mmap

will give you a great output about every system call of this program. These system calls may be added to your hacking LKM. I don't have such a hypervisor as an example. But let's look at the output of 'strace whoam: 　　 Execve ("/usr/bin/whoami", ["whoami"], [/* 50 vars */]) = 0 　　 Mmap (0, 4096, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS,-1, 0) = 　　 Zero x 40007000 　　 Mprotect (0x40000000,206 73, PROT_READ | PROT_WRITE | PROT_EXEC) = 0 　　 Mp

the registers of these devices, after the completion of access, using the Ioremap () The requested virtual address is released and frees the I/O memory resource for the relese_mem_region () request6. Map device address to user spaceIn general, user space cannot and should not be directly accessible to the device, however, the device driver can implement the mmap () function, the function of the user space can directly access the physical address of t

extension module. Then open php.ini and join: Copy Code code as follows: Extension=php_apc.dll apc.rfc1867 = On Apc.max_file_size = 100M Upload_max_filesize = 100M Post_max_size = 100M The above parameters can be defined by themselves Step three: Check to see if you support PHP APC apc_store apc_fetch See if there are APC dependencies in the Phpinfo Install APC under B.liunxFirst step: Download and installwget http://pecl.php.net/get/APC-3.1.8.tgzTAR-ZXVF apc-3.

php_apc.dll into your ext DirectoryStep 2: Let php. ini support the apc extension module. Then open php. ini and add: The code is as follows: extension = php_apc.dllApc. rfc1867 = onApc. max_file_size = 100 MUpload_max_filesize = 100 MPost_max_size = 100 M// You can customize the preceding parameters.Step 3: Check whether php apc apc_store apc_fetch is supportedCheck whether apc related items exist in phpinfo. B. install APC in LIUNXStep 1: Download and InstallWget http://pecl.php.net/get/APC-3

the disk and stores it in the kernel address buffer. In the second step, the data is copied from the kernel buffer into the user buffer, read() returned, and the context switches back to the user state. The third step, the write() context switch, copies the buffer to the kernel address buffer. Fourth step, write() return, fourth context switch, DMA engine transmits the data from the kernel buffer to the protocol engine, usually enters the queue, waits for the transmission. We see t

V4L2 driver (1). Overall framework, v4l2driver 1.1 starting from character Devices Anyone familiar with v4l2 user space programming knows that v4l2 programming mainly calls a series of ioctl functions to open, close, query, and set v4l2 devices. the v4l2 device is a character device, and the main task of its driver is to implement a variety of ioctl .?Shows the overall framework of v4l2. What is the overall framework of V4L2? The light green background is the user space, and the light bl

module. Then open php.ini join:Copy the Code code as follows: Extension=php_apc.dllapc.rfc1867 = OnApc.max_file_size = 100MUpload_max_filesize = 100MPost_max_size = 100MThe above parameters can be defined by themselvesStep three: Check if PHP APC apc_store Apc_fetch is supportedSee if there are APC related items in the Phpinfo installing APC under B.liunxFirst step: Download and installwget http://pecl.php.net/get/APC-3.1.8.tgzTAR-ZXVF apc-3.1.8.tgz CD APC-3.1.8/usr/local/php/bin/phpize./config

module. Then open php.ini join:Copy the Code code as follows: Extension=php_apc.dllapc.rfc1867 = OnApc.max_file_size = 100MUpload_max_filesize = 100MPost_max_size = 100MThe above parameters can be defined by themselvesStep three: Check if PHP APC apc_store Apc_fetch is supportedSee if there are APC related items in the Phpinfo installing APC under B.liunxFirst step: Download and installwget http://pecl.php.net/get/APC-3.1.8.tgzTAR-ZXVF apc-3.1.8.tgz CD APC-3.1.8/usr/local/php/bin/phpize./config

, performance Loss. Second, the cache for receiving data should be provided by the receiver, but the receiver does not know how much cache is required, you can only open up as much space as possible or call the API to receive the message header to obtain the message body size, and then open up an appropriate space to receive the message body. Both methods are insufficient, either a waste of space or time. The binder adopts a new policy: the binder driver is responsible for managing the data rece

, inefficient and two copies: User space, kernel space, user space. Linux uses Copy_from_user () and Copy_to_user () to implement these two cross-space copies, where high memory is used, which requires temporary setup/cancellation of page mappings, resulting in a performance penalty. Next is to receive the data cache to be provided by the receiver, the receiver does not know exactly how large the cache is enough, can only open as much space or call the API to receive the message header to obtain

invisible to other processes in the system. 3~4GB is a Linux kernel space that is shared by all the processes and cores of the system. You can view the process memory situation by accessing the relevant files under/proc/{pid}/.If a process contains multiple threads, multiple threads share a process's user-state virtual address space, and the virtual address space contains several areas, mainly in the following areas:1. The code snippet of the current execution file, which is called the text seg

installation nbsp; A.windows under the installation of APC first step: Download Php_apc.dll in HTTP://PECL.PHP.NET/PACKAGE/APC to match the PHP version will php_apc.dll into your ext directory Step two: Let php.ini support the APC extension module. Then open php.ini add: nbsp; Code as follows: Extension=php_apc.dll apc.rfc1867 = on apc.max_file_size = 100M upload_max_filesize = 100M Pos T_max_size = 100M//above parameters can be defined by yourself nbsp; step three: Check to see if you support

, and/DEV/FB is the current default frame buffer device , usually pointing to/dev/fb0. Of course, it is enough to support a display device in an embedded system. The frame buffer device is a standard character device, the main device number is 29, and the secondary device number is 0 to 31. correspond to/dev/fb0-/dev/fb31 respectively. With /DEV/FB, there are several main operations of the application: 1. Read/write (read/write)/DEV/FB: equivalent to a read/write screen buffer. For example, the

access the semaphore. All states of the System V semaphore are contained in the kernel, and their integer identifiers simply tell the kernel to specifically reference that semaphore. ***************************************************************************************POSIX shared memory area memory map file-mmaped file): Shared Memory Area object (shared--mmaped file), opened by the Open function, which is mapped to a file in the current process address space by the