# Kexec - Custom Kernel Support



## JuggalotusHeat (Jul 20, 2011)

Just to share the love:

http://www.epiccm.or...urce-built.html


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## GarryLumpkins (Jun 14, 2012)

Holy cow that was fast!


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## deitiphobia (Nov 19, 2011)

http://forum.xda-developers.com/showthread.php?t=1760678

This is their post on XDA about the kexec custom kernel support for Verizon Galaxy S III.


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## GarryLumpkins (Jun 14, 2012)

To add on to this noobnl said that he cracked the RIL (to my knowledge is the radio) which opens the door to Jelly Bean goodness!


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## trendsetter37 (Aug 16, 2011)

GarryLumpkins said:


> To add on to this noobnl said that he cracked the RIL (to my knowledge is the radio) which opens the door to Jelly Bean goodness!


Ho ho hoooly shite! I'm jelly beaning pants!

Sent from my trusty thunderbolt


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## siff (Aug 26, 2011)

Too funny.....


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## junjlo (Oct 1, 2011)

so how does this work every time i reset i have to go in recovery to start my phone?


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## AzJazz (Jun 10, 2011)

GarryLumpkins said:


> To add on to this noobnl said that he cracked the RIL (to my knowledge is the radio) which opens the door to Jelly Bean goodness!


Rumors are that Samsung upgraded hardware in the GS3 to "future-proof" for Jelly Bean. (http://www.theverge.com/2012/6/27/3121569/galaxy-s-iii-variants-ram-upgrade-jelly-bean).

I would expect Samsung to be updating the GS3 for JB anyways ... It's not nearly as big a leap from ICS to JB as it was from GB to ICS.

I am not worried about JB coming to the SGS3.


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## deitiphobia (Nov 19, 2011)

AzJazz said:


> Rumors are that Samsung upgraded hardware in the GS3 to "future-proof" for Jelly Bean. (http://www.theverge....rade-jelly-bean).
> 
> I would expect Samsung to be updating the GS3 for JB anyways ... It's not nearly as big a leap from ICS to JB as it was from GB to ICS.
> 
> I am not worried about JB coming to the SGS3.


Well most certainly the GS3 will get Jelly Bean from Samsung eventually, but that will be months from now. The Devs can do that in a matter of weeks.


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## nbsdx (Jul 6, 2011)

This is very exciting. I knew that there was work being done on a kexec port, but I didn't know it was this far along. Bravo devs! =D


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## djd338 (Feb 3, 2012)

deitiphobia said:


> Well most certainly the GS3 will get Jelly Bean from Samsung eventually, but that will be months from now. The Devs can do that in a matter of weeks.


2 GB ram is fantastic and is the "futureproof" thingy Sammie put in the sgs3 looking toward JB. But, by the time POS-Verizon gets around to their version of JB the hardware will be worn out. F'em. I throw my full support to these great devs, and whatever I can do to remove all reference of POS-Verizon from my phone, I will immediately do.


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## Austin (Jul 4, 2012)

Explain this to me like I'm five...

Sent from my DROIDX using RootzWiki


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## nbsdx (Jul 6, 2011)

Austin said:


> Explain this to me like I'm five...


Do you know how second init works for droid x? it's kinda sorta not really similar. Basically, since we can't flat out replace the kernel because of Verizon's signing BS, we have to "trick" it. It boots into a stock kernel that (If i understand correctly) has support for kexec (kexec is a magic program that lets you replace the running kernel with another one). The problem then is that the hardware drivers have to be stopped for kexec to take place, and they can't be started back up without going through the bootloader (because nothing can be easy right?). So, (and this is where I start to lose track of what's going on) when kexec is ran, a new kernel is pointed to by the user, and then resets to the bootloader which restarts the hardware drivers, and boots the custom kernel.

tl;dr Kexec is black magic that is cool as hell.

Edit: I'm not exactly sure how it accepts the new kernel if it's not signed - i assume that signature check occurs before the bootloader (which seems weird to think about... and doesn't make a lot of sense from an Operating System / Hardware Architecture standpoint - idk )


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## JuggalotusHeat (Jul 20, 2011)

GarryLumpkins said:


> To add on to this noobnl said that he cracked the RIL (to my knowledge is the radio) which opens the door to Jelly Bean goodness!


This is correct. He got it "cross paltform" style for the specific radio/chipset. It has also been approved and merged into CM via Steve.


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## JuggalotusHeat (Jul 20, 2011)

Quick Update...I think we might see CM9 before it even hit's store shelves. I'll keep you posted







)


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## jdhas (Jun 14, 2011)

JuggalotusHeat said:


> Quick Update...I think we might see CM9 before it even hit's store shelves. I'll keep you posted
> 
> 
> 
> ...


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## nbsdx (Jul 6, 2011)

nbsdx said:


> Do you know how second init works for droid x? it's kinda sorta not really similar. Basically, since we can't flat out replace the kernel because of Verizon's signing BS, we have to "trick" it. It boots into a stock kernel that (If i understand correctly) has support for kexec (kexec is a magic program that lets you replace the running kernel with another one). The problem then is that the hardware drivers have to be stopped for kexec to take place, and they can't be started back up without going through the bootloader (because nothing can be easy right?). So, (and this is where I start to lose track of what's going on) when kexec is ran, a new kernel is pointed to by the user, and then resets to the bootloader which restarts the hardware drivers, and boots the custom kernel.
> 
> tl;dr Kexec is black magic that is cool as hell.
> 
> Edit: I'm not exactly sure how it accepts the new kernel if it's not signed - i assume that signature check occurs before the bootloader (which seems weird to think about... and doesn't make a lot of sense from an Operating System / Hardware Architecture standpoint - idk )


Here's a post that clears some of my confusion up: http://forum.xda-developers.com/showpost.php?p=28484191&postcount=262


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## E Sini (Mar 15, 2012)

Does anyone have an update on this? Are there official validations that there's a work around to the boot loader and custom kernels being installed? I never used IRC so I haven't really been looking there. Unless someone can help me get to the chat.

Sent from my Galaxy Nexus using Tapatalk 2


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## nbsdx (Jul 6, 2011)

E Sini said:


> Does anyone have an update on this? Are there official validations that there's a work around to the boot loader and custom kernels being installed? I never used IRC so I haven't really been looking there. Unless someone can help me get to the chat.


There is a thread over at XDA about it that has a link to the dev's blog. The link in my previous post has a bit more info too. The downside to the kexec method as of right now is that you have to overwrite the recovery partition with a modified kernel that supports kexec, and that boots the custom kernel (AFAIK).


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## PhantomGamers (Sep 27, 2011)

nbsdx said:


> There is a thread over at XDA about it that has a link to the dev's blog. The link in my previous post has a bit more info too. The downside to the kexec method as of right now is that you have to overwrite the recovery partition with a modified kernel that supports kexec, and that boots the custom kernel (AFAIK).


Sounds good, I hope we figure something out that DOESN'T require overwriting the recovery though...
Unlikely I suppose.


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## nbsdx (Jul 6, 2011)

Obviously that would be ideal, but I'm assuming that we can push the old recovery back on if it screws up - it wouldn't make sense if we couldn't. But it proves that it is possible.


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## J_Dav1 (Sep 20, 2011)

Hopefully well only have to deal with this for a little while. Hopefully someone will be able to find the signature check in the bootloader code and remove it.

Sent from my Transformer Prime TF201 using Tapatalk 2


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## nbsdx (Jul 6, 2011)

J_Dav1 said:


> Hopefully well only have to deal with this for a little while. Hopefully someone will be able to find the signature check in the bootloader code and remove it.


I think it's a bigger problem than that. Replacing the bootloader isn't the safest option... This is generally because you have to be in the bootloader to flash anything to the device. So if you want to replace the bootloader, you more than likely will have to take the phone apart and program it manually using a JTAG cable (Not something a normal, or even semi-experienced user would want to do). There was a thread floating around XDA where they were talking about trying to crack the signature, but that would take a very very long time, even with the strength of modern GPUs (partly because I don't think it's known exactly what is being checked - i'm sure someone does, I sure as hell don't though).

So for now, it looks like we just have to wait for a roundabout way unless you feel like replacing your recovery partition *shrug*

**DISCLAIMER** this is all speculation - I haven't had time yet to screw around with it, I just got it yesterday. I most certainly will be looking into some of this ASAP though


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## E Sini (Mar 15, 2012)

http://www.idigitaltimes.com/articles/10254/20120710/samsung-galaxy-s3-verizon-bootloader-unlocked-code.htm

Check this out.. source code for the locked boot loader. Can any Dev use this to get it done??

Lol I'm posting this everywhere to try to get this circulated and hopefully we can get some help here

Sent from my Galaxy Nexus using Tapatalk 2


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## PhantomGamers (Sep 27, 2011)

E Sini said:


> http://www.idigitalt...locked-code.htm
> 
> Check this out.. source code for the locked boot loader. Can any Dev use this to get it done??
> 
> ...


I replied when you posted this before: this is NOT the bootloader source code.


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## nbsdx (Jul 6, 2011)

E Sini said:


> http://www.idigitalt...locked-code.htm
> 
> Check this out.. source code for the locked boot loader. Can any Dev use this to get it done??
> 
> ...


Also, this has been known for a while - it's the reason that the custom recovery kernel exists


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## JuggalotusHeat (Jul 20, 2011)

nbsdx said:


> Obviously that would be ideal, but I'm assuming that we can push the old recovery back on if it screws up - it wouldn't make sense if we couldn't. But it proves that it is possible.


We can definitely push the stock recovery back on if it goes nuts.


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## nbsdx (Jul 6, 2011)

Figured as much - just making sure. thanks!


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## JuggalotusHeat (Jul 20, 2011)

nbsdx said:


> Figured as much - just making sure. thanks!


no problem


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## JuggalotusHeat (Jul 20, 2011)

and a lil' more love:

https://github.com/CyanogenMod/android_device_samsung_d2vzw


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## mds96 (Dec 24, 2011)

JuggalotusHeat said:


> and a lil' more love:
> 
> https://github.com/CyanogenMod/android_device_samsung_d2vzw


 Spank my ASS, THIS IS EXCITING!! lmao....So I'm a noob to git...Is there something flashable yet?? Lol. I want this TW off my damn phone! Lol


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## nbsdx (Jul 6, 2011)

You don't want to flash it. Did you miss the readme? It's still HIGHLY experimental. TW is probably better at this point. I have Apex launcher installed for now and that helps a ton lol

"WORK IN PROGRESS. WILL EAT YOUR CAT."


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## mds96 (Dec 24, 2011)

nbsdx said:


> You don't want to flash it. Did you miss the readme? It's still HIGHLY experimental. TW is probably better at this point. I have Apex launcher installed for now and that helps a ton lol
> 
> "WORK IN PROGRESS. WILL EAT YOUR CAT."


 Yep missed it, lol. Probably just too excited! Yeah I'm using NOVA, and it does help!!


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