[Optimus One, P500, V General] The_ERROR:
4. Custom ROM (generally)

What custom ROM is?

Is it save to install custom ROM? - potential problems

What I need for install?

What can custom ROM brings - kernel, update, performance, customization, theme, ....

what is ...

deodexed, zipaglined, png-optimized

JIT, HW:acceleration, VM.Heap Size, stagefright

apps2sd + dalvik2sd

custom kernel (recompiled, ...)

What custom ROM is?

Custom ROM is every somehow changed manufacturer's ROM or ROM compiled from source code of Android. "Change/s" can starts with adding/removing default application and can extend to kernels, cpu over/under-clocking, enable/disable features (ROOT, HW acceleration, ...), themes (frameworks, color, ...), keyboards and many other features.

Custom ROM is mostly distributed like signed ZIP package with included installation script for custom recovery. This ZIP is flashed via custom recovery tool.

Is it save to install custom ROM?

Yes, it is. May be I can say, that installation of custom ROM is almost mandatory, because it cost you only few minute if you will not be satisfied - you can just restore your old ROM from NAND backup, if you will be satisfied, you can keep it. And yes, you can also use backup tools like for example Astro for backup of your apps or Titanium Backup backup everything (SMS, call list, preferences, APNs, ...) and restore this in your new ROM (NOTE: In this case it's strongly recommended that both ROM should have same or very similar source/base ROM).

So, it is really simple:

1) Do NAND backup

2) Try new ROM

3) Keep new, or restore old one.

What I need for install?

1) Rooted phone

2) Installed custom recovery

3) Signed .ZIP file of ROM compatible with recovery

#) RECOMMENDED: NAND backup of your actual ROM

What does custom ROM bring

Custom ROM brings almost every feature you can image.

ex:

optimization for maximal power (games), long battery life, calling, texting, playing videos,...

awsome look - changed icons, colors, animations, wallpapers, menu, ....

simple work - feature that will short some work (add restart button, reorganized menu, shorts, gestures, ...)

allow tweaking - overclok/underclok your device, ROOT, ....

It's really not possible describe here every possibility what you can do/get with custom ROM.

what is ...

deodexed - needed for using themes. If you want replace/change some file in system (change theme) you need deodex file which you want change. In most cases it's going on services.jar which contains definition of colour for clock for example.

APKs zipaligned - optimization of APK archive, so it takes less memory and is much faster.

png-optimized - png files takes less memory, are loads faster

JIT - just-in-time compilation also known as dynamic translation, is a method to improve the runtime performance of computer programs, but it takes some time to convert into it on start.

HW:acceleration - using of HW acceleration for rendering GUI. Little increase battery consumption.

VM.Heap Size - maximum memory an application can consume

stagefright - In Android 2.2 new media framework that supports local file playback and HTTP progressive streaming

Apps2SD - (mostly DarkTremor's a2sd) If you create ext partition on your SD card, you can mount it like internal memory (you will have more space on phone memory) and move app on SD.

Dalvik2SD - move of Dalvik into SDcard (saves space)

custom kernel - compiled standard unix kernel (can bring support for features like support ext4 for example)

Links/thanks

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P500 custom ROM list; xdaforums.com

What's Deodex and Odex?; xdaforums.com

What Is Zipalign In Android And How To Make Apps Zipaligned; www.addictivetips.com

PNG compress; http://www.gotow.net/creative/wordpress/?p=79

Just-in-time compilation; wikipedia.org

VM Heap size; forum.cyanogenmod.com

stagefright; developer.android.com

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