September 2010
16 posts
1 tag
Some examples of packages
initscripts - Contains basic system startup and shutdown scripts.
apache - Implements the popular Apache web server
telnet-server - Contains files necessary to implement telnet server functionality, which allows you to establish Telnet sessions to your embedded targets.
glibc - Standard C library
busybox - Compact versions of dozens of popular command line utilities commonly found on...
MMU
Memory Management Units (MMU) whose purpose is to enable an operating system to exercise a high degree of management and control over its address space and the address space it allocates to processes. This control comes in two primary forms: access right and memory translation. Access rights allow an operating system to assign specific memory-access privileges to specific tasks. Mmeory...
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.vdi →
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Flash Usage
The bootloader is often placed in the top or bottom of the flash memory array. Following the bootloader, space is allocated for the Linux kernel image and ramdisk file system image, which holds the root file system. Typically, the Linux kernel and ramdisk file system images are compressed, and the bootloader handles the decompression task during the boot cycle.
1 tag
Kernel Initialization
When the kernel begins execution, it spews out numerous status messages during its rather comprehensive boot process. In upper figure, it reproduces the last several lines of output before the login prompt.
Shortly before issuing a login prompt on our serial terminal, Linux mounts a root file system. In the figure, Linux goes through the steps required to mount its root file system remotely...
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Starting the Target Board
When power is first applied, a bootloader supplied with your target board takes immediate control of the processor. It performs some very low-level hardware initialization, including processor and memory setup, initialization of the UART controlling the serial port, and initialization of the Ethernet controller.
As the upper figure, when power is applied to the Yosemite board, the PowerPC...
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minicom
A serial terminal program is used to communicate with the target board. Minicom is one of the most commonly used serial terminal applications.
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BIOS vs Bootloader
The BIOS is a complex set of system-configuration software routines that have knowledge of the low-level details of the hardware architecture. Its primary responsibility is to initialize the hardware, especially the memory subsystem, and load an operating system from the PC’s hard drive.
A bootloader is the software program that performs on power-up as follows:
Initializes critical...
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Minimul File System
|
| —- bin
| | —- busybox
| ’ —- sh -> busybox
| —- dev
| ’ —- console
| —- etc
| ’ —- init.d
| ’ —- rcS
’ —- lib
| —- ld-2.3.2.so
| —- ld-linux.so.2 -> ld-2.3.2.so
| —- libc-2.3.2.so
’ —- libc.so.6 ->...
1 tag
Top-level directories
bin: Binary executables, usable by all users on the system
dev: Device nodes
etc: Local system-configuration files
lib: System libraries, such as the standard C library and many others
sbin: Binary executables usually reserved for superuser accounts on the system
usr: A secondary file system hierarchy for application programs, usually read-only
var: Contains variable files, such as...
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About NFS setting
https://help.ubuntu.com/community/Installation/OnNFSDrive
http://blog.youck.org/
The one
And I realized that I do have a faith. Faith in myself. Faith that one day I’ll meet someone who will be sure that I was the one.
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Enable usb to serial adapter
1. dmesg
After plugging in the device, first check the hardware messages to see the device was detected:
2. lsusb
Figure out the device vendor number and product number to tell the usbserial driver.
Unplug the device, then run lsusb.
Plug the device and type lsusb
3. Load up the driver for this device: sudo modprobe usbserial vendor=0x2478 product=0x2008
4. dmesg
Check dmesg again...
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Embedded Development Environment
The Network File System (NFS) was developed to allow machines to mount a disk partition on a remote machine as if it were a local disk. It allows for fast, seamless sharing of files across a network.
人生，分分合合
刚刚和LY打电话，听说wwm离开了公司，离开了上海，回老家做生意了。组里也走了一半以上的人，突然让我特别感慨，两年，我离开了又回了公司。两年，不长也不短。有些事情过去了，永远只能在回忆里温习，想着走之前三个人坐在wwm的电驴上，大声笑，大声叫。想着，他唱歌害羞，想着说好回国的时候再一起吃饭，却因为时间没有遇上，或许就此不会再见。想着那时候，我说我不会烧菜，他认真的录像教我烧油焖茄子，突然觉得很温暖。
温暖，永远都是在记忆里。