DMA Controller

DMA
DMA Read Operation:
1. DMAC transfers the data from the I/O device into the main memory.
2. DMAC issues an interrupt to the CPU signaling the reception of data.
3. CPU accesses the main memory and processes the received data

DMA Write Operation:
1. CPU writes the data into the main memory.
2. CPU signals the DMAC to start the transaction.
3. DMAC transfers the data from the main memory into the I/O device.

Two important properties of memory systems
Coherence and Consistency

Coherence concerns only one memory location
Consistency concerns apparent ordering for all locations

Coherence defines the behavior of reads and writes to the same memory location.
Consistency defines the behavior of reads and writes with respect to accesses to other memory locations.

HOWTO compile Android Linux on Fedora Core 9

Android - An Open Handset Alliance Project

Compile Linux Kernel

[ ]# mkdir -p /home/android/kernel
[ ]# cd /home/android/kernel
[ ]# wget http://android.googlecode.com/files/linux-2.6.25-android-1.0_r1.tar.gz

[ ]# tar zxvf linux-2.6.25-android-1.0_r1.tar.gz
[ ]# cd kernel.git
[ ]# make goldfish_defconfig

[ ]# CROSS_COMPILE=arm-linux- make

Android SDK
Download from Andriod
[ ]# cd /home/android
[ ]# wget http://dl.google.com/android/android-sdk-linux_x86-1.0_r2.zip
[ ]# unzip android-sdk-linux_x86-1.0_r2.zip

Execute the Emulator
[ ]# cd /home/android
[ ]# ./android-sdk-linux_x86-1.0_r2/tools/emulator -kernel kernel/kernel.git/arch/arm/boot/zImage

Here we go....

Compile the Emulator

[ ]# mkdir -p /home/android/emulator
[ ]# cd /home/android/emulator
[ ]# wget http://android.googlecode.com/files/android-emulator-1.0_r2.tar.bz2

[ ]# tar jxvf android-emulator-1.0_r2.tar.bz2
[ ]# cd android-emulator-20081210

Reference:
1. Android - An Open Handset Alliance Project
2. Google Code

HOWTO lock screen as root on Fedora Core 9

The default screen saver, xscreensaver, does not support this feature, so we need "xlockmore".

[ ]# yum install xlockmore
[ ]# yum install xautolock

[ ]# xlock

HOWTO Install Kermit on Fedora Core 9

Installation
[ ]# mkdir kermit
[ ]# cd kermit
[ ]# wget ftp://kermit.columbia.edu/kermit/archives/cku211.tar.gz
[ ]# tar zxvf cku211.tar.gz
[ ]# make linux
[ ]# make install

User Manual
[ ]# kermit -l /dev/ttyS0 -b 9600 -c

Reference:
1. http://www.columbia.edu/kermit