Symbian Developer

Symbian Developer

Notification Chains

Notification Chains

For Network subsystem: example code
For System reboot: example code

Gigabit Ethernet Controller

Pseudo Linux Network Device Driver (tar.gz)

Another Beginning

Timestamp

Linux Timer

Low-Resolution Timer

Time Stamp: Jiffy

High-Resolution Timer

Time Stamp: Nanosecond
Clock Base: (1) Monotonic Clock (2) Real Time Clock

Dynamic Tick

Power Management

Objects for Time Management
Clock Sources
Clock Event Devices
Tick Devices

Linux IO Scheduler

The IO Schedulers

No-op Scheduler

This scheduler only implements request merging.

Anticipatory IO Scheduler (AS)

This scheduler implements request merging, a one-way elevator, read and write request batching, and attempts some anticipatory reads by holding off a bit after a read batch if it thinks a user is going to ask for more data.

This is optimised for the single disk systems.

Deadline Scheduler

The scheduler implements request merging, a one-way elevator, and imposes a deadline on all operations to prevent resource starvation.

Complete Fair Queueing Scheduler (CFQ)

The scheduler implements both request merging and the elevator, and attempts to give all users of a particular device the same number of IO requests over a particular time interval.

References:
Linux I/O Schedulers

CPU affinity

Soft CPU affinity
Processes do not frequently migrate between processors.
Hard CPU affinity
Processes run on processors you specify.

The Linux kernel API:

To alter the bitmask
   sched_set_affinity()

To view the current bitmask
   sched_get_affinity()

Memory Benchmark Test

Memory Performance

stream

STREAM

void
STREAM_Copy (double *source, double *destination, int size) {
   int j;
   size=size/8;
   for (j=0; j < size; j++)
      source[j] = destination[j];
}

Byte Copy

void
byte_copy (char *source, char *destination, int size) {
   int j;
   for (j=0; j < size; j++)
      source[j] = destination[j];
}

mem_bench



Bandwidth (x86) (0.15, 32bits) (0.16, 64bits)

CPU Benchmark Test

CPU Core

nbench

Floating-Point

fp_bench

CPU Utilization

sysstat

Storage Performance Test

Disk I/O Performance

CrystalDiskMark (2.2)

datamark (0.0.4)

dd (coreutils)

[ ]# dd if=/dev/hda1 of=/dev/hdb1 bs=4k conv=noerror,sync

dd_rescue

[ ]# dd_rescue /dev/zero /media/disk/zero2G -m 2G

File System Performance

IOzone 3

x86 version (bin) (src)
ARM version (bin) (src)

Iometer

Bonnie++

Misc:
sar - system activity report
   Example: http://www.thegeekstuff.com/2011/03/sar-examples/
iperf - perform network throughput tests
hdparm - to test local disk performance of any bricks
dbench - Measure disk throughput for simulated netbench run
iozone - Filesystem Benchmark
htop - interactive process viewer
vnstat - a console-based network traffic monitor
iftop - display bandwidth usage on an interface by host

HOWTO Build Android Platform on Fedora Core 9

The final file structure looks like that

/home/android/
`-- mydroid
|-- bionic
|-- bootable
|-- build
|-- dalvik
|-- development
|-- external
|-- frameworks
|-- hardware
|-- packages
|-- prebuilt
`-- system


=========================================================

Download Android Source Code

[ ]# wget http://android.git.kernel.org/repo
[ ]# chmod +x repo
[ ]# mv repo /usr/bin

[ ]# mkdir -p /home/android/mydroid
[ ]# cd /home/android/mydroid
[ ]# repo init -u git://android.git.kernel.org/platform/manifest.git

gpg: keyring `/root/.repoconfig/gnupg/secring.gpg' created
gpg: keyring `/root/.repoconfig/gnupg/pubring.gpg' created
gpg: /root/.repoconfig/gnupg/trustdb.gpg: trustdb created
gpg: key 920F5C65: public key "Repo Maintainer "
imported
gpg: Total number processed: 1
gpg: imported: 1

Getting repo ...
from git://android.git.kernel.org/tools/repo.git
warning: no common commits
remote: Counting objects: 906, done.
remote: Compressing objects: 100% (404/404), done.
remote: Total 906 (delta 569), reused 785 (delta 482)
Receiving objects: 100% (906/906), 277.53 KiB | 142 KiB/s, done.
Resolving deltas: 100% (569/569), done.
From git://android.git.kernel.org/tools/repo
* [new branch] master -> origin/master
* [new branch] stable -> origin/stable
* [new tag] v1.6.8.7 -> v1.6.8.7
From git://android.git.kernel.org/tools/repo
* [new tag] v1.0 -> v1.0
* [new tag] v1.0.1 -> v1.0.1
* [new tag] v1.0.2 -> v1.0.2
* [new tag] v1.0.3 -> v1.0.3
* [new tag] v1.0.4 -> v1.0.4
* [new tag] v1.0.5 -> v1.0.5
* [new tag] v1.0.6 -> v1.0.6
* [new tag] v1.0.7 -> v1.0.7
* [new tag] v1.0.8 -> v1.0.8
* [new tag] v1.0.9 -> v1.0.9
* [new tag] v1.1 -> v1.1
* [new tag] v1.2 -> v1.2
* [new tag] v1.3 -> v1.3
* [new tag] v1.3.1 -> v1.3.1
* [new tag] v1.3.2 -> v1.3.2
* [new tag] v1.4 -> v1.4
* [new tag] v1.4.1 -> v1.4.1
* [new tag] v1.4.2 -> v1.4.2
* [new tag] v1.4.3 -> v1.4.3
* [new tag] v1.4.4 -> v1.4.4
* [new tag] v1.5 -> v1.5
* [new tag] v1.5.1 -> v1.5.1
* [new tag] v1.6 -> v1.6
* [new tag] v1.6.1 -> v1.6.1
* [new tag] v1.6.2 -> v1.6.2
* [new tag] v1.6.3 -> v1.6.3
* [new tag] v1.6.4 -> v1.6.4
* [new tag] v1.6.5 -> v1.6.5
* [new tag] v1.6.6 -> v1.6.6
* [new tag] v1.6.7 -> v1.6.7
* [new tag] v1.6.7.1 -> v1.6.7.1
* [new tag] v1.6.7.2 -> v1.6.7.2
* [new tag] v1.6.7.3 -> v1.6.7.3
* [new tag] v1.6.7.4 -> v1.6.7.4
* [new tag] v1.6.7.5 -> v1.6.7.5
* [new tag] v1.6.8 -> v1.6.8
* [new tag] v1.6.8.1 -> v1.6.8.1
* [new tag] v1.6.8.2 -> v1.6.8.2
* [new tag] v1.6.8.3 -> v1.6.8.3
* [new tag] v1.6.8.4 -> v1.6.8.4
* [new tag] v1.6.8.5 -> v1.6.8.5
* [new tag] v1.6.8.6 -> v1.6.8.6
Getting manifest ...
from git://android.git.kernel.org/platform/manifest.git
warning: no common commits
remote: Counting objects: 116, done.
remote: Compressing objects: 100% (45/45), done.
remote: Total 116 (delta 39), reused 107 (delta 36)
Receiving objects: 100% (116/116), 29.54 KiB, done.
Resolving deltas: 100% (39/39), done.
From git://android.git.kernel.org/platform/manifest
* [new branch] android-1.5 -> origin/android-1.5
* [new branch] android-1.5r2 -> origin/android-1.5r2
* [new branch] android-sdk-1.5-pre -> origin/android-sdk-1.5-pre
* [new branch] android-sdk-1.5_r1 -> origin/android-sdk-1.5_r1
* [new branch] cdma-import -> origin/cdma-import
* [new branch] cupcake -> origin/cupcake
* [new branch] donut -> origin/donut
* [new branch] master -> origin/master
* [new branch] release-1.0 -> origin/release-1.0
* [new tag] android-1.5 -> android-1.5
* [new tag] android-1.5r2 -> android-1.5r2
* [new tag] android-sdk-1.5-pre -> android-sdk-1.5-pre
* [new tag] android-sdk-1.5_r1 -> android-sdk-1.5_r1
From git://android.git.kernel.org/platform/manifest
* [new tag] android-1.0 -> android-1.0

Your Name [ ]: scott
Your Email [ ]: scott.shu@gmail.com

Your identity is: scott
is this correct [yes/no]? yes

Testing colorized output (for 'repo diff', 'repo status'):
black red green yellow blue magenta cyan white
bold dim ul reverse
Enable color display in this user account (y/n)? y

[ ]# repo sync
... skip ...
... skip ... checkout 1.9G in 22 minutes
[ ]#

Install some tools before build "manifest"
[ ]# yum install java-1.6.0-openjdk-devel
[ ]# yum install gperf

Make it

Reference:
http://source.android.com/download/using-repo

HOWTO Install Android SDK 1.5.r2 on Fedora Core 9

The final file structure looks like that

/home/android/
|-- android-kernel
| `-- kernel
|-- android-sdk
| `-- android-sdk-linux_x86-1.5_r2

=========================================================

Download Android 1.5 SDK, Release 2
[ ]# mkdir -p /home/android/android-sdk
[ ]# cd /home/android/android-sdk
[ ]# wget http://developer.android.com/sdk/download.html?v=android-sdk-linux_x86-1.5_r2.zip
[ ]# unzip android-sdk-linux_x86-1.5_r2.zip

Linux Kernel for Android
[ ]# mkdir -p /home/android/android-kernel
[ ]# cd /home/android/android-kernel
[ ]# git clone git://android.kernel.org/kernel/common.git kernel
[ ]# cd kernel

[ ]# git branch goldfish origin/android-goldfish-2.6.27
[ ]# git checkout goldfish

[ ]# make ARCH=arm CROSS_COMPILE=arm-linux- goldfish_defconfig
[ ]# make ARCH=arm CROSS_COMPILE=arm-linux- menuconfig
[ ]# make ARCH=arm CROSS_COMPILE=arm-linux- zImage

Switched to branch "goldfish-2.6.29"
[ ]# git branch goldfish-2.6.29 origin/android-goldfish-2.6.29
[ ]# git checkout goldfish-2.6.29

To see a list of existing branches
[ ]# git branch
android-2.6.27
goldfish
* goldfish-2.6.29

Android Emulator

Create Android Virtual Device
[ ]# android-sdk/android-sdk-linux_x86-1.5_r2/tools/android create avd -n foo -t 3
Created AVD 'foo' based on Google APIs (Google Inc.)

Run the emulator
[ ]# android-sdk/android-sdk-linux_x86-1.5_r2/tools/emulator @foo -kernel android-kernel/kernel/arch/arm/boot/zImage

Delete the Android Virtual Device
[ ]# android-sdk/android-sdk-linux_x86-1.5_r2/tools/android delete avd -n foo

Endianness

LE: Little-endian

BE-8: Byte-Invariant Big-endian

BE-32: Word-Invariant Big-endian

The differences between BE-32 and BE-8 data buses are:
• In a BE-32 system, the representation of a 32-bit Word access is
the same between a BE-32 access and a LE access to the same word address.
However, the representation of the byte (and half-word) accesses on the bus is
different.

• In a BE-8 system, the representation of a byte access is the same
between a BE-8 access and a LE access to the same byte address. However, the
representation of the word (and half-word) accesses on the bus is different.

Android Development Environment

Linux Kernel Reading Book List

1. Professional Linux Kernel Architecture (PDF)


This book is focus on kernel 2.6.24 ~ 2.6.26.
2.

Android Reading List

1. Hello, Android: Introducing Google's Mobile Development Platform
2. Android Application Development
3. Unlocking Android (PDF)
4. Professional Android Application Development (PDF)
5. Android Essentials (PDF)
6. Beginning Android (PDF)
7. Pro Android (PDF)
8. Androd Programmer Guide (PDF)
9. The Busy Coder's Guide to Android Development ()
10.


Related Blog:
http://scottshulinux.blogspot.com/2009/01/howto-compile-android-linux-on-fedora.html

Eclipse

Embedded Linux development using Eclipse
(PDF)



Eclipse Distro + Subversive Team Provider
Free download

Linux Kernel Stuff

Linux Kernel Makefiles
http://www.ravnborg.org/kbuild/makefiles.html

Linux Test Tools

Linux Test Tools

http://ltp.sourceforge.net/tooltable.php

Linux Memory Test

Memtester

1) Random value
2) XOR comparison
3) SUB comparison
4) MUL comparison
5) DIV comparison
6) OR comparison
7) AND comparison
8) Sequential Increment
9) Block Sequential
10) Solid Bits
11) Bit Flip
12) Checkerboard
13) Walking Ones / Walking Zeroes

The walking "1"'s (for a byte wide memory) involves writing a binary value "00000001" into the first location in read/write memory. The value is then shifted one position to the left so that the binary value is "00000010". This value is written to the next location in memory. When the "1" is left shifted out of the 8-bit value, the value "00000001" is reused and the left-shifting begins again from there. This pattern of left-shift by one bit then writing the new value to next memory location is repeated until all of the memory is written.

Once all memory is written then the memory is read location by location and compared to the left-shifted pattern originally written.

The walking "0"'s is the same algorithm with the exception that the pattern used begins with a "11111110" written to the first memory location and "11111101" is written to the second location.

This test is intended to uncover data or address bus problems both internal to the memory device as well as external.

14) Bit Spread
A Bit Spread test, to help catch inter-bit dependencies within a word when a 0 bit is caught between two 1 bits, or vice versa.

LMBench

CacheBench

1) memset() from the C library
2) memcpy() from the C library
3) Cache Read
4) Cache Write
5) Cache Read/Modify/Write

STREAM

U-boot Memory Test

Other Test Algorithm:

Self Address

Write the address of the memory to the memory.

March C- Solid Bits

It consists of writing an all-0’s pattern (and all-1’s pattern), then reading all the cells.

March C- Checkerboard

Writes 1’s and 0’s into alternate memory locations in a checkerboard pattern. Wait for several seconds and read. Repeat for complementary patterns.

Walking Ones Left

Walking Ones Right

Walking Zeros Left

Walking Zeros Right

Reference:
1. The March10N/MarchC memory test
2. Fast Accurate Memory Test Suite

Cache

Write-through

Write-back

The value kept in the backing store should be up-to-
date with any changes made to the version stored
in the cache, but only to the point that it is possible
to ensure that any read requests to the version in the
backing store (e.g., from another processor) return
the most recently written value stored in the cache.

Two typical mechanisms used in general-purpose
caches to effect this responsibility are write-back and
write-through policies. When writing to a cache, the
backing store is implicitly updated, but when? Two
obvious choices are immediately and later; the first
is write-through, and the second is write back.

outer_inv - /* invalidate only */
outer_clean - /* writeback only */
outer_flush - /* writeback and invalidate */

MMC/SD/SDIO on Linux

MMC/SD/SDIO Device Driver
Download patch

How to use MMC/SD card

[ ]# cat /proc/partitions

[ ]# mknod /dev/mmcblk0 b 179 0
[ ]# mknod /dev/mmcblk0p1 b 179 1

[ ]# mount /dev/mmcblk0p1 /mnt

RTC on Linux

Real Time Clock

RTC Device Driver
Download patch

RTC Utility

[ ]# mknod /dev/rtc0 c 254 0

[ ]# date 2009.05.20-12:34:56

[ ]# hwclock -w

[ ]# cat /proc/driver/rtc

[ ]#

IP Calculator

IP Calculator

ipcalc takes an IP address and netmask and calculates the resulting broadcast, network, Cisco wildcard mask, and host range. By giving a second netmask, you can design subnets and supernets. It is also intended to be a teaching tool and presents the subnetting results as easy-to-understand binary values.

Watchdog Timer

Hardware Watchdog Driver

Userspace Watchdog Program

Software Watchdog

FAT File System

The First Block (512 Bytes)

MMC/SD on u-boot

Card Information


Load bootpImage from MMC/SD Card

u-boot # mmcinfo
mmc_init
version_2 = 1
Manufacturer ID: 03
OEM/Application ID: 5344
Product name: SD08G
Product Revision: 8.0
Product Serial Number: 59007
Manufacturing Date: 08/12
MMC/SD RCA = 0x8FE4
CSD data: 400e0032 5b590000 3cdc7f80 0a404000
CSD structure version: 1
Card command classes: 5b5
Read block length: 512
Does not support partial reads
Write block length: 512
Does not support partial writes
Does not support group WP
Card capacity: 7977472 Kbytes
File format: 0/0
Write protection:

u-boot # fatinfo mmc 0
Interface: MMC
Device 0: Vendor: Man 035344 Snr 0000e67f Rev: 8 0 Prod: SD08G
Type: Removable Hard Disk
Capacity: 7790.5 MB = 7.6 GB (15954944 x 512)
Partition 1: Filesystem: FAT32 "NO NAME "

u-boot # fatls mmc 0
3745704 bootpimage

1 file(s), 0 dir(s)

u-boot # fatload mmc 0 0x1000000 bootpImage
reading bootpImage

3745704 bytes read

u-boot # go 0x1000000

Download Patch

Reference:
1. Simplified Physical Layer Spec. (Version 2.00)
2. Simplified SD Host Controller Spec. (Version 2.00)
3. Simplified SDIO Card Spec. (Version 2.00)

Linux SMP Kernel boot-up messages on ARM11 MPCore based Platform

Linux version 2.6.27-arm1 (scott.shu@gmail.com) (gcc version 4.3.2 (G9
CPU: ARMv6-compatible processor [410fb020] revision 0 (ARMv7), cr=00c5387f
Machine: S---- ARM11 MPCore
Memory policy: ECC disabled, Data cache writeback
On node 0 totalpages: 65536
free_area_init_node: node 0, pgdat c022a8c0, node_mem_map c0261000
DMA zone: 65024 pages, LIFO batch:15
CPU0: D VIPT write-back cache
CPU0: I cache: 32768 bytes, associativity 4, 32 byte lines, 256 sets
CPU0: D cache: 32768 bytes, associativity 4, 32 byte lines, 256 sets
Built 1 zonelists in Zone order, mobility grouping on. Total pages: 65024
Kernel command line: root=/dev/ram0 rw init=/linuxrc mem=256M console=ttyS0,3840
PID hash table entries: 1024 (order: 10, 4096 bytes)
Console: colour dummy device 80x30
console [ttyS0] enabled
Dentry cache hash table entries: 32768 (order: 5, 131072 bytes)
Inode-cache hash table entries: 16384 (order: 4, 65536 bytes)
Memory: 256MB = 256MB total
Memory: 254592KB available (2008K code, 281K data, 104K init)
Calibrating delay loop... 104.24 BogoMIPS (lpj=521216)
Mount-cache hash table entries: 512
CPU: Testing write buffer coherency: ok
CNS3000: no. of cores (4) greater than configured maximum of 2 - clipping
Calibrating local timer... 131.10MHz.
CPU1: Booted secondary processor
CPU1: D VIPT write-back cache
CPU1: I cache: 32768 bytes, associativity 4, 32 byte lines, 256 sets
CPU1: D cache: 32768 bytes, associativity 4, 32 byte lines, 256 sets
Calibrating delay loop... 104.65 BogoMIPS (lpj=523264)
Brought up 2 CPUs
SMP: Total of 2 processors activated (208.89 BogoMIPS).
CPU0 attaching sched-domain:
domain 0: span 0-1 level CPU
groups: 0 1
CPU1 attaching sched-domain:
domain 0: span 0-1 level CPU
groups: 1 0
net_namespace: 596 bytes
NET: Registered protocol family 16
NET: Registered protocol family 2
IP route cache hash table entries: 2048 (order: 1, 8192 bytes)
TCP established hash table entries: 8192 (order: 4, 65536 bytes)
TCP bind hash table entries: 8192 (order: 4, 65536 bytes)
TCP: Hash tables configured (established 8192 bind 8192)
TCP reno registered
NET: Registered protocol family 1
checking if image is initramfs...it isn't (no cpio magic); looks like an initrd
Freeing initrd memory: 2571K
JFFS2 version 2.2. (NAND) © 2001-2006 Red Hat, Inc.
msgmni has been set to 502
io scheduler noop registered
io scheduler deadline registered (default)
Serial: 8250/16550 driver1 ports, IRQ sharing disabled
serial8250: ttyS0 at MMIO 0x78000000 (irq = 37) is a 16550A
brd: module loaded
loop: module loaded
TCP cubic registered
NET: Registered protocol family 17
Bridge firewalling registered
802.1Q VLAN Support v1.8 Ben Greear
All bugs added by David S. Miller
VFP support v0.3: implementor 41 architecture 1 part 20 variant b rev 3
RAMDISK: Compressed image found at block 0
VFS: Mounted root (ext2 filesystem).
Freeing init memory: 104K

# cat /proc/interrupts
CPU0 CPU1
32: 50 0 GIC Timer Tick
37: 4542 0 GIC serial
IPI: 334 493
LOC: 25087 25099
Err: 0

# cat /proc/cpuinfo
Processor : ARMv6-compatible processor rev 0 (v6l)
processor : 0
BogoMIPS : 104.24
processor : 1
BogoMIPS : 104.65
Features : swp half thumb fastmult vfp edsp java
CPU implementer : 0x41
CPU architecture: 7
CPU variant : 0x0
CPU part : 0xb02
CPU revision : 0
Cache type : write-back
Cache clean : cp15 c7 ops
Cache lockdown : format C
Cache format : Harvard
I size : 32768
I assoc : 4
I line length : 32
I sets : 256
D size : 32768
D assoc : 4
D line length : 32
D sets : 256
Hardware : S---- ARM11 MPCore
Revision : 0000
Serial : 0000000000000000

Floating Point on Linux

Hardware FPU
VFP - VectorFloating Point

Software FPE (Floating Point Emulation)
NWFPE - NetWinder Floating Point Emulator

FASTFPE - FAST Floating Point Emulator

Performance:

Test program: fp_bench (fp_bench.tar.gz)

Endianness

• Little-endian

• Big-endian

LCD Driver for u-boot and Linux

LCD Controller:
LCD Panel:

LCD Driver for u-boot



LCD Driver for Linux

Linux Kernel boot-up messages on ARM11 MPCore based Platform

Today is the day I successfully port Linux kernel 2.6.27.4 to our own ARM11MPCore based SoC.

Linux version 2.6.27-arm1 (scott.shu@gmail.com) (gcc version 4.1.2)
#3 PREEMPT Tue Feb 10 05:
38:07 CST 2009
CPU: ARMv6-compatible processor [410fb020] revision 0 (ARMv7), cr=00c5387f
Machine: S----- ARM11 MPCore
Memory policy: ECC disabled, Data cache writeback
On node 0 totalpages: 65536
free_area_init_node: node 0, pgdat c021fc50, node_mem_map c0255000
DMA zone: 65024 pages, LIFO batch:15
CPU0: D VIPT write-back cache
CPU0: I cache: 32768 bytes, associativity 4, 32 byte lines, 256 sets
CPU0: D cache: 32768 bytes, associativity 4, 32 byte lines, 256 sets
Built 1 zonelists in Zone order, mobility grouping on. Total pages: 65024
Kernel command line: root=/dev/ram0 rw init=/linuxrc mem=256M
console=ttyS0,38400
PID hash table entries: 1024 (order: 10, 4096 bytes)
Console: colour dummy device 80x30
console [ttyS0] enabled
Dentry cache hash table entries: 32768 (order: 5, 131072 bytes)
Inode-cache hash table entries: 16384 (order: 4, 65536 bytes)
Memory: 256MB = 256MB total
Memory: 254848KB available (1980K code, 273K data, 88K init)
SLUB: Genslabs=12, HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
Calibrating delay loop... 73.11 BogoMIPS (lpj=365568)
Mount-cache hash table entries: 512
CPU: Testing write buffer coherency: ok
net_namespace: 288 bytes
NET: Registered protocol family 16
NET: Registered protocol family 2
IP route cache hash table entries: 2048 (order: 1, 8192 bytes)
TCP established hash table entries: 8192 (order: 4, 65536 bytes)
TCP bind hash table entries: 8192 (order: 3, 32768 bytes)
TCP: Hash tables configured (established 8192 bind 8192)
TCP reno registered
NET: Registered protocol family 1
checking if image is initramfs...it isn't (no cpio magic); looks like an
initrd
Freeing initrd memory: 2379K
JFFS2 version 2.2. (NAND) i??Ac 2001-2006 Red Hat, Inc.
msgmni has been set to 502
io scheduler noop registered
io scheduler deadline registered (default)
Serial: 8250/16550 driver1 ports, IRQ sharing disabled
serial8250: ttyS0 at MMIO 0x78000000 (irq = 37) is a 16550A
brd: module loaded
loop: module loaded
TCP cubic registered
NET: Registered protocol family 17
VFP support v0.3: implementor 41 architecture 1 part 20 variant b rev 3
RAMDISK: Compressed image found at block 0
VFS: Mounted root (ext2 filesystem).
Freeing init memory: 88K
#
#

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