Database Info

kernels..

hey guys.. i guess im kinda new with androids but all i have is a question... now the i learned how to flash a rom.. its very cool but why do we need kernels what does it mean? just flashing a rom thats not all there are kernels and other stuff but i dont know what they are and what for

Kernels are the core system. Sort of like drivers. Custom Kernels affect stuff like Overclocking for speed, Undervolting the processor to save battery, GPS locks, WiFi range, etc.
They can increase stability, speed, and battery.
The big thing, I think, that most people sought after is the Overclocking/Undervolting (OC/UV). This overclocks the processor while lowering the power usage of the chip at the same time. So you get a faster phone while saving battery. Brilliant. It is my understanding that custom kernels come with normal settings by default. They only ALLOW overclocking abilities using programs like SetCPU and the likes. I think the voltage is lowered on all speeds though, so flashing an UV rom will save you battery even if running 1ghz stock speed. I've seen people go up to 1.4ghz.
It is best to test a rom first for a few days. Figure out what bugs you encounter, if any. Get a feel for the rom so when you flash a new kernel you can see if it will work for you. If you do too much at once and you encounter bugs it will be hard to pinpoint.
I've flashed custom kernels but don't do it often. I know CM roms have their own custom kernels that I believe are flashed back when flashing the rom. This is why CM7 differs from stock in a lot of ways. One example is stock G2x won't work with Wii remotes. The bluetooth stack in the kernel is a custom LG one and doesn't work. CM uses a more common bluetooth stack so you not only gain this functionality but also others.
The list goes on and on. I think most of the custom kernels are BASED off CM7 and are only compatible with CM7. I think a custom kernel on top of a stock LG rom will cause bootloops. So the kernel and rom have to work together.
I am not an expert but I think I've touched the bases. Someone correct me if anything is untrue or misinformative. Technicalities aside, this is the gist of it.

player911 said:
Kernels are the core system. Sort of like drivers. Custom Kernels affect stuff like Overclocking for speed, Undervolting the processor to save battery, GPS locks, WiFi range, etc.
...<snip>
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excellent explanation, i've kinda been wondering about all this myself. Thanks!

player911 said:
Kernels are the core system. Sort of like drivers. Custom Kernels affect stuff like Overclocking for speed, Undervolting the processor to save battery, GPS locks, WiFi range, etc.
They can increase stability, speed, and battery.
The big thing, I think, that most people sought after is the Overclocking/Undervolting (OC/UV). This overclocks the processor while lowering the power usage of the chip at the same time. So you get a faster phone while saving battery. Brilliant. It is my understanding that custom kernels come with normal settings by default. They only ALLOW overclocking abilities using programs like SetCPU and the likes. I think the voltage is lowered on all speeds though, so flashing an UV rom will save you battery even if running 1ghz stock speed. I've seen people go up to 1.4ghz.
It is best to test a rom first for a few days. Figure out what bugs you encounter, if any. Get a feel for the rom so when you flash a new kernel you can see if it will work for you. If you do too much at once and you encounter bugs it will be hard to pinpoint.
I've flashed custom kernels but don't do it often. I know CM roms have their own custom kernels that I believe are flashed back when flashing the rom. This is why CM7 differs from stock in a lot of ways. One example is stock G2x won't work with Wii remotes. The bluetooth stack in the kernel is a custom LG one and doesn't work. CM uses a more common bluetooth stack so you not only gain this functionality but also others.
The list goes on and on. I think most of the custom kernels are BASED off CM7 and are only compatible with CM7. I think a custom kernel on top of a stock LG rom will cause bootloops. So the kernel and rom have to work together.
I am not an expert but I think I've touched the bases. Someone correct me if anything is untrue or misinformative. Technicalities aside, this is the gist of it.
Click to expand...
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Ya, thanks for putting the time into explaining. I was wondering the same thing..

Wow that was briliant thank you...
Sent from my LG-P999 using XDA Premium App

[Q] Prime 1.8.4 (No Custom Kernel) VS. Revolver

I'm struggling to recognize the benefit of a custom kernel on prime.
Also, Revolver has piqued my interest. I've seen other posts that are similar to this, but not quite as detailed as i'd like.
What does a custom kernel bring you? I have Prime 1.8.4 and haven't even really recognized the difference between in and the stock firmware.
Please be patient, i'm new to the Android OS.
So, to rehash, im looking for information on:
The benefits of Prime.
The benefits of a custom kernel + prime or revolver.
The benefits of Revolver.
Revolver + a custom kernel.
I'm appreciate the fact that you guys may not have time to indulge a noob like me. If anyone can help me find the resources i need, i'd greatly greatly greatly appreciate it!!!!
The guides & how-to's on this site are amazing, and i realize that most of this stuff is geared toward developers (i plan on developing, and have just begun my studies. I shall be as amazing as you all one day!!!) but i'm missing quite a bit of information. Few of the guides i've seen speak of what the software actually is/is intended to do/be, or how it's different.
P.S. If anyone has any idea if there is a ROM/ Android dev wiki, i'd appreciate the location of it.
If not, i think ill start one!

I saw a thread that kinda talked about what a kernel is, but I think, for me, I use Clemsyn kernel because it allows me to overclock (overclocking at 1400~1504 atm) up to 1600ghz. That lets your tablet run faster than the factory setting (which sets it lower for less chance of a burn out). Other than that, I don't really know either and I'd like to hear some replies too =D.

its basically similar to the benefits of a custom rom. it lets you...
1) overclock
2) adds support for kernel modules like ntfs, cifs, 3g.....
3) can allow for optimizations

clemsyn is always playing with bus speeds and memory timings to squeeze the most performance out of the tablet. he also adds modules and functionality like the poster above said.

I like custom roms because they do awesome things, like compile tun and cifs support into the kernel. now, i have been on prime for some time, but a lot of things seemed to be a little snappier over the stock rom.
i don't bother overclocking.

[Q] can't decide on a custom [NS4G] ROM & Kernel

I'm sorry about the long post if you want to get straight to my question, skip the first paragraph
I was avoiding this because it is a fairly noob question set (and I've seen a history of new members on XDA being berated for questions that could have been answered by any amount of research and I'm unsure whether my question set will fall into that category), but I just can't do anymore research since most information I'm finding is not in one place and I can't seem to find a full feature list for any of the ROMs and Kernels I research and look into, and on top of that there are SOOO many.... I'm about to pull my hair out of my head and my skull along with it, and every search engine I use is contemplating homicide (google has divorced me and is planning my murder for the life insurance money, and duck-duck-go is biting my heels with its bill) and firefox is planning a suicide bombing taking the 50 or more tabs with it along with my RAM, and I'm not terribly sure any of those actions aren't justified (and also, as you can probably tell, I'm going NUTS!). Just the amount of information and the amount of digging I have to do to find a single answer for the MANY questions I have regarding these ROMs and Kernels is staggering (I remember having similar problems searching to find the right linux distribution for me, but it wasn't this hard and after 2 or more weeks of searching, I didn't find myself not having any substantial answer, nor did it actually take two weeks)
anyways, enough with the crazy intro to the question
My current phone is a Nexus S 4g (sprint) currently running the stock ROM and Kernel, gingerbread 2.3.7 (build GWK74). I have it rooted and I have clockwork mod recovery flashed as well as ROM manager installed. I'm looking for ROM and Kernel recommendations (and combinations, I want to make sure they're compatible) as well as reasons why they might fit my needs
I need a ROM and Kernel that:
1. Won't reduce any of the current features I have on the Stock ROM/Kernel I have (though I don't use NFC so if google wallet isn't applicable, that's not a loss)
2. Will allow more steps in frequencies on my CPU (so CPUtuner won't tell me it can only go between 100Mhz and 1Ghz when I attempt to manually change the frequency, I can get one governor to get me 400mhz, but that only adds one more step to the 2 current steps, and performance and powersave governors don't work with the stock kernel, not that it's a big deal, I prefer conservative and ondemand)
3. will allow voodoo control & voodoo color (or any other feature that might be useful, though BLN isn't a big deal to me)
4. Has better battery life (while in use, use being things similar to internet browsing) than stock ROM/Kernel (so UI flare isn't completely necessary, and underclocking and/or undervolting would be great, as long as it doesn't sacrifice speed)
5. The UI should be less jittery than I'm seeing the stock react half the time (though that might be an effect of the CPU tuner)
6. I would like overclocking (however if that interferes with battery life, then I can live without it as long as it doesn't make the speed worse than stock)
7. this coincides with #1, but I think it should be said anyways: I don't want any connectivity (besides maybe NFC) to be affected adversely, so I want 4g, 3g (given), wifi, tethering, etc...
a few questions I have that I can't seem to clear up:
1. I'm beginning to develop software for android, so I'm wondering if any ROM and/or Kernel will affect ADB or any connection to my PC at all
2. What advantages do CM7.1 nightlies have over the CM7.1 stable, and any disadvantages (because I would prefer stable unless there's something on the nightlies I might want)
3. And any advantages ICS ports might have to anything listed above? and compatible kernels?
well, I have done some research, and the two ROMs I'm currently considering are Oxygen and CM7.1 (stable). I like Oxygen because it's a barebones rom with a few extra features that (from what I've seen thus far) don't interfere with performance or battery life. I like CM7.1 because it seems to be fairly quick and has a good feature set.
now I know that the performance might be more affected by the kernel than the ROM, so the kernels I've been most interested in are Netarchy and Trinity. Netarchy has decent speeds (though I'm unsure of its effect on battery life) and has a great list of features (such as voodoo control). Trinity is fast (depending on which version, I was debating on the overclocked version that doesn't go to the highest clock setting and the undervolted version which stayed at 1ghz but had great powersaving) because of its speed and/or powersaving, but I'm unsure of all of the features it has)
I had read that CM has its own kernel, but I can't find any substantial evidence to it besides a few short forum posts on various forums. I can't find anything on the CM site that backs up those claims (I could have just missed it though)
I was considering MIUI but I had heard that it had some translation problems from chinese into english and I'm not sure if you can get the text to read from left to right (and be alligned that way). Not sure if that has been fixed and if the features on there are necessary and/or make it difficult to use
I'm asking here because I'm sure I've barely scratched the surface on all of the ROMs and Kernels that might be helpful to me (and hope to get info from more knowledgeable people)
I have been referring to this thread
http://forum.xda-developers.com/showthread.php?t=1067813
I'm sure somethings I want aren't possible or if they are, there's negligible gain (I'm starting to thing that about battery life with the more I read)
once again, I apologize for the extremely long post, as you can tell I'm verbose (as it's really the only way I know how to get my point across)
if you need further information, feel free to ask. If any information needs to be cut off (especially if this needs to be cut shorter) let me know

I hate to do this but
BUMP
my main problem with this is that most of these roms and kernels seem to do the same thing but all have different problems
I've also found that some versions are more buggy then others which has thrown yet another curve ball into my research (not as bad as ICS but bad enough). I should have expected it but it's just one more thing to go digging for
an answer at all would be nice, other than just the views with no post. Even if the next person's answer is "this is stupid" or something of the like
even that would help me believe it or not

Honestly, your answer is the same one everyone else gets. Try them out and see. Most of the kernels out there should work with any of the ROMs, even the stock ROM. Personally, I have had no real issues with any ROM/kernel combo I have tried. I use CM because I am so used to the features they add and I dislike the stock GB theme. I'm using the last nightly cm7 had because there was something they didn't have in the stable but I don't recall what that was. But most any ROM or kernel you get for gB is likely done being developed for. The combination in my signature serves me very well. A lot of people do like oxygen. I just missed cm too much. Most of the kernels should allow for all of the wants you have.
I also ran cm9 with the glados kernel and honestly, it ran perfect for me. My only issue was with a few apps i use not wanting to cooperate.
Sent from my Nexus S 4G running CM7/franco.Kernel
Sent from my Nexus S 4G running CM7/franco.Kernel

alright thanks (which the button did for me)
I understand that (and some threads I looked over had answers like that, so I figured someone might say something along the lines of "try it out") I was mostly looking for input from past users about some ROM or kernel
I just don't want to end up with a broken phone before I leave for a week or two (to a rural area for a couple of days)
thanks for the answer, all I really need to know now is have there been any problems with any of them running ADB or transferring files from PC to phone?
EDIT: well I'm going to continue trying to get android SDK working on my linux OS, and I'm going to install and run a few ROMs and Kernels
ROMs I'm going to try: CM7.1 Stable, Oxygen, CM9
Kernels: Netarchy, Trinity, matri1x, and glados (with CM9)

Roms and Power use - curious to know the answer

So I'm just wanting to increase my own understanding of how things work, plus I see people ask this question about specific rom's often. Given 2 different roms with identical kernels and identical setups, how do you explain different power usage and battery life?
In other words, why would you see a noticeable difference in battery life with one rom vs another, given all apps equal and kernels equal?

kingston73 said:
So I'm just wanting to increase my own understanding of how things work, plus I see people ask this question about specific rom's often. Given 2 different roms with identical kernels and identical setups, how do you explain different power usage and battery life?
In other words, why would you see a noticeable difference in battery life with one rom vs another, given all apps equal and kernels equal?
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Hi,
I think it's a well known fact that not all phones are created equal.
Plus,no two people use their phone in the same way.
So,you will get variations all the time.

I think the OP is talking about 1 user and 1 phone having different results (different power usage and battery life) with roms that use the same base, kernel, etc.
I personally think that certain devs tweak some settings a little and the slight difference we notice comes from this. But since I'm not a Pro, I'm going to let someone else answer it, as I been looking for this answer.
Thanks OP for asking it.

rasco702 said:
I think the OP is talking about 1 user and 1 phone having different results (different power usage and battery life) with roms that use the same base, kernel, etc.
I personally think that certain devs tweak some settings a little and the slight difference we notice comes from this. But since I'm not a Pro, I'm going to let someone else answer it, as I been looking for this answer.
Thanks OP for asking it.
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Click to collapse
Hi,
Sorry, I mis-read.
You are right about the Devs doing their own thing,and tweaking every ROM differently.
They are always trying to squeeze every drop of improvement out of the ROM for the user.
Mike 1986 is a good example of this.
On every changelog of his are the words:
"Other minor changes and fixes"

rasco702 said:
I think the OP is talking about 1 user and 1 phone having different results (different power usage and battery life) with roms that use the same base, kernel, etc.
I personally think that certain devs tweak some settings a little and the slight difference we notice comes from this. But since I'm not a Pro, I'm going to let someone else answer it, as I been looking for this answer.
Thanks OP for asking it.
Click to expand...
Click to collapse
That's exactly what I'm asking. I'm not wondering why I get different results from you, I'm wondering why I get different results from one rom to the next with MY phone and MY same apps etc.

Best 4.4.4 based ROM?

I am looking for a secondary ROM for MultiROM but Lollipop-based roms seem to freeze if they are not primary.
What is the most feature-rich, stable and battery-sipping ROM out there for Nexus 5 running 4.4.4?

There is no best ROM. Read the rules. These kind of post aren't allowed regardless of how you word them.
Flash all the 4.4 Roms, try them out and decide for yourself. Not everyone likes what you like, or has a set up like yours. Decide for yourself.

jayRokk said:
There is no best ROM. Read the rules. These kind of post aren't allowed regardless of how you word them.
Flash all the 4.4 Roms, try them out and decide for yourself. Not everyone likes what you like, or has a set up like yours. Decide for yourself.
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Click to collapse
Unfortunately, the admin team have decided they are allowed. That's why I'll post my answer which I keep in ever note:
"Best" ROM.
There is no such thing as a best ROM.* The question itself is*ambiguous.* "Best" is obviously a subjective term.
What I want from a ROM may well differ from what you want from a ROM,*ergo - what is best for me could be worst for you.
If you are asking what the most popular ROMs are, or which ROMs people*are using, you can see which threads stay around on the first few*pages (and have the most posts) in the*Android*Development or*Original*Android Development forums. You can also see what other people*are running by reading the*What*are you running on your Nexus 5 thread.
If you are asking which is the most stable, being a Nexus device -*they're all pretty stable.
If you are asking which is best on Battery, ROMs only affect battery*if they have a feature that is badly coded.* You will likely be able*to read about this in the ROM threads.* ROMs do not impact battery*life.* The only impact to battery life are your apps, your settings,*how you use the phone and mostly, environmental issues such as Phone*Signal.
For tips about improving battery life, please read*[Battery*Life Help] Troubleshoot battery issues here!
"Best" Kernel
Also, please note that as above, "best" is still subjective.* What we*all want from a kernel is different. Again, many people have the*misconception that Kernels affect battery life.* Let's get this*cleared up.* Although Kernel devs will build in optimisations and*efficiencies that will improve battery life, these are very, VERY*tiny...and if 1 kernel has these optimisations, they likely all have.
People will often say "Kernel x is better than kernel y for battery*life".* This is actually wrong. *Kernels respond to user settings.*Setting up the governor to favour either battery life or performance*is simple enough to do, you just have to do some learning.* The reason*people think Kernel x is better than y is because developers set their*kernels up with their preferred governor settings.* This is what we*refer to as out-of-the-box settings.* The out-of-the-box settings for*kernel x may well produce better battery results than the*out-of-the-box settings for kernel y, which favour performance.* The*fact is, you as the user have the ability to tune kernel x or y to*perform the same, be that battery or performance - so start learning*how to do this yourselves - that way, you can choose the kernel based*on the FEATURES you want, and not the fictional performance benefits*of one kernel over another.
Hope this helps

I'll play along and throw out a suggestion...my all time favorite ROM (notice I said favorite not BEST) is dirty unicorns which has a 4.4.4 version. Its full of awesome aosp features. Almost everything is customizable within the "dirty tweaks" section in the settings menu. It was my daily for a year before upgrading to lollipop.
Sent from my Nexus 5 using xda premium

rootSU said:
Unfortunately, the admin team have decided they are allowed.
Click to expand...
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Well there goes XDA

harrisonp said:
I am looking for a secondary ROM for MultiROM but Lollipop-based roms seem to freeze if they are not primary.
What is the most feature-rich, stable and battery-sipping ROM out there for Nexus 5 running 4.4.4?
Click to expand...
Click to collapse
These threads are stupid. Ask 10 people, you'll get 10 different answers. Read the OP's of all the ROM threads in development, decide which one has the features you want and flash it.
And FYI, I have two Lollipop ROMs on my N5 with multiROM, neither of which are my primary, and both run perfectly fine.

_MetalHead_ said:
These threads are stupid. Ask 10 people, you'll get 10 different answers. Read the OP's of all the ROM threads in development, decide which one has the features you want and flash it.
And FYI, I have two Lollipop ROMs on my N5 with multiROM, neither of which are my primary, and both run perfectly fine.
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Click to collapse
I've been running lollipop for several weeks. No problems. Daily driver.

Thank you for dispelling misconceptions of mine. I am a bit overwhelmed with choices when it comes to KitKat, which is a sign of an active, interested and motivated development community.