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Kexec, and a Proof-of-Concept Source-Built Kernel (Bootloader Workaround)

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By CMTeamEpic, Retired Recognized Developer on 9th July 2012, 07:23 AM
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Team Epic announces a proof-of-concept source-built kernel for the Verizon SGS3, complete with kexec hardboot support. This kernel serves two purposes:

1. To be included in custom recovery images, as it proves the capability of booting-via-kexec custom kernels from recovery.

2. To serve as a proof-of-concept boot kernel, to demonstrate that custom kernels are capable of running on the Verizon SGS3 in its present form.

Please see our blog post, Kexec, and a Proof-of-Concept Source-Built Kernel for the Verizon SGS3, for full details and source links.

CyanogenMod's Team Epic specializes in Sprint's flagship Android phones on Sprint.
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9th July 2012, 07:25 AM |#2  
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Awesome! Thank you so much for your guys efforts

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9th July 2012, 07:35 AM |#3  
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Good luck guys.

☞ sent from my GS3
9th July 2012, 07:43 AM |#4  
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Just to confirm, the kexec hardboot approach used here is a bit different from the typical kexec. The main difference is that we actually perform a hardware reboot, reinvoking the bootloader just prior to booting the kexec'd kernel.

The advantage to this approach is that it maintains a high-degree of compatibility and minimizes buggy behavior. The disadvantage is that it requires that the bootloader is capable of booting custom recoveries, which the present Verizon SGS3 bootloader is capable of doing.

Thus, it's very important that folks do not apply any over-the-air (OTA) update, until it is confirmed that custom recovery booting remains intact.

If it eventually arises that booting from a stock kernel/recovery is necessary, then it's likely a bunch of kernel bugs will have to be fixed, and it might still have compatibility issues observed in previous kexec attempts. It's linked in the blog post, but there's a bit more of a technical description of the hardboot approach in this old thread.

Thanks to invisiblek and captjtkirk for testing.
Last edited by mkasick; 9th July 2012 at 07:53 AM.
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9th July 2012, 07:51 AM |#5  
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you guys are awesome xda has the best devs ever! I worship you guys!
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9th July 2012, 07:58 AM |#6  
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Wow! Thanks for taking the time to do this even though you guys aren't vzw owners. Great example of how great this community is.

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9th July 2012, 08:12 AM |#7  
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Unbelievable...you guys are awesome.

Jelly Bean here we come!

9th July 2012, 08:42 AM |#8  
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Quote:
Originally Posted by mkasick

Thus, it's very important that folks do not apply any over-the-air (OTA) update, until it is confirmed that custom recovery booting remains intact.

Forgive my paranoia, but does Verizon have the ability to force an OTA without us pressing an "OK" button?

Thanks to all who worked on this, you're awesome!
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9th July 2012, 09:13 AM |#9  
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Quote:
Originally Posted by jh120

Forgive my paranoia, but does Verizon have the ability to force an OTA without us pressing an "OK" button?

Thanks to all who worked on this, you're awesome!

nope. you have to accept the OTA
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9th July 2012, 09:17 AM |#10  
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Just a question does the kexec allow the sgsiii to use both cores. I have heard that kexec on both the droid razr and droid 3 doesn't allow for dual core yet. Any such issues with sgsiii or is it too soon to tell?


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9th July 2012, 10:29 AM |#11  
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Quote:
Originally Posted by Neverendingxsin

nope. you have to accept the OTA

Depends. My rezound didn't ask. I would wake up with my phone in recovery. It would fail to install the update because the stock recovery wasn't there but it never gave me a choice to install or refuse

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