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Root Want to flash a kernal, but...

corybantic

Well-Known Member
Apr 14, 2011
174
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Turn around...
I'm a bit skiddish about flashing a kernal for better battery life because after 2 weeks of being rooted, I've finally gotten my phone configurated/customized the way I like it. I've flashed kernals in the past (using Rom Manager) and each time I did, I had to start over from scratch. My question is this: Can I flash a kernal without losing my current configuration/customized settings? If so how? I have Titanium Backup, could I just back up everything, flash the kernel and then restore???? Thanks for your input.
 
I'm a bit skiddish about flashing a kernal for better battery life because after 2 weeks of being rooted, I've finally gotten my phone configurated/customized the way I like it. I've flashed kernals in the past (using Rom Manager) and each time I did, I had to start over from scratch. My question is this: Can I flash a kernal without losing my current configuration/customized settings? If so how? I have Titanium Backup, could I just back up everything, flash the kernel and then restore???? Thanks for your input.

Not Titanium. You want to do a NANDroid backup, which can be done either via recovery, or you can use ROM Manager's "Backup current ROM" feature.

If you then flash a kernel and everything goes to shit, you'll have to restore the NANDroid backup via recovery, so it pays to learn how to do it via recovery rather than ROM Manager.

Some kernels are made for Sense. Some are made for AOSP. Some are designed to be universal. In general, it pays to stick with Sense- or AOSP-specific kernels. If you consistently have problems flashing any kernel, you may want to do a full wipe before flashing it. If you do a full wipe, you DO want to use Titanium to back everything up, so you won't have to set up everything from scratch.

NANDroid backups are good for when you want to go back to a previous state the phone was in. Titanium backups are good when you've wiped your data and want to restore it onto whatever new OS/ROM you're running.
 
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So then I would have to do a NANDroid, wipe dalvic-cache, flash the kernel, reboot, and then restore configurations with Titanium backup? Is that correct?

Short answer, no. When you flash a kernel, the kernel is replaced, and that's it....It's not like flashing a ROM, where you have to reconfigure everything over from scratch. In other words, when you flash a kernel, all your settings and apps and everything else will remain the same, Nova is recommending doing a nandroid prior because if the kernel proves to be unstable on your Evo (ie: screen tearing, random reboots, boot loops, etc.), you can always restore your phone to how it was before flashing the new kernel.
 
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When you flashed the kernel all you wiped was cache and dalvik therefore all your data is retained as you did NOT wipe system and data. Dalvik rebuilds and cache is well just that, cache, so those dont really contain any of your "set up"

So make a nandroid, wipe cache, wipe dalvik, flash kernel, reboot, done. Everything will remain.
 
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I'm a bit skiddish about flashing a kernal for better battery life because after 2 weeks of being rooted, I've finally gotten my phone configurated/customized the way I like it. I've flashed kernals in the past (using Rom Manager) and each time I did, I had to start over from scratch. My question is this: Can I flash a kernal without losing my current configuration/customized settings? If so how? I have Titanium Backup, could I just back up everything, flash the kernel and then restore???? Thanks for your input.

Don't wipe your data. I don't think its necessary to do so.
 
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just so you know what's ACTUALLY happening...

kernel lives in the /boot partition.
the operating system lives in /system partition.
your data lives in the /data partition
cache is in the /cache partition.

A custom ROM includes a kernel and OS, so when you flash a ROM, it's writing to multiple partitions. If you're flashing the kernel only, you're just replacing /boot. Everything in /data is still intact.

A factory data reset wipes /data and /cache. /system is untouched, which is why you stay on the same OS version after the factory data reset.

Typically, you only need Titanium if you're flashing something that replaces /system (new ROM).

NANDroids are good to preserve a particular state of your phone so you can go back to it if needed.
 
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