Database Users

Inner working of a custom ROM / Kernel

To all the devs around here. Great work by the way!! Not that I wanna know all the technical details, but it would be nice to get an overview of how things work together on the GT.
I have a PC Windows and Linux background, but I don't fully understand as of yet how things blend together on the tab.
Can you explain a few things;
How come flashing a ROM doesn't wipe the entire system? Is a rom pretty much the same as a ghost image for PC?
How are system files (OS) differentiate with your media/videos for example.
If you install a custom kernel (see pershoot for example), will installing a rom overwrite the newly installed kernel, or do they reside in a different place on the disk? If so, can you explain.
How are things separated on the GTAB? Where is CWM installed, is it something similar to a PC bios that you flash with a custom bios?

The internal memory is split up (probably partitioned but it could be something else) into the system area and the user area that acts like the sd card does in most android devices. System files are in the system area, your media files are on the part acting like an sd card.
ROMs contain their own kernel which will overwrite your custom kernel but as long as the custom kernel is compatible with the ROM you can flash the custom kernel over the ROMs kernel. Im not sure if touchwiz and non-touchwiz need different kernels like htc sense.
I dont know where cwm is installed but its separate from the os.

That's a good start, but id love to hear more about the inner workings of everything. I don't want to know if X is compatible with Y. I just want to know how to work together and why A isnt overwriting B.

Wrong section buddy, go to the Q&A

i going to oversimplify this a bit to focus on the relevant portions of ROM flashing.
System partition - this is where the android operating system is installed. It contains the all of the files and apks for android to run. System apks are located here - stuff like the browser, gmail, contacts, calendar, etc. Just the apps are stored here, not their settings.
Boot partition - this is the kernel
Data partition - this is where all of your data is stored. Data includes all settings (including os settings like wifi passwords, brightness level, etc.), as well as any apps you have downloaded as well as their settings and data (example, the angry birds apk is here as well the angry birds data that contains your game progress.) Also the setting and data for the system apks mentioned above (like Gmail and the browser) are stored here.
Sdcard - on android phones this is a separate partition, but on tablets it is a pseudo partition - really just a folder on the data partition but treated like a separate partition most of the time.
When you flash a ROM without wiping anything you are just overwriting the system and boot partitions, that's why all of your data stays in tact.

Cool thanks, can someone describe how does the different options in CWM affect those partitions?
What is wiped when you do a factory reset? cache? and davlik?
I would also be interested in knbowing where does CWM resides.
Thanks

mickey78 said:
Cool thanks, can someone describe how does the different options in CWM affect those partitions?
What is wiped when you do a factory reset? cache? and davlik?
I would also be interested in knbowing where does CWM resides.
Thanks
Click to expand...
Click to collapse
A factory reset in cwm wipes data and cache. Davlik cache is wiped separately through the advanced menu. You can also wipe system, data, cache, and sdcard in the mounts section of cwm.
Cwm is a replacement of the stock recovery partition that shipped on your tablet or phone.

Questions or Problems Should Not Be Posted in the Development Forum
Please Post in the Correct Forums and Read THIS
Moving to General

[Q] Internel memory keeps decreasing

I have not installed any apps to my phones internel memory. I use titanium to move all apps except for keyboad, live wallpapers, widgets to the phone sdcard. 2 days ago I had 213mb of internel memory, now I am at 103mb of internel mrmory and I have no idea why. I tried deleting dalvik cache (dont think there is a way to move dalvik to sdcard with stock rom/kernel) and it didnt change much. Does anyone have any ideas where the memory leak is or what apps that even though are installed to the sdcard may be using up internel memory? Thank you
Saw the Dalvik2Cache.zip and that didnt do much, then saw the Dalvik_Hack under page 3 of the same thread and that seems to have made a lot more internel memory, I will keep an eye out on it and see if this is just a temporary fix or maybe its a permanent fix. It may just have been all the dalvik cache taking up space but over 100mb in 2-3 days seems like a lot of cache.
Here is the thread I followed, post # 24 by FrAsErTaG with the "CONFIRMED WORKING: http://www.mediafire.com/?3yfj8t8ld5yjez9

jgregoryj1 said:
I have not installed any apps to my phones internel memory. I use titanium to move all apps except for keyboad, live wallpapers, widgets to the phone sdcard. 2 days ago I had 213mb of internel memory, now I am at 103mb of internel mrmory and I have no idea why. I tried deleting dalvik cache (dont think there is a way to move dalvik to sdcard with stock rom/kernel) and it didnt change much. Does anyone have any ideas where the memory leak is or what apps that even though are installed to the sdcard may be using up internel memory? Thank you
Saw the Dalvik2Cache.zip and that didnt do much, then saw the Dalvik_Hack under page 3 of the same thread and that seems to have made a lot more internel memory, I will keep an eye out on it and see if this is just a temporary fix or maybe its a permanent fix. It may just have been all the dalvik cache taking up space but over 100mb in 2-3 days seems like a lot of cache.
Here is the thread I followed, post # 24 by FrAsErTaG with the "CONFIRMED WORKING: http://www.mediafire.com/?3yfj8t8ld5yjez9
Click to expand...
Click to collapse
It will most probably be the dalvik cache, .dex files can be anything up to 1-2mb+ for each app. IMO dalvik2cache is a bad idea, on the latest FW the /cache partition has been reduced to 100mb, fill that up and you will be unable to download from the market. You should try link2sd, it will work on any rooted phone with stock kernel. (as long as you make the 2nd partition fat.) And it will move the app, library and .dex files to your 2nd partition and it will mount the 2nd patition on boot so keyboards/widgets are unaffected. I have 350+ apps installed on my phone and thanks to link2sd i still have 235mb free and phone is fast as hell

Thats cool. My old phone I had the sdcard partitioned with an EXT3, I would love to do that with this phone but dont think its supported yet. I may be wrong but I have not found anything like that for the Verizon R800x. Do you know if there is a way to remove the dalvik2cache hack if I wanted to revert it back to internel memory?

jgregoryj1 said:
Thats cool. My old phone I had the sdcard partitioned with an EXT3, I would love to do that with this phone but dont think its supported yet. I may be wrong but I have not found anything like that for the Verizon R800x. Do you know if there is a way to remove the dalvik2cache hack if I wanted to revert it back to internel memory?
Click to expand...
Click to collapse
It will work on any android as long as your rooted. You need to make the 2nd partition fat though not ext2/3/4 as fat has native support so no custom kernel is needed. It calls to install-recovey.sh not init.d too so you can use stock kernel To remove dalvik2cache, unzip the zip you flashed look at the files in the .zip and delete the corresponding ones on your device

Thank you, I will do that, look through the .zip and delete the files. I already downloaded and installed the Link2sd. I am all about getting more memory out of the pathetic 400mb SE put in place, don't know why the hell they didnt just give us at least 2gb. But whatever still love the phone even with the limitation. Anyway what I ws going to say was I all for gaining memory ut not ifi ts going to make my phone crash some time down the road.

[Q] HD2 storage space

I have a quick question if i may...
Back in the times of the WM5/6.x , we could hard-reset and windows mobile would be copied from "somewhere" into it's original status.
Now, my question is, where the hell was that WM Rom stored for hard resets? Are we using that space? Am i talking crap here??
(ok, 3 questions, i know... i know... )

I think I'm talking crap too, but if so, someone can correct me!
I'm assuming the original ROM is stored in ROM, e.g. Read Only Memory, and then any changes, tweaks, additions, installs etc are then stored in RAM/storage. If you do a "Clear Storage", everything in the storage is deleted and the phone thinks it's brand new again.
DISCLAIMER: This really could be complete b****cks

From what i understand of Android, the OS uses 3 partions. cache, system, data.
Cache is self explained.
System, is mounted read only, and it's where the majority of the OS itself (Linux) binaries/conf files are stored, as well as the Android framework and apps.
Data is where shared preferences are stored, as well as downloaded and updated apps.
Now, we might already be using the space that WM used to store it's restore-backup back in the day... i just wanted confirmation

Android boot for the first time

Hello
I'd like some things to be clarified.
Why is the first boot so slow?
What actually happens at first boot?
Does it generate data/files? If so, where does it put those files. In data?
Windows, as I always thought atleast, create a copy of the installed rom and puts this in the internal memory, and then boots from these files in the internal memory, right?
Does android do the same?

axe_1337 said:
Hello
I'd like some things to be clarified.
Why is the first boot so slow?
What actually happens at first boot?
Does it generate data/files? If so, where does it put those files. In data?
Windows, as I always thought atleast, create a copy of the installed rom and puts this in the internal memory, and then boots from these files in the internal memory, right?
Does android do the same?
Click to expand...
Click to collapse
If you're still using the boot-from-sd-card method, it takes time to generate the data.img file which basically holds your data.
But if you mean for the nand, I am not really sure but I think it's the dalvik cache being generated (?). I think this because whenever I wipe dalvik, my device takes the same time to boot as first-boot. (you need a more experienced user to tell you what dalvik is and what it does, or just google it).
dalvik is put in the dalvik folder in /data/ (right?)
Last question is a yes. When you flash your ROM, the content of the "rom.zip" is extracted to your internal (so if you're asking if you can remove the ROM.zip after the installation is finished, yes you can).

Cache Partition stuck @ 60.5mb used

Why? It's been stuck at 60.5mb used and 1.2GB free according to Diskinfo forever now. Ever since I restored Madvane's unrooted B180 backup & then flashed root with Magisk.
Why does it bother me? Because I have no idea what I'm talking about and I feel like maybe Cache is storing in the Data Partition where I install my apps...? Is it?
Also with 1.2GB free in the Cache parition & 1.2GB free in the System Partition, can I just partition those and make the Data partition bigger for more available Internal Storage for apps and stuff? I mean I have external storage as default location but so many files still get installed on internal and I'd like to expand that if I could alter these partitions.
Anybody done that before or can answer my questions? Thanks! Images attached

Anyone ?

I have not read of anyone here repartitioning internal storage. I don't think it's as simple as repartitioning a PC hard drive with a GUI tool.
Do you have any tools in mind to do this repartitioning? I think it would be a highly risky operation, so be sure to make full backups and note all the original settings of existing partitions before repartitioning.
You can Google threads on people repartitioning internal storage for other phones, but note the ones who ran into problems and bricked their phones.

I wouldn't mess with the partition sizes, personally.. in theory it works, but it can trigger some arcane safeguards added by oems.
Try wiping the cache partition in twrp..? Could have gotten bugged, which would throw an error and require reformatting

Is there any indication of a problem with the cache partition?
It's biggest usage would be to download an OTA file, so unless that's happening, I would expect cache partition to remain remain mostly empty as OP reported. Probably what's in there is TWRP or stock recovery logs - you can confirm with a root file manager.
Wiping the cache partition as suggested won't harm anything and it would be interesting to know what it's reported usage is after wipe and reboot.

divineBliss said:
Is there any indication of a problem with the cache partition?
It's biggest usage would be to download an OTA file, so unless that's happening, I would expect cache partition to remain remain mostly empty as OP reported. Probably what's in there is TWRP or stock recovery logs - you can confirm with a root file manager.
Wiping the cache partition as suggested won't harm anything and it would be interesting to know what it's reported usage is after wipe and reboot.
Click to expand...
Click to collapse
I guess that was my question too. If there was any idication of an issue here. Seeing that free space I'd like to have it though.
On another note. There's no indication of anything being wrong with my Data partition but I formatted it to ext4 back when I bricked my phone in a hope it would fix something. But it seems fine. IDK what they default partition type was.

My data partition is ext4, which I believe is the stock default type.

divineBliss said:
My data partition is ext4, which I believe is the stock default type.
Click to expand...
Click to collapse
Thanks man you've been allot of help. Have you tried L-Speed? I'm thinking about trying it. I do have Kernel Auditiur installed. Don't use it.
Nothing is broke but thought about trying L-Speed.

Never heard of it. If you try it, let us know what you think.
WifiGhost said:
Thanks man you've been allot of help. Have you tried L-Speed? I'm thinking about trying it. I do have Kernel Auditiur installed. Don't use it.
Nothing is broke but thought about trying L-Speed.
Click to expand...
Click to collapse

divineBliss said:
Never heard of it. If you try it, let us know what you think.
Click to expand...
Click to collapse
I just tried it seems like a nice and easy way to tweak performance or battery.

I prefer kernel adiuator myself.. L Speed has too many generic settings which do next to nothing for actual performance, reminiscent of the many garbage tweak programs that have been out there for years. K.A. allowed for better control of the cpu governor settings, which allowed me to negate some of the impact of emui's 'battery optimization'. A little bit of entropy tweaking on top of that, and I no longer experience nearly the amount of choppiness