Editing a custom kernel - Galaxy S II Q&A, Help & Troubleshooting

Is it possible for me to edit my kernel to allow higher clock frequencies? I am trying to achieve 1700-1800mhz
Can i extract the kernel from my ROM zip?
Do I simply edit 'scaling_available_frequencies','cpuinfo_max_freq' & 'UV_mV_table'?
If so how can I gain write access to this file? Any info appreciated!
SGSII
Latest cm7 nightly

13pointseven said:
Can i extract the kernel from my ROM zip?
Yes just open in win zip win rar etc and extract zimage .
jje
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How do I open zimage
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You can't unzip the zImage and make changes. You'll need to compile the kernel from source yourself.

Ok thanks for the reply. I am currently downloading the cm7 source code from github. Can you help with regard to overclocking?
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You could try looking at the original overclocking commit and modifying it.
Why would you ever want 1.8GHz though? It'll almost certainly be unstable.
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OK so what I've sussed out so far is as Oxygen ROM is cm7 based I can extract the boot.img from stable cm7 ROM (which is the kernel) and replace it with the Oxygen boot.img thus creating oxygen 2.3.1/wolverine, clockable to 1.6ghz.
I have found a tut on unpacking ramdisk, is this the boot.img?
If so can anybody tell me how id go about further increasing clock speed once unpacked?
Any help appreciated, cheers Andy
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Like I said, it's not possible to change the available frequency steps in a compiled kernel. You can't unpack it and make changes, you've got to build it from source.

Thanks for the reply, I believe I have the source and instructions on compiling unsure what to edit. Am I rite in saying the kernel is generic to all devices and need tailoring to suite? Please forgive the noobness I like to dive in deep end. Hopefully studying comp sci in sept if I get my grades so maybe then ill be able to contribute to the forum a little better
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As for why, my device runs real smooth even at 500mhz but have a friend who likes to gloat over a cf bench result id like to smash, that and learning more and as much as I can on android OS.
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Related

Please help making a kernel

I was going to make a kernel based on cm7 kernel, so how to start.
And how to add frequencies.
Adding over clicked frequencies is the main purpose, please help me somebody.
I want to make it for HTC explorer but there are nearly no devs who can help me that's why I am asking here
Sent from my HTC EXPLORER using xda premium
> You can PM kernel experts.. like TA and DJnoXD.. they are both good persons and they could help you out.
I really appreciate your work. Few weeks back.. i was trying to convince every Forum Admins to get
Explorer and similar devices.. a forum or atleast a sub-forum.. and happy to see they accepted our request..
Being a Lagacy Device.. they gave Explorer and others a complete forum!!
rishabho1 said:
I was going to make a kernel based on cm7 kernel, so how to start.
And how to add frequencies.
Adding over clicked frequencies is the main purpose, please help me somebody.
I want to make it for HTC explorer but there are nearly no devs who can help me that's why I am asking here
Sent from my HTC EXPLORER using xda premium
Click to expand...
Click to collapse
if u have some prior coding experience then adding frequencies, adding governors should be a piece of cake...
if no,
then you better check the gb cm7 rom for optimus one..try to find out the commit where actual work was started by the cm team on the kernel..you will find out how they added frequencies, governors and everything...:good:
rr0yy said:
I really appreciate your work. Few weeks back.. i was trying to convince every Forum Admins to get
Explorer and similar devices.. a forum or atleast a sub-forum.. and happy to see they accepted our request..
Being a Lagacy Device.. they gave Explorer and others a complete forum!!
Click to expand...
Click to collapse
But, how is this related
Btw i also requested mikechannon to do so
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williamcharles said:
if u have some prior coding experience then adding frequencies, adding governors should be a piece of cake...
if no,
then you better check the gb cm7 rom for optimus one..try to find out the commit where actual work was started by the cm team on the kernel..you will find out how they added frequencies, governors and everything...:good:
Click to expand...
Click to collapse
That's nice idea of comparing with optimus one kernel
I'll try it.
Thanks for the tip
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Now I have some ideas but I am unable to extract the kernel from boot.img
I have cygwin and saw some guides about some perl script but I am unable to use it
Please guide me how to do it
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rishabho1 said:
Now I have some ideas but I am unable to extract the kernel from boot.img
I have cygwin and saw some guides about some perl script but I am unable to use it
Please guide me how to do it
Sent from my HTC EXPLORER using xda premium
Click to expand...
Click to collapse
u may use mDroidd's studio android....
rishabho1 said:
Now I have some ideas but I am unable to extract the kernel from boot.img
I have cygwin and saw some guides about some perl script but I am unable to use it
Please guide me how to do it
Sent from my HTC EXPLORER using xda premium
Click to expand...
Click to collapse
Check out dsixda kitchen. Extremely easy to use
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sellers86 said:
Check out dsixda kitchen. Extremely easy to use
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Click to expand...
Click to collapse
It's for making stock based roms
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Dude.. as Neko said why dont you talk to DJ and TA.. if you really want to learn about kernel
scripting and compiling??
rishabho1 said:
I was going to make a kernel based on cm7 kernel, so how to start.
And how to add frequencies.
Adding over clicked frequencies is the main purpose, please help me somebody.
I want to make it for HTC explorer but there are nearly no devs who can help me that's why I am asking here
Sent from my HTC EXPLORER using xda premium
Click to expand...
Click to collapse
I would suggest you to try compiling the cm kernel for your phone whitout changes. (cm wiki)
After you succeed compiling the kernel, test if it is working.
Now you have a base you could start working on.
Next step could be to change something. (frequencies for the p500 have to be changed here: arch/arm/mach-msm/acpuclock.c)

How to upgrade the kernel version to 3.xx?

hell_lock said:
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You upgrade a kernel version, by upgrading the kernel updates for that version.
lithid-cm said:
You upgrade a kernel version, by upgrading the kernel updates for that version.
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Can u elaborate sir?
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hell_lock said:
Can u elaborate sir?
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Click to collapse
It is pretty self explanatory.if you want a 3.0+ kernel, then merge a 3.0+ kernel into your source. Most aosp kernel track from the linux kernel. I am not going to get into the step by steps about it, that you can google.
lithid-cm said:
It is pretty self explanatory.if you want a 3.0+ kernel, then merge a 3.0+ kernel into your source. Most aosp kernel track from the linux kernel. I am not going to get into the step by steps about it, that you can google.
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But the 3.xx kernel sources are not released for my phone so what should I do?
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hell_lock said:
But the 3.xx kernel sources are not released for my phone so what should I do?
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Click to collapse
One of 4 things, Wait, merge from the linux kernel, merge from a 3.0+ device with similar hardware, or cry about it.
lithid-cm said:
One of 4 things, Wait, merge from the linux kernel, merge from a 3.0+ device with similar hardware, or cry about it.
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Click to collapse
I will choose option 3. Do u know what files should be changed?
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hell_lock said:
I will choose option 3. Do u know what files should be changed?
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Click to collapse
No, pending your source, and the other source, there are way to many different changes that could take place. I would use a tool like beyond compare and diff the folders to see what files are different, then based on your experience, start making changes, compile test, rinse and repeat.
lithid-cm said:
No, pending your source, and the other source, there are way to many different changes that could take place. I would use a tool like beyond compare and diff the folders to see what files are different, then based on your experience, start making changes, compile test, rinse and repeat.
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Click to collapse
I am ready to do that.. Can u tell me how can I reduce the chances of hard brick by doing this intensive testing?
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hell_lock said:
I am ready to do that.. Can u tell me how can I reduce the chances of hard brick by doing this intensive testing?
Sent from my GT-S5360 using XDA
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Click to collapse
Before you start working on it, nandroid backup your system. Its just the kernel, so you can always revert via recovery. Though you should already know that.
lithid-cm said:
Before you start working on it, nandroid backup your system. Its just the kernel, so you can always revert via recovery. Though you should already know that.
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Click to collapse
One wrong step in kernel can hard brick my phone right? Seniors in my forum have taught me not to mess with a kernel unknowingly cuz it has high chances of hard bricking the phone.
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hell_lock said:
One wrong step in kernel can hard brick my phone right? Seniors in my forum have taught me not to mess with a kernel unknowingly cuz it has high chances of hard bricking the phone.
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That is crap the kernel gets initialized during boot, unless your kernel is flashing a recovery as well, or your using a device without a dedicated recovery?
What do you mean by a dedicated recovery? I am using a samsung phone and we have a recovery mode and a download mode. We have both a permanent cwm and a zip fiw cwm(temporary).
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the dedicated recovery is a partition on is own, so lets say your mtd/emmc is structured like this
boot
recovery (this should be the dedicated recovery)
system
data
therefore you will be able to delete/flash/reflash the boot without affecting the tablet/system/other partitions
There are some devices that have a different recovery structure (tablets based on the rockchip soc)
Thanks for the help you both! I will learn more about partitions in my phone and come back on this thread.
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I guess most Samsung phones doesn't come as a recovery partition, it comes as an extra ramdisk as mentioned here.
Anyways I've flashed boot.img which I've compiled, and the first boot was a bootloop, of course. And after doing some changes, compiled again and flashed, and it was a success. So I don't think Kernels can hard-brick the device (IMO though).
For samsung...as long as you have download mode your in the clear...with download mode you can use Odin or heimdall to flash a working kernel or even stock software to return to stock.
Samsungs do not have a partition for recovery...its its own ramdisk..."recovery-ramdisk.img" so you can lose both recovery and boot with a kernel but with download mode and heimdall all you have to get is a working kernel with a working recovery, open terminal and type "heimdall flash --kernel kernelnamehere.includinganyfileextention" so "heimdall flash --kernel boot.img"
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You guys rightly said! We have a ramdisk included with a zImage in a boot.img. I have also seen cases where the recovery mode doesnt come but the download mode is still intact.
A guy from our forum once flashed a s2 kernel on my Y and he hard bricked it. No modes were opening on his phone but according to the theory given by you guys, atleast the download mode should have been working! Care to explain me why that happened? I think the same thing will happen with me when I use sources of other phone for my kernel.
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So what I read from this thread, if you don't have a recovery dedicated for your device you would hard brick it???
Coz I tried n tested some kernels
They didn't work out -but it was a soft brick
Not a hard brick
I had not made those
Now I'm willing to try once I get some hold on building kernels
And I have a Sony Xperia Neo V
It doesn't have stock recovery like Samsung so if I make or atleast try to make kernels on my own, would I risk my phone getting hard bricked???
Or just soft brick?
Ty for your time!
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[Q] what is Boot.img? noob here....

Hello.. can anyone explain to me what is BOOT.IMG? and this is improtant on flashing ROM?
I'm not sure what it is, but it somehow manages the boot process. Every ROM has its particular boot.img. it is needed, but it is included in all roms around here. So if you flash a rom via cwm, boot.img is flashed to your phone automatically. Why do you need to know?
Wow... Its the kernel. For the OP. For the other replier. Please dont give false information.
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Actually your both kind of right. A boot.img is a kernel smashed with a ramdisk. The kernel sets up internal hooks and initializations to the android os. The ramdisk contains a set of instructions and such to also create the hooks. In general a kernel is a binary image that contains all the drivers and such for a system to communicate with the hardware and the ramdisk initializes the hard ware
Please do not shoot people down. Some are just trying to be helpful.
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Edit. I mixed up my knowledge.
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[Q] Developers-Related question

Hi,
Im developing my kernel for Neo V. And after three days of soft bricking my neo v, i unbricked it with success to know and understand fully how flashtool works.
I have started sourcing and building but am still unsure of many things. Firstly, after building the kernel, may i ask how to build to boot.img? I dont seem to find a universal ramdisk source code but anyways it will be based on ICS. Please help if you know. Also, please preach me on making the boot.img work as it has failed me before in my previous works ive done privately.
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Toolchain also
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Tried searching for guides?on how to proceed further?
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brunomars said:
Hi,
Im developing my kernel for Neo V. And after three days of soft bricking my neo v, i unbricked it with success to know and understand fully how flashtool works.
I have started sourcing and building but am still unsure of many things. Firstly, after building the kernel, may i ask how to build to boot.img? I dont seem to find a universal ramdisk source code but anyways it will be based on ICS. Please help if you know. Also, please preach me on making the boot.img work as it has failed me before in my previous works ive done privately.
Sent from my GT-I9100 using Tapatalk 2
Click to expand...
Click to collapse
This might help you mate http://forum.xda-developers.com/showthread.php?t=1748297
Not these! i need to inject my zImage into the boot.img. doesent work even if i try. just does not flash. flashtool keeps failing.
brunomars said:
Not these! i need to inject my zImage into the boot.img. doesent work even if i try. just does not flash. flashtool keeps failing.
Click to expand...
Click to collapse
there is a bug in the semc S1 bootloader... sometimes if the boot.img isnt of a correct size then the device will not boot... the workaround is to add a "filler" file (which is say 512KB file with junk data) to the ramdisk so as to increase the size of the final boot.img file...
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Ghostfreak NB said:
there is a bug in the semc S1 bootloader... sometimes if the boot.img isnt of a correct size then the device will not boot... the workaround is to add a "filler" file (which is say 512KB file with junk data) to the ramdisk so as to increase the size of the final boot.img file...
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Shall add CWM
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Almost every custom kernel includes a recovery!
So you should as well do it!
Just my suggestion
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Check it out its out

Boot.img extract?

i want to extract a boot.img but everytime i try it doesnt get the ramdisk folder out.. is there a boot.img in which i can easily extract the zimage and ramdisk folder just using dsxdia's kitchen?
i cant seem to extract the zimage and ramdisk folder from any kernel?..
galaxys3lover said:
i want to extract a boot.img but everytime i try it doesnt get the ramdisk folder out.. is there a boot.img in which i can easily extract the zimage and ramdisk folder just using dsxdia's kitchen?
i cant seem to extract the zimage and ramdisk folder from any kernel?..
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Just use android kernel kitchen by Championswimmer. It is truly amazing and does the job very well.
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abcdjdj said:
Just use android kernel kitchen by Championswimmer. It is truly amazing and does the job very well.
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i tried .. it still says zimage not found.. can u please explain to me how to for example use kappa or lupus kernel into a rom?
i am creating a rom using stock .ftf file and i want to include a custom kernel into this rom.. how do i go about it??? please help?!
galaxys3lover said:
i tried .. it still says zimage not found.. can u please explain to me how to for example use kappa or lupus kernel into a rom?
i am creating a rom using stock .ftf file and i want to include a custom kernel into this rom.. how do i go about it??? please help?!
Click to expand...
Click to collapse
Oh no no. You are going the Samsung way I guess. In all Sony phones, we dont have a recovery partition. That means that we can't flash kernels from CWM. The only way is fastboot. So no way to include kernel in your rom zip file. Sorry. At the most you can only recommend users to use a particular kernel.
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abcdjdj said:
Oh no no. You are going the Samsung way I guess. In all Sony phones, we dont have a recovery partition. That means that we can't flash kernels from CWM. The only way is fastboot. So no way to include kernel in your rom zip file. Sorry. At the most you can only recommend users to use a particular kernel.
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OHHHH!!... but in the tutorial by nero young on how to build a custom rom .. he has a sk17i and he uses his own custom kernel when he builds the rom... http://forum.xda-developers.com/showthread.php?p=26283930
so if i cant use a custom kernel .. how do i extract the kernel.sin into the rom?
Basically you just can't flash kernel with the phone.
Usual practive in our phones is to include th boot.img in the rom file and ask it to be extracted and flashed via fastboot through pc.
Hope it helps
Don't know about the tuto
galaxys3lover said:
OHHHH!!... but in the tutorial by nero young on how to build a custom rom .. he has a sk17i and he uses his own custom kernel when he builds the rom... http://forum.xda-developers.com/showthread.php?p=26283930
so if i cant use a custom kernel .. how do i extract the kernel.sin into the rom?
Click to expand...
Click to collapse
You don't have to worry about the kernel when building a rom on stock rom. Just work on the system and you should have a proper working rom.
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abcdjdj said:
You don't have to worry about the kernel when building a rom on stock rom. Just work on the system and you should have a proper working rom.
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THANK YOU SO MUCH FOR YOUR HELP!!
so i just skip the step when he says i have to add a custom kernel... and not add any kernel at all??..
i mean should i atleast extract the kernel.sin into the working folder ..??
am using dsxdia's kitchen..
galaxys3lover said:
THANK YOU SO MUCH FOR YOUR HELP!!
so i just skip the step when he says i have to add a custom kernel... and not add any kernel at all??..
i mean should i atleast extract the kernel.sin into the working folder ..??
am using dsxdia's kitchen..
Click to expand...
Click to collapse
Yes. Kitchen requires a kernel for the working folder. Btw why do you need kitchen? If you need any help for developing your rom, just pm me.
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I am just learning ROM development.. and I saw this tutorial by Nero young and thought that was the way to do it .. what other way to do it??
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galaxys3lover said:
I am just learning ROM development.. and I saw this tutorial by Nero young and thought that was the way to do it .. what other way to do it??
Sent from my GT-I9300 using Tapatalk 2
Click to expand...
Click to collapse
Dude you can directly add root and busybox.and whatever you want. Check your pm.
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Hi,
You can use the attached META-INF folder. It has only the basic stuff like basic symlinks and permissions required for the rom to work properly. Just check the comments in the updater-script to know where to add your tweaks.
Good luck developing
abcdjdj

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