part 3 of (useful post must see) Everything about overclocking kernels governors, i/o schedulers e.t.c

3. MODULES

A loadable kernel module is an object that contains some code to extend your kernel. Modules serves various type of purposes like support for new hardwares, filesystems, and system calls. It is probable that once a new module is inserted, it might cause minor fragmentation in kernel resulting in a minor performance penalty. Mostly, not noticeable.
We might ask "ok, if kernel modules are so amazing, why not add them all into the kernel code instead of asking us to load them". Well, the advantage to LKMs is that you can minimize the memory footprint for a kernel, loading only those elements that are needed.

You can find all the modules in /lib/modules. (With extension .ko = Kernel Object).

To avail a module, you need to install/insert it by:

Code:

insmod /lib/modules/module-name.ko

Put the line in an init.d script to load the module(s) on every boot.

To view the list of modules that are loaded by default, use:

Code:

lsmod

To unload/remove a module (that has been loaded):

Code:

rmmod "modulename"

1) bthid.ko* - BlueTooth Human Interface Device

Signifies: Bluetooth
Bthid is one of the bluetooth profiles. The module provides support for devices such as bluetooth mice, joysticks,keyboards,etc. It uses a low latency link with low power requirement to achieve the above mentioned.

2) cifs.ko - Common Internet File System

Signifies: Network Share
Successor to the SMB (Server Message Block) protocol, this protocol is supported by windows servers, samba, etc. The module is responsible for managing your network shares. It is used to mount/unmount network file resources on to your device. If special characters are not properly read/displayed, download and use nls_utf8.ko module for UTF-8 character support.

3) fuse.ko* - File System in Userspace

Signifies: File System
The module let the users create own filesystems without editing kernel code. Fuse module act as a bridge between filesystem code running in the userspace and kernel interface. The module is often used in our devices to support ntfs/ntfs-3g filesystem for mounting ntfs formatted hard drives and pen drives.

4) cuse.ko - Character Devices in User Space

Signifies: Audio Proxying
CUSE is an extension of FUSE allowing character devices to be implemented in userspace. One of the prime motivation for developing cuse is to provide a better support for Open Sound System or OSS. Except for initialization sequence and creation of character device instead of a mount, CUSE isn't very different from FUSE. CUSE is used for tasks like proxying OSS audio from OSS apps to an audio system.

5) dhd.ko - Dongle Host Driver

Signifies: Wifi
This module (from broadcom) is the wifi kernel module/wireless driver, and is responsible for wifi tethering, and such.

6) ftdi_sio.ko - Future Technology Devices International - Serial I/O

Signifies: USB Serial Devices
The module is required to connect an embedded device to our device using FTDI USB-serial converter. The embedded device will be an ftdi chipset based device. Devices like an USB-RFID reader could be connected.

7) usbserial.ko - USB Serial

Signifies: USB Serial Modems
This module is often used along with ftdi_sio module. It is the usbserial-generic interface for linux platform. The module is used to detect and use devices such as usb serial modems.

8) gspca_main.ko - GSPCA Main Driver

Signifies: Webcams
This module is used to install gspca based web camera in our device. The module is the driver that's responsible for detecting and functioning of gspca based webcams.

9) hfs.ko - Hierarchical File System

Signifies: Mac Filesystem
This module is the driver to support HFS aka Mac OS Standard file system. Try mount -t hfs "/source" "/destination" to mount. Also give USB Mass Storage Watcher App from market a try, to skip commands and mount via GUI.

10) hfsplus.ko - Hierarchical File System Plus

Signifies: Mac Filesystem
This module acts as the driver for HFS+ aka Mac OS Extended file system. HFS+ is one of the formats found in iPods. Use mount -t hfsplus "/source" "/destination" for mounting drives.

11) j4fs.ko* - Jong Jang Jintae Jongmin File System

Signifies: File System
J4fs is a filesystem based on LFS (Linear File Store). The bootlogo and some misc files in our device, mounted in /mnt/.lfs is formatted as j4fs filesystem by default.
Please do not mess with .lfs folder!

12) ld9040_voodoo.ko* - LD9040 AMOLED Driver

Signifies: Voodoo Color
Module/driver for voodoo color/screen tuning support for our device. Let's wait patiently until supercurio comes out with a legendary app to have full control on our amoled display.

13) scsi_wait_scan.ko - Small Computer System Interface Wait Scan

Signifies: Waiting During Booting
scsi_scan_wait is responsible to wait until all the asynchronous scans are complete. It will wait after all root SCSI drivers have finished scanning their busses. Note that use of this module can increase your bootup time.

14) Si4709_driver.ko* - Si4709 FM Radio Driver

Signifies: FM Radio
Si4709 is the fm radio receiver driver. Module is loaded by default by Siyah. If there are issues with fm radio in aosp roms, try inserting this module.

15) vibrator.ko* - Vibrate Sensation on Touchsense

Signifies: Haptic feedback
This module from immersion corporation is responsible for haptic feedback. It senses touch as a request and sends back vibration as response. Try inserting this module if haptic feedback not working on aosp roms.

16) logger.ko - Logger for Android

Signifies: Logging/Debugging
Loggers are used to log records to a variety of destinations such as log files or the console. Install this module to enable logging, if logging is disabled in your kernel by default. Logging is used to generate logcats (for debugging purpose), dmesgs (message buffer of the kernel), for proper functioning of app protectors, etc.

17) mc1n2_voodoo.ko - mc1n2 Voodoo Sound Driver

Signifies: Voodoo Sound
Module/driver for Exynos Yamaha audio hardware tweaks. Provides sysfs interface for HP gain and Aout. This driver provides support for supercurio's Voodoo Louder app.

18-25) cpufreq_ brazilianwax.ko, cpufreq_ interactive.ko, cpufreq_ interactivex.ko, cpufreq_ lazy.ko, ondemandX.ko, cpufreq_ powersave.ko, cpufreq_ savagedzen.ko, cpufreq_ userspace.ko

Insert these module(s) to avail your favorite governor which are not loaded by default.

*Modules preloaded in Siyah by default.


Q&A

Q. "I can not find a module that i need to use with the current release of my kernel. Can i use the module downloaded from internet?"
A. Module should be binary compatible with the kernel version. So even if the module was one that came with an older version of the kernel, it's probable that the compatibility is lost.

Q. "I feel there could be some advantage if i remove modules which is no use for me, but they're loaded by kernel during boot-up. What can i do?"
A. Put "rmmod name-of-module" in one of your init.d script, so that it's uninstalled on every boot-up. After booting if you need to use the module, you can insmod it. Ex: rmmod Si4709_driver.ko. (If you don't use FM radio)

part 4 coming soon