Android Recovery

Hello friends...After a long time again getting a chance to talk on technology. My today’s blog is for mainly two types of people. Firstly those who are newbie like me to this technology about which i will discuss today and secondly for those who like to play with their cell-phones and upgrading their cell-phones.

Recovery is the feature provided to every android phone. Recovery is the concept which deals with the restoring the data back when phone failure occurs. Recovery is the feature which is provided in every Android phone. All Android devices ship with a recovery environment preinstalled. This recovery software can be used to restore the device to factory default settings, update its operating system, and perform other diagnostic tasks.

Fig1: Recovery mode

Before this let us first put a light on the two mostly used recoveries. Mainly there are two types of recoveries. The ROM which comes along with the phone i.e. they are in built such types of recovery is called as “Stock recovery”. Android devices come with Google’s recovery environment, which is often referred to as the “stock recovery.” Stock recovery is also called as 3e. Stock recovery has the features like wipe cache, Dalvik cache, reset factory settings. The stock recovery is a minimal, limited system. It’s designed to be ignored, and it can generally only flash OTA updates and ROMs provided by the device’s manufacturer, not third-party ROMs.  Stock ROM has less functionality. For this reason we use the ROM called as “Custom ROM”.

Fig2: Recovery screen

A custom recovery is a third-party recovery environment. Flashing this recovery environment onto your device replaces the default, stock recovery environment with a third-party, customized recovery environment.  A custom recovery environment does same things as the stock Android recovery does but in addition it provides some extra features. Custom recoveries have the ability to create and restore device backups. Custom recoveries allow installing custom ROMs.

                                               Fig3: Stock Recovery screen

Although CWM and TWRP are the two most popular custom recoveries, but other custom recoveries may be available for some devices.

Custom recoveries mainly fall in various categories:

1)     ClockworkMod Recovery (CWM):

CVM is the most widely used and popular recovery. It offers an application called as “ROM MANAGER”, which allows easily browsing and installing custom ROMs. CVM can restore and create. It is supported by most of the devices. CVM is widely used recovery.

Features of custom recovery:

1)     Fix permissions.

2)     Wipe cache, Dalvik cache.

3)     Wipe data.

4)     Reset factory settings

5)     Nandroid backup and restore.

6)     Install zips from internal or external sources.

7)     Used to install custom kernels or custom ROMs.

8)     Mounting.

9)     Formatting system partitions.

10)Preload.

How to install these custom ROMs:

Installing ROM varies from devices to devices. It depends on the properties of the device. Procedure for installing the custom ROM suiting your phone you can Google your model number and name.

Fig4: ROM manager screen

Purpose of custom recovery:

Custom recoveries are most useful while installing custom ROMs on device, as they provide backup, restore, and ROM-flashing features you’ll need. The device boot loader needs to be unlocked. Android offer a way to create full device backups, although this feature is hidden and requires using an adb command. One need not unlock the boot loader, install a custom ROM, or even root device to create or restore a full backup. 

 Fig5: Custom based recovery screen

2)     Team win recovery(TWRP):

Team Win Recovery project is a touch-based recovery environment. TWRP environment has a touch-based interface which one can use by tapping his fingers on on-screen buttons. TWRP even supports themes. TWRP offers ROM installation and backup features.

Fig6: TWRP based recovery

I hope the newbie like me are aware now of the what all the Android recovery consists of and its well known types. Last but not the least for this blog i would like to thank my friend Sagar R Aradwad for guiding me a walkthrough by giving a live demo of all the stages of custom recovery on my cell phone.

How to Access Blocked Websites

Hello geeks, here is a new trick for all of you. All of you had gone through a problem once that you want to access a website and it is blocked due to some reason. This problem you may face at your schools, colleges or in your office that many websites are blocked for security reasons, or some social networking sites are blocked where people like to spend much of their time etc.

Performance improvement of multi-core processors

Fig 1 and fig 2 shows architecture of processor “i7 and core to quad processor” respectively. By comparing i7 processor with previous processors we can conclude that cores in old processors shares there cache memory. This causes result in un efficient utilization of resources (cache), because when one core accessing cache memory then no other processor can access cache. He must have to wait until it is released by core. 

Fig 1.architecture of i7 processor

Fig 2.archtiecture of core to quad processor

 In i7 processor there is an independent local L2 cache memory for each core. These cache accessed by only their cores, not by others. Also there is one shared L3 cache memory of size 8mb which is shared among all four cores of i7 processor. I just think that shared memory is critical section area that means shared memory can be used by only one core at a time, these results in decreasing system performance.

Now I have an idea to overcome this is dividing shared cache in 4 same size caches as shown in fig 3. This result in when one core accessing an shared memory then other can access other shared memory thus one core does not have to wait for other core to release shared cache.

 fig3. Performance improvement of multi-core processors

 Above solution may causes deadlock. So we have to force them to use only one shared memory at a time so we can avoid deadlocks. But this approach will may result in program does not fit in that much of size.