Solving the "Re-installation failed due to different application signatures" error when debugging Android apps

If you work on an android app from multiple workstations (i.e a laptop and a desktop) you might have encountered the following error, when trying to install an app for debugging on a device that has a version of the app,that was build on the other workstation.

Re-installation failed due to different application signatures.

Normally you have to go to Seetings->Apps and remove the application manually before adb can re-install it.

To solve this you need to do two things.

Copy the file debug.keystore which resides in your home_dir/.android directory to both (or all) the machines you debug from.

and second rebuild the app, using the new key.

Now the app will be "automagically" updated on the device without having to go over a manual uninstall.

NetMos 9845 Multiserial on Ubuntu 10.04

I have installed a NetMos 9845 Multiserial (8 port) card on my pc as i need several serial ports for a project.
Problem is Ubuntu does not recognize more than 4 ports by default.
To solve this you need to add a kernel boot parameter to instruct the kernel during boot to look for more serial devices.

With Grub2 on the machine, you can no longer edit the grub kernel parameters directly as Grub2 uses a templeting system.
So use your favorite editor and open (as root)

/etc/default/grub

there you will see a line

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

change it to

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash 8250.nr_uarts=8"

save the file and then issue the command

sudo update-grub

for the changes to take effect

Reboot your machine and check dmesg for the number of serial ports you now have
In my case it looks like this

:/etc/grub.d$ dmesg | grep ttyS
[ 0.709951] serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
[ 0.710235] 00:07: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
[ 0.710400] 0000:05:01.0: ttyS4 at I/O 0xc000 (irq = 19) is a 16550A
[ 0.710477] 0000:05:01.0: ttyS5 at I/O 0xc100 (irq = 19) is a 16550A
[ 0.710551] 0000:05:01.0: ttyS6 at I/O 0xc200 (irq = 19) is a 16550A
[ 0.710626] 0000:05:01.0: ttyS7 at I/O 0xc300 (irq = 19) is a 16550A
[ 0.710700] 0000:05:01.0: ttyS1 at I/O 0xc400 (irq = 19) is a 16550A
[ 0.710775] 0000:05:01.0: ttyS2 at I/O 0xc500 (irq = 19) is a 16550A

You can also check the number and setting of the serial ports using the setserial command for every port

sudo setserial /dev/ttyS7 -a
/dev/ttyS7, Line 7, UART: 16550A, Port: 0xc300, IRQ: 19
Baud_base: 115200, close_delay: 50, divisor: 0
closing_wait: 3000
Flags: spd_normal skip_test

Getting your Android phone recognized by adb for debugging

In an older post i have shown hot to get a Samsung phone "recognized" by adb for debugging.
These were the "early days" of Android development...
Since then Android got more mature (so did adb) and now there are many companies producing Android compatible phones that developers want to use for testing/debugging their apps.
One of the main issues people have in Ubuntu is how to get the correct udev rules for their phone, as there are many sites ans post with old info or targeting specific phones.
The other problem developers face is how to use the phone in debug mode without having to run adb as root.

First thing to do is have a go at the official Android dev page
It has (most of) the instruction you need to get your phone connected and recognized.

It all boils down to creating a new udev rule file and adding something like this

SUBSYSTEM=="usb", ATTR{idVendor}=="0bb4", MODE="0666", GROUP="plugdev"

Basically you have to tell udev that devices with idVendor=="0bb4" should get read/write privileges (the MODE="0666" part) for the group "plugdev"
In this example, the vendor ID 0bb4 is for HTC. The MODE assignment specifies read/write permissions, and GROUP defines which Unix group owns the device node.

It also has an extensive list of vendor id's you can use to match your device.

In case your device manufacturer is not in that list, there is an easy way to find the vendor id of your device.
Connect your device and issue

lsusb

and you will get a list of connected usb devices and their associated vendor and device id's

in my case it looks like this

Bus 008 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 007 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 015: ID 12d1:1038 Huawei Technologies Co., Ltd.
Bus 001 Device 005: ID 0d8c:000c C-Media Electronics, Inc. Audio Adapter
Bus 001 Device 004: ID 05e3:0702 Genesys Logic, Inc. USB 2.0 IDE Adapter
Bus 001 Device 003: ID 0409:0050 NEC Corp.
Bus 001 Device 002: ID 03f0:4105 Hewlett-Packard ScanJet 4370
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Locate your device (in this case it's the Huawei Technologies Co., Ltd) and the first part of the ID 12d1:1038 (i.e the 12d1) is the idVendor you need you need to put in the udev rules

Another common problem developers face is that although the udev rules are correct the phone does not connect to adb and shows up as a number of ???????????? when issuing an "adb devices" command.

The only way to get the phone connected is to start the adb with root privileges using sudo ,which in my book is a big "NoNo"
To solve this you need to set the correct user and group in the udev rules
Here is how my udev entry looks like

SUBSYSTEM=="usb", SYSFS{idVendor}=="22b8", OWNER="your-user-name" GROUP="your-group"
SUBSYSTEM=="usb", ATTR{idVendor}=="22b8", MODE="0666"

To get your username and group issue the command

id

and look for the uid and gid entries
in my case they look like this

uid=1000(stelios) gid=1000(stelios)

Use the uid name in parenthesis in the OWNER and gid name in the GROUP, restart udev and now you will be able to access the phone from adb as a normal user without having to issue sudo

Running out of inodes

Here is the problem.
Had a gazillion of small files stored in a 1TB partition and everything was fine, then we need it to move these files to a smaller partition and guess what, we could not.
What happened is that we would run out of inodes in the new smaller partition when copying the data over.

Lesson learned ?
If you create a small partition and have a ton of small files you will run out of inodes, and if you use Ext4 and have flex_bg in features, then you can't use tune2fs to increase inodes in that partition.
So then the only option is to reformat the partition and increase the number of inodes

Some would argue that you could use an other filesystem with dynamic inode allocation, but personally I would go with ext4 over any version of riserfs,xfs whatever as its way more mature.

To avoid the problem do the following when formatting:

mkfs.ext4 -I 512 /dev/foo
tune2fs -i0 -c0 -o journal_data_writeback /dev/foo

Formatting this way will give you way more inodes than a "normal" format would as it increases the inode size from the default 256.

Canon CLC 3200 Ubuntu and Debian Drivers

If you are looking for the CUPS drivers of the Canon CLC 3200 for Ubuntu and Debian you can get them from here for both 32 and 64 bit version.

http://software.canon-europe.com/products/0010073.asp

Have tested them on Ununtu 10.04 both on 32bit and 64bit machines and works great.

Using the web2py framework on Eclipse

Here is a nice post on getting web2py to work through Eclipse for faster/better debugging

web2py is one of the best Python frameworks out there are the moment and if you are into Python or looking for a framework to develop the next "killer" web app have a look at it.

Fix asterisk addons problems for Ubuntu

There is a bug in the recent asterisk-addons package shipped with Ubuntu 10.04
The result is that all the modules that are part of the package fail to load with a message like this

WARNING[13478]: loader.c:800 load_resource: Module 'app_addon_sql_mysql' could not be loaded.

Till this get fixed by the Ubuntu people here a quick fix

sudo aptitude install asterisk-dev
wget http://downloads.asterisk.org/pub/telephony/asterisk/asterisk-addons-1.6.2.1.tar.gz
tar xvzf asterisk-addons-1.6.2.1.tar.gz
cd asterisk-addons-1.6.2.1
./configure
make

sudo su

cp -a apps/*.so /usr/lib/asterisk/modules/
cp -a cdr/*.so /usr/lib/asterisk/modules/
cp -a channels/*.so /usr/lib/asterisk/modules/
cp -a formats/*.so /usr/lib/asterisk/modules/