Spin lockspin