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Build stress-ng for ARM

From the README file, some packages are needed to build stress-ng:
* libaio-dev
* libapparmor-dev
* libattr1-dev
* libbsd-dev
* libcap-dev
* libgcrypt11-dev
* libkeyutils-dev
* libsctp-dev
* zlib1g-dev

Since I am building stress-ng for testing in-house SoC, not all features are necessary to be enabled to test. Here is the steps I built.

1. Grab sources tarballs from https://packages.debian.org/sid/libaio-dev
These two tarballs are needed:
libaio_0.3.110.orig.tar.gz
libaio_0.3.110-5.debian.tar.xz

$ tar axf libaio_0.3.110.orig.tar.gz
$ tar axf libaio_0.3.110-5.debian.tar.xz
$ cd libaio-0.3.110/
$ for i in `cat ../debian/patches/series`; do patch -p1 < ../debian/patches/${i}; done
$ CC=arm-linux-gnueabihf-gcc CFLAGS=-mcpu=cortex-a9 make prefix=${HOME}/toolchain/arm-sysroot install

If the build failed because of some re-definition of __NR_io_setup, ... etc., modify
libaio-0.3.110/src/syscall-arm.h
to be
#ifndef __NR_io_setup
#define __NR_io_setup                   (__NR_SYSCALL_BASE+243)
#endif
#ifndef __NR_io_destroy
#define __NR_io_destroy                 (__NR_SYSCALL_BASE+244)
#endif
#ifndef __NR_io_getevents
#define __NR_io_getevents               (__NR_SYSCALL_BASE+245)
#endif
#ifndef __NR_io_submit
#define __NR_io_submit                  (__NR_SYSCALL_BASE+246)
#endif
#ifndef __NR_io_cancel
#define __NR_io_cancel                  (__NR_SYSCALL_BASE+247)
#endif

2. Grab source tarball from https://packages.debian.org/sid/zlib1g-dev

$ tar axf zlib_1.2.8.dfsg.orig.tar.gz
$ cd zlib-1.2.8/
$ CC=arm-linux-gnueabihf-gcc CFLAGS="-mcpu=cortex-a9 -O3" ./configure --prefix=${HOME}/toolchain/arm-sysroot
$ make install

3. Build stress-ng

$ tar axf stress-ng-0.09.15.tar.xz
$ cd stress-ng-0.09.15/
$ CC=arm-linux-gnueabihf-gcc \
> CFLAGS="-pthread -mcpu=cortex-a9 -I${HOME}/toolchain/arm-sysroot/include -L${HOME}/toolchain/arm-sysroot/lib" \
> STATIC=1 make ARCH=arm

Copy the generated stress-ng to the board and run

# ./stress-ng  --metrics-brief --verbose --timeout 5m --all 1

Change the thresholds of battery charging

In Ubuntu, it is possible to control when to start and stop battery charging based on capacity levels.

sudo apt-get install tp-smapi-dkms
sudo modprobe tp_smapi

if [ -e /sys/devices/platform/smapi ]
then
    cd /sys/devices/platform/smapi/
    for i in BAT?
    do
        cd $i
        echo 40 | sudo tee start_charge_thresh
        echo 80 | sudo tee stop_charge_thresh
        cd ..
    done
fi

Ubuntu 16.04 安裝 Rime 輸入法

1. Enable support for Chinese

1. Launch "System Settings"
2. Click "Install / Remove Languages..."
3. Add "Chinese (traditional)"
4. Log out and log in again
5. Install rime by "sudo apt-get install fcitx-rime"
6. Launch "System Settings"
7. Select "fcitx" for Keyboard input method system
8. Log out and log in again

ref: http://www.pinyinjoe.com/linux/ubuntu-12-chinese-setup.htm

2. Select rime

1. Click the keyboard selection icon on the top-right corner of the screen
2. Select "Text Entry Settings..."
3. Click the "+" button on the left-down corner to add an input source to use
4. Search for "rime" and add it

ref: http://www.pinyinjoe.com/linux/ubuntu-10-chinese-input-pinyin-chewing.htm

File system random write test

wtest()
{
    val=$(( ($RANDOM % 10000 ) + 1 ))
    name=$val
    echo $name
    while [ $val != 0 ]
    do
        echo $val >> $name
        val=$(( $val - 1 ))
    done
    rm $name
}

md5sum files in directories and check

job()
{
    while true
    do
        find bin/ etc/ lib/ sbin/ selinux/ system/ usr/ -type f -exec md5sum \{\} \; > $name
        cal=`md5sum $name | awk -e "{print \\$1}"`
        if [ $cal != 207c55670e306a3a06ea87456e0859da ]
        then
            echo Mismatch
            break
        fi
        sleep $(( ($RANDOM % 20 )  + 1 ))
    done
}

Flush cache

nocache()
{
    while true
    do
        sync
        echo 3 > /proc/sys/vm/drop_caches
        sleep $(( ($RANDOM % 20 )  + 1 ))
    done
}

Turn Off All CPUs except the 0

for i in `busybox seq 1 9`

do

    if [ -e /sys/devices/system/cpu/cpu${i}/online ]

    then

        echo 0 〉 /sys/devices/system/cpu/cpu${i}/online

    fi

done

Set the DD-WRT based D-Link DIR-300 ver. B as a Repeater Bridge

Original link here: http://jgiam.com/2012/07/06/setting-up-a-repeater-bridge-with-dd-wrt-and-d-link-dir-600/wp-admin/install.php

Here are the steps I did (adapted from the DD-WRT Wiki). My primary router is configured with WPA2 AES. The secondary router is running DD-WRT build 14311. The latest build in the DD-WRT router database, build 14896, is buggy.

• Restore Factory Defaults on Secondary (DD-WRT) Router
• Connect your computer to the secondary router via wired LAN port.
• Open the address http://192.168.1.1 in your web browser. Newer versions of DD-WRT will require you to set a password before you can continue.
• Open the Wireless -> Basic Settings tab
  • Physical Interface Section
    • Wireless Mode : Repeater Bridge
    • Wireless Network Mode : Must Match Primary Router
    • Wireless Network Name(SSID) : Must Match Primary Router exactly including exact case- Make sure you spell this correctly
    • Wireless Channel : Must Match Primary Router (This will disappear once you put it in RB mode, and isn’t needed)
    • Wireless SSID Broadcast : Enable
    • Network Configuration : Bridged
  • Save
• Open the Wireless -> Wireless Security tab
  • Physical Interface Section
    • Security Mode : Must Match Primary Router and DD-wrt only works reliably with WEP or WPA2-AES
    • WPA Algorithms : Must Match Primary Router
    • WPA Shared Key : Must Match Primary Router
    • Key Renewal Interval (in seconds) : Leave default
  • Save
• Open the Setup -> Basic Setup tab
  • Connection Type will be: Disabled
  • Set STP for Disabled (Enabled sometimes can cause connection problems) redhawk
  • IP Address : 192.168.1.2 (Assuming Primary Router IP is 192.168.1.1)
  • Mask : 255.255.255.0
  • Gateway: 192.168.1.1 (again assuming Primary Router IP is 192.168.1.1)
  • DHCP Server: Disable
  • Local DNS: 192.168.1.1 (if IP of Primary Router is 192.168.1.1)
  • Assign WAN Port to Switch : Optionally enable this to use the WAN port as another LAN port.
  • Save
• Open Setup -> Advanced Routing tab
  • Set Operating mode to “Router”
  • Save
• Open Services
  • Disable Dnsmasq
  • Save
• Open the Security -> Firewall tab
  • Uncheck all boxes…except Filter Multicast
  • Disable SPI firewall
  • APPLY Settings
• Reboot the router.

Build emacs 24.3 from source for Ubuntu 12.04

sudo apt-get install build-essential libxpm-dev libgif-dev libtiff4-dev libjpeg-dev libgtk-3-dev xaw3dg-dev libdbus-glib-1-dev libgpmg1-dev libgnome2-dev libotf-dev libncurses5-dev libm17n-dev
tar axf emacs-24.3.tar.xz
mkdir bld
cd bld
../emacs-24.3/configure --prefix=/home/sun409/tools --without-x --without-sound --without-pop
make
make install

Terminal emulator settings

Color
Blue: 0, 40, 255
Light blue: 0, 128, 255
Max column: 220
Scroll to bottom only when key pressed.
Terminal
Xterm
ANSI color
Scroll back 32000
Terminal type: xterm-256color
Back space sends delete
Emacs
ALT
Escape
Log
File name: %S-%Y%M%D-%h.log
Custom keys
S-PageUp: \033[1;2I
S-PageDown: \033[1;2G
S-Home: \033[1;2H
S-End: \033[1;2F
S-Up: \033[1;2A
S-Down: \033[1;2B
S-Right: \033[1;2C
S-Left: \033[1;2D
A-g: \033g
A-S-Up: \033[1;6A
A-S-Down: \033[1;6B
A-S-Right: \033[1;6C
A-S-Left: \033[1;6D

Linux kernel bigphysarea

最近在看怎麼在 Linux kernel 裡管理大塊的連續記憶體，查到這個：
http://lkml.indiana.edu/hypermail/linux/kernel/0503.2/0405.html

“We don't tend to change code for out-of-tree users, either.”

對呀，所有的這類的需求都是為了自家的 driver，你不放進 kernel 人家自然就不想支援。
附上找到的最近的 bigphysarea patch：
http://www.feise.com/~jfeise/Downloads/zr36120/

CentOS ssh login without input password by using PuTTY

1. Use puttygen.exe to generate the public key and private key. Click the "Generate" button.

 2. Move your mouse to add randomness.

3. [IMPORTANT] Copy the selected text and append it to the file .ssh/authorized_keys on the Linux server.

4. Click the "Save private key" button to save your private key. I save it to the directory where PuTTY is installed and named it id_rsa.ppk

5. Use the just created private key.

6. You still have to log in with your password the last time. Set SELinux file security contexts.

  sudo restorecon -R -v /home/$ACCOUNT/.ssh 

7. Happy SSH!

Enlarge a file system in an LVM

Suppose /dev/sdb is the newly added disc. The original volume group is vg_dvd01. The logical volume to be enlarged is lv_home.

# Use fdisk to change a partition to be added to ID 8e
fdisk /dev/sdb 
# Make /dev/sdb1 a physical volume 
pvcreate /dev/sdb1
# Add /dev/sdb1 to the volume group 
vgextend -v vg_dvd01 /dev/sdb1
# Resize the target logical volume to use 100% free space of the volume group
lvresize -l +100%FREE /dev/vg_dvd01/lv_home
# Umount the file system first to speed up the resize operation
umount /home
# Do the resize
resize2fs /dev/vg_dvd01/lv_home
# Mount it back
mount /home

Create a few users on the just installed Linux

# Create the group first with group ID 1000
groupadd -g 1000 dvdgrp1

# Create the first user with user ID 1000
useradd -u 1000 -g dvdgrp1 user1

# Add other users
for i in user2 user3 user4 user5 user6 user7 user8 user9 user10
do
    useradd -g dvdgrp1 $i
done

# Set initial password to the same as user name
for i in user1 user2 user3 user4 user5 user6 user7 user8 user9 user10
do
    echo $i | passwd --stdin $i
done

Enable Samba server in CentOS 6.3

1. Install Samba
   yum install samba samba-common 
2. Edit Samba config file
   vi /etc/samba/smb.conf
1. In the [global] section
           security = user
           passdb backend = tdbsam
           # Set to follow symbolic links
           follow symlinks = yes
           wide links = yes
           unix extensions = no
2. In the [homes] section
           comment = Home Directories
           browseable = no
           writable = yes
           valid users = %S
           create mask = 0664
           directory mask = 0775
3. Enable Samba in run levels 2, 3, 4, 5
   chkconfig --levels 2345 smb on
4. Start the just installed Samba
   /etc/init.d/smb start
5. Add users with default password as user name
   for i in user1 user2 user3 user4 user5
   do
           echo -e $i\\n$i | smbpasswd -a -s $i
   done
6. Add these lines to /etc/sysconfig/iptables
   -A INPUT -m state --state NEW -m udp -p udp --dport 137 -j ACCEPT
   -A INPUT -m state --state NEW -m udp -p udp --dport 138 -j ACCEPT
   -A INPUT -m state --state NEW -m tcp -p tcp --dport 139 -j ACCEPT
7. Restart iptables
   service iptables restart
8. Let SELinux enable Samba home dirs
   setsebool -P samba_enable_home_dirs on

For more details, see http://wiki.centos.org/HowTos/SetUpSamba

在 Ubuntu 的命令列燒 CD

在這裡看來的
https://help.ubuntu.com/community/CdDvd/Burning

# Create ISO image

genisoimage -r -J -o /tmp/cd_image.iso MP3_DIRECTORY/
# List devices

wodim --devices

# Blank the CD-RW first @ 4x speed

wodim -vv dev=/dev/scd0 blank=fast speed=4

# Burn the image

wodim dev=/dev/scd0 -v -data /tmp/cd_image.iso speed=4

Build Emacs 23 on Ubuntu 6.06 LTS

1. Packages to be installed before build Emacs
sudo aptitude install build-essential libxpm-dev libungif4-dev libtiff4-dev libjpeg-dev libgtk2.0-dev xaw3dg-dev libdbus-glib-1-dev libgpmg1-dev libgnome-dev libotf-dev

2. Configure and make Emacs
tar axf emacs-23.3.tar.bz2
mkdir bld
cd bld
../emacs-23.3/configure --without-pop --with-x-toolkit
make

3. The result (click to see the rendering of TrueType font)

4. If only console mode Emacs is needed, configure and make Emacs as
tar axf emacs-23.3.tar.bz2
mkdir bld
cd bld
../emacs-23.3/configure --without-x
make

免安裝 dos2unix 就可以達到一樣的效果

cat orig_file | col -b > new_file
tr -d "\015" < orig_file > new_file

你說那 unix2dos 呢？
對不起，沒有這種需要。

Install telnetd

如果只是為了要開發用，在 virtual machine 上裝 SSH server 實在是有點浪費 CPU，因為中間的連線都是在本機上，卻還要做不必要的 encryption/decryption。

可以只裝 telnetd 就好了，像這樣：

sudo apt-get install telnetd

sudo /etc/init.d/openbsd-inetd start

然後就可以 telnet 進去了，心裡上會快一點。