Develop Bugs

Questions about Kernel, Recovery. (noob alert!)

I've tried searching for these things, but all the info seems to be very fragmented.
If someone can give me a simple answer, I would greatly appreciate it.
Kernel - Do I need to flash a new one when installing a new ROM, or is it already in there? Do I just flash it by having a .zip on my sdcard?
Recovery - is this just a shell for bootloader (terminology from the winmo days i guess)? Are there differences, one better than another?
I'd like to install the stock 2.2 ROM that netarchy released, but there is a lot of talk about kernels as related to wifi and FPS, so I wanted to see what that's all about.
Thanks.

Kernel Answers:
No. When flashing a new rom a kernel is included. Kernels are packaged up in the boot.img files inside the rom.zip. Now, with HTC Sense phones there are two types of kernels. HTC kernels and Android kernels. HTC builds their phones in such a way that a standard Android kernel will not work. This is why we need to wait for the kernel source code from them. It also depends what OS is on the device. If you have a stock Sense rom it will use a different kernel than an AOSP rom such as CyanogenMod. So as an example, you are unable to use any CM6 kernel with Sense or vice versa.
My point is this. Be careful. If you want a modified kernel make sure it is for your rom or is compatible with your rom.
Recovery Answers:
No. Recovery is different than the bootloader. Recovery is a mode built into the phone so that, assuming something goes wrong and Android doesn't boot, you can boot into recovery and flash different files. This is only meant for HTC employees however at XDA we always find a way to use this recovery for our own purposes. We take HTC's recovery, erase it and flash our own recovery over it. This allows us to backup and restore our phones, flash new files to it, wipe it, etc.
So for your question. You can use the Stock 2.2 rom and Netarchy's kernel and it should work fine. Just be careful because it is a 2.6.29 kernel. The stock kernel now is 2.6.32 so some things may or may not work properly with it as FroYo was designed to run on a 2.6.32 kernel.

Thanks a bunch for the info!
So if I do the "Volume Down + Power" thing, that goes into phones native recovery menu?
Also, if the phone is rooted (via toast's or simple root), will it then have a different recovery process?
EDIT: As has been pointed out, this thread maybe better served in the Q&A section. Mods, please move this if you feel it's necessary.

Does the KERNEL decide Recovery?

Coming from the evo I can tell you I had never heard of Odin or anything like that. My question is this : I am rooted on stock now (yes I have superuser, yes I have Cwm recovery.) But I wanna flash another rom. To do that, do I have to use Odin? Or can I just dl the zip file for the Rom, flash it and go on with my life?
Also, when I flash the rom will it change my recovery? Do roms come with their own kernels? And.if they do: do those kernels come with their own recoveries?
Sorry if its wordy but I'm kinda lost Lol
Thanks!
Sent from my SPH-D710 using XDA App

Samsung is not like other platforms where the recovery and android kernels are separate. The same kernel used for Android is used for Recovery. Also when people here refer to kernel/zImage, they actually are referring to the kernel+initramfs (not the core linux kernel only)
The true linux kernel doesn't decide recovery, but since initramfs is packed with the kernel with the whole think being flash together, effectively you get whatever recovery came with the zImage you flash.
You can just flash the ROMs from CWM. No need for ODIN.
Some ROMs include kernels, some don't. If the ROM came with a kernel, you'll get whatever recovery that kernel came with.

sfhub said:
Samsung is not like other platforms where the recovery and android kernels are separate. The same kernel used for Android is used for Recovery. Also when people here refer to kernel/zImage, they actually are referring to the kernel+initramfs (not the core linux kernel only)
The true linux kernel doesn't decide recovery, but since initramfs is packed with the kernel with the whole think being flash together, effectively you get whatever recovery came with the zImage you flash.
You can just flash the ROMs from CWM. No need for ODIN.
Some ROMs include kernels, some don't. If the ROM came with a kernel, you'll get whatever recovery that kernel came with.
Click to expand...
Click to collapse
First of all, thanks for replying so.quickly. secondly, will my nandroids work? Because if I make a nandroid now, it'll get saved with cwm but what if I flash a new rom? Will I be able to restore this nandroid from that new recovery? If so, will the nandroid restore take me back to the recovery I have now?
Sent from my SPH-D710 using XDA App

oddfuturejoey said:
First of all, thanks for replying so.quickly. secondly, will my nandroids work? Because if I make a nandroid now, it'll get saved with cwm but what if I flash a new rom? Will I be able to restore this nandroid from that new recovery? If so, will the nandroid restore take me back to the recovery I have now?
Click to expand...
Click to collapse
You should be able to restore them. The only issue might be some versions of CWM can look for the NANDROID backups on internal and external SD and some only look on external.
All the CWM/kernels in the Auto Root sticky can look for them in the internal and external SD and as long as you have root you can install one of those kernels (EG30+CWM, EG31+CWM and EK02+CWM are included) You can even install from the phone without a PC using terminal after copying the files to sdcard.

Just flashed Calkulins and a couple questions

So i am new to Samsung (coming from a launch evo) and watched the QBKING77 videos and rooted and flashed Calkulins rom pretty easily. So far pretty simple but I have a question.
I am on stock EL29, What confuses me is the list of all the different modem .zip/.tar that are listed in the Caulkins thread. I couldn't really find a thread or video explaining what the difference is between the many different modems, or what the heck a modem is even. or if i should even worry about those at all. Should i just stick to the stock kernel that came with the rom? If i do decide to change the modem do i just flash/odin and im all set? or do i have to re flash the rom?
From what i learned so far, the kernel and phone radios are one in the same right?

Modem = radio. Also known as baseband under your settings - about phone. Modems are flashed independent of a ROM or kernel.
You can mix and match anytime you'd like. If you have solid service on EL29, no need to switch.
You can use any modem on any gingerbread or ics rom. If using a GB rom, you can't use an ics kernel and vice versa.
Hope that helps

.zip is for flashing via Clockwork Recovery. .tar/.bin is for flashing via ODIN. Most importantly it's vital to read and reread everything and also ask any questions before flashing, like you're doing now. I make Nandroid backups anytime I'm about to make ANY changes. Good luck.

Also keep in mind that anything with F in the version (ex FC07) is an unofficial leak. The latest official is EL29, which you are already on.
As a good practice when I switch modems, is to update PRL and profile then reboot.

Components come in the following packages. These packages will come either in .zip or .tar/.bin form.
1. Modem (Always separate, can use any Modem with any rom)
2. ROM (With Kernel or Without Kernel)
3. Kernel (With CWM or Without CWM, use ICS kernel for ICS rom. Use GB kernel for GB rom)
CWM = Flash .zip and make Nandroid backup
Odin = Download Mode flashing tool that can flash .tar/.bin. It can be used
Don't go around flashing your radio all the time. It can be dangerous and very brick easy.

Thank you guys! This is the info I needed. I'm sticking with EL29 for now since I'm having zero issues on the radio side. And I wasn't going to flash ANYTHING via Odin until I learned more about how it all worked.

Do I need to manually update the kernel when installing Calkulin's 2.9.2 ROM?
I installed Calkulins 2.9.2 ROM quite a while back and have been happy with it. I believe I am on the stock EL29 modem (my baseband version says S710.10 S.EL29).
I am confused about the kernel. When installing Calkulin's ROM, did I also install the "Rogue" kernel? Or did the kernel not change from the stock kernel that was on the phone from before.
From what I have read I believe that if I am still on the stock kernel then I would not be gaining the battery life benefits of the ROM because the scripts installed by Calkulin's ROM would not be running.
Currently my "kernel version" says "2.6.35.7-SPH-D710.EL29-CL852097". I believe that this is the stock kernel from Sprint. If I need to install the "Rogue" kernel, (1) where do I get it from and (2) how do I know I am using the right one for Calkulin's version 2.9.2 (and not V 3.0)?
Thanks for any assistance you can provide,
Kevin

You can find kernels in the wiki in the stickies in dev section. If you turn your phone off completely( no light on the buttons at them bottom). Then you push and hold volume up and power at the same time. Wait for it to go into recovery. Does it say e3 with blue letters or is there a green backround?
Sent from my SPH-D710 using Tapatalk 2

When I go into recovery on the top it says "Rogue ET Recover 1.1.2 (CWM v5.0.2.7)" and the background image says "Team Rogue". I wasn't able to find something that told me what kernel I was on.

Correct me if I'm wrong, but I believe you're on what's called a repacked stock kernel...its the stock el29 kernel with the cwm recovery added to it.
Sent from my SPH-D710 using XDA

Johnny - thats the thing I dont know; I am unsure how to tell what kernel I am on. I have always been under the impression that when I installed Calkulin's 2.9.2 ROM, that it also installed the "Rogue" kernel. But I am now under the impression that I may be on a "stock" kernel.
From what I understand about the ROM, the battery saver tweaks do not work for "stock" kernel. I never quite understood what a "repacked" kernel is.

specialkb01 said:
Johnny - thats the thing I dont know; I am unsure how to tell what kernel I am on. I have always been under the impression that when I installed Calkulin's 2.9.2 ROM, that it also installed the "Rogue" kernel. But I am now under the impression that I may be on a "stock" kernel.
From what I understand about the ROM, the battery saver tweaks do not work for "stock" kernel. I never quite understood what a "repacked" kernel is.
Click to expand...
Click to collapse
K. So there's a couple of things going on here. Let's get you some definitions.
Kernel: Essentially the backbone of the operating system. There are different stock kernels for different versions of Android (one for GB and another for ICS). A stock kernel comes with stock recovery. It is not a good idea to flash anything using this recovery (in some cases it is actually blocked so you can't).
CWM: Clock Work Mod. The original version from Chris. It is considered a "repacked" kernel. It stands apart from a regular kernel because it has a custom recovery built in. There are a few other things packed into it but the main difference is the custom recovery. The EL26 CWM is commonly referred to as stock CWM (not a stock kernel though).
Rogue: Team Rogue is the most common one you'll see for our phones. They took CWM and customized it further. They also developed custom recoveries based if the leaked ICS kernels. There was something causing bricks in the kernels they created, unfortunately we can't quite figure out why until we have source.
If you are seeing Team Rogue when opening recovery you currently have a "customized custom recovery kernel".
If you are flashing anything GB you're ok with what you have. If you're flashing ICS you'll need to use the EL26 CWM.
How this clears things up a bit.

Do I need a custom ROM to use a custom kernel?

Title says it all, really. I want to try custom kernels, but I am not sure if I need a custom ROM to do that, or if I can just flash them with a stock ROM

You can use stock.
Sent From My Old Epic 4g via XDA Premium

Matt08642 said:
Title says it all, really. I want to try custom kernels, but I am not sure if I need a custom ROM to do that, or if I can just flash them with a stock ROM
Click to expand...
Click to collapse
It depends.
You can run a custom kernel on the stock Rom, but you may be missing out without init.d support the stock Rom doesn't offer.
If you use a kernel with init.d script tweaks you should use a custom rom with support added. I know there are some very stock looking roms out there.
Sent from my Galaxy Nexus using xda premium

I ran Trinity on stock for a while. Worked great.

One more question about this:
To flash a custom kernel (specifically Franco kernel), do I just flash the small zip in CWM or the like? Also, if I want to back to 100% stock, can I just flash boot.img in fastboot mode, or will their be residual files? (I have a nandroid if I cannot do this)

Yes, flash the .zip using a custom recovery. When you flash a custom kernel, the update package may do more than just flash the kernel itself. So if you flash stock kernel (boot.img) back using fastboot, this doesn't have to be enough to fully return to the pre-custom kernel state. Restoring a nandroid will certainly do that, of course.
When you are willing to spend a few bucks, most popular kernels can be flashed using their control apps available in the play store. I know Franco's updater app allows you to fully backup the stock kernel + files before you flash a franco.kernel, and allows you to restore these backups.

ROM's and kernels

I came from a Droid X2 that had a locked bootloader. All the ROM's for it didn't change the kernel and the ROM had to be on a certain kernel to function properly.
My question is do the ROM's on Galaxy nexus come with kernel when you flash them or do you need to be on a certain kernel first or flash a kernel With the ROM while still in recovery.
The ROM I'm looking at doesn't say anything about what kernel to be on so I assume it comes with one.
Thanks,
Troy
Sent from my DROID X2 using xda app-developers app

No need to flash a custom kernel unless you want to, or unless the directions for that specific ROM instruct you to. Personally I found that my device performs better if I stay with the packaged kernel and not flash a different kernel after flashing a ROM. But others have had different results with different kernels. I would recommend sticking with the kernel packaged with your ROM to start with, that way you would know how it should perform. Then if you flash a new kernel in the future, if you start having an issue you would know it could be due to the custom kernel and not the ROM.

tshelby73 said:
I came from a Droid X2 that had a locked bootloader. All the ROM's for it didn't change the kernel and the ROM had to be on a certain kernel to function properly.
My question is do the ROM's on Galaxy nexus come with kernel when you flash them or do you need to be on a certain kernel first or flash a kernel With the ROM while still in recovery.
The ROM I'm looking at doesn't say anything about what kernel to be on so I assume it comes with one.
Thanks,
Troy
Sent from my DROID X2 using xda app-developers app
Click to expand...
Click to collapse
Some come with a kernel some do not....and there's no need to wipe cache or dalvik when flashing a kernel (as per Mr imoyseon himself)....flashing a kernel could cause a boot loop when its not compatible so just take your battery out and reflash a different one....just try some out and make sure you read allllllll of the OP whenever you flash anything