[KERNEL][UNOFFICIAL]Gustavo Kernel builds by gsstudios - Galaxy S II Android Development

Unofficial Gustavo Kernel builds by gsstudios​(The resurrection of S2 kernels)​
The Background:
Gustavo kernel development has stopped for a while now. I've been a long term s2 user, but I felt that a lot of features need to be implemented into the kernel. As of a result, I decided to make my own personal builds! Please note that I'm no way as good as the master himself, Gustavo, but I try to implement features to the best of my abilities.
The Mission:
To continue giving support for the much loved kernel. New features and additions will be added to improve flexibility and speed to the already amazing kernel. My goal is to improve Gustavo kernel as much as I can, without sacrificing stability.
DISCLAIMER:
ONLY FOR AOSP BASED ROMS
I'm not responsible for bricked devices or wrong version flashing
You are using this kernel at your own responsibility
——— !!!!!!!! YOU HAVE BEEN WARNED !!!!!!!! ———
FEATURES:
This kernel includes the following additional features over stock Gustavo kernel:
- Built with Latest Optimized Linaro 4.9 Toolchain (Smooth, fast and fluid) - Main toolchain
- Trim support (Be careful if you have brickbug affected chip!)
- Updated FPBug fix is already included in this kernel!
THINGS TO DO:
- Why don't you tell me what to do
THINGS I WILL NOT ADD:
Code:
- LZ4 Compression (Our Boot partition is way too small to support this)
- Useless CPU governors such as Userspace
- Colour tuning support (Unless someone helps me with this)
- Recovery version (WIll only consider doing this if working on LP kernel)
- Higher thermal limits (We all know what happens if we do this)
- Higher overclocking/Lower underclocking capabilities (So you want less stability and more SODs?)
- Synapse support (Stweaks is the only app that can fully support this kernel)
- Linux Kernel version updates (My skills need to improve first before taking on something this big)
CREDITS:
Gustavo_s (Mastermind and creator behind Gustavo kernel)
gokhanmoral
codeworkx
Cyanogenmod
franciscofranco
AndreiLux (Synapse App)
hawkerpaul
Tungstwenty
faux123
myfluxi
neobuddy89
Lanchon (Music Bug Fix)
zeitferne (Music Bug Fix)
omni team
geeckodev
DOWNLOAD:
Refer to third post
CHANGELOG:
Refer to second post
KERNEL SOURCE:
Source code of the kernel can be found here:
https://github.com/gsstudios/android_kernel_samsung_smdk4412
ISSUES:
- All Gustavo kernel bugs
USEFUL LINKS
- CPU Governor and I/O Scheduler Guide
TCP Algorithm guide
HAVING PROBLEMS?
Read post 4 before posting questions!
GOT QUESTIONS?
Q&A Thread not up yet
HOW TO FLASH?
Check the troubleshooting guide
​
XDA:DevDB Information
Gustavo Kernel , Kernel for the Samsung Galaxy S II
Contributors
gsstudios, Gustavo_s
Kernel Special Features: See post 1
Version Information
Status: Testing
Created 2015-12-13
Last Updated 2016-07-01

---

Changelogs:
I understand that some people like Gustavo Kernel because it is simplistic with fewer options compared to DorimanX. I will attempt to make only important changes to the kernel, and no changes that are unnecessary.
For full changelogs, visit my repo: Github Link
--UNRELEASED VERSIONS (KERNEL UNDER TEST) --
Code:
[B]Gustavo Kernel xx/xx build[/B]
- Updated support for CM13
- Merged many updates from CM
- Built with Linaro 4.9 Toolchain
- TRIM is enabled by default
- Freezefix has been merged
- Isorec support has been added
- F2FS support
- ZRAM enabled by default
- General performance improvements and stability fixes
--RELEASED VERSIONS (GENERAL AVAILABILITY) --
Code:
Nothing to see here :)

---

Downloads
I test most of these builds to make sure they are stable. There may be some cases where I might not test out a build before releasing it. Kernels marked with '(STABLE)' are safe for everyday use, but only take this as a indication.
--IMPORTANT, PLEASE READ--
CAUTION: All builds marked with 'TRIM' at the end has TRIM enabled. If you have brickbug affected emmc chip, avoid downloading it if you don't know what you are doing! For more information about the trim brickbug, visit Lanchon's guide here: http://forum.xda-developers.com/gal...ives/rom-brickbug-aftermath-speeding-t2843238
All builds without 'TRIM' (marked as 'NON-TRIM') have trim disabled. These kernels are safe on brickbug affected chips.
MAKE SURE YOU'RE DOWNLOADING THE RIGHT KERNEL. OTHERWISE YOU COULD BRICK YOUR DEVICE!
For TRIM users:
To use TRIM, you can download an app on the app store called trimmer or use terminal commands as directed in the troubleshooting guide.
And finally, I always see the question on whether to use TRIM or NON-TRIM builds. I recommend using TRIM builds on all devices, even if you have brickbug affected chip. This is because TRIM builds are safe from brickbug as they have been correctly patched up and so it has been used by many users. However, when in doubt, use NON-TRIM builds.
Linaro or UBER
I have constantly changed between UBER and Linaro toolchains, and have stuck with UBER toolchain. Choose whichever you believe is best for you. UBER is just Linaro toolchain with extra patches and updated components for speed and smoothness improvements. Linaro is more simplistic and stable.
Main download link:
Download link will be added once kernel is working!
Mirror download link:
Download link will be added once kernel is working!​
Beta builds and stable builds will only be uploaded on AFH and github.

---

Troubleshooting
(Probably one of the most detailed troubleshooting guides for kernels on XDA)
Q: Why flash your kernel?
This applies to gustavo kernel in general. gustavo kernel is an aftermarket kernel (or custom kernel) that is designed to allow users to tweak their phone at the kernel or near-hardware level side of things. In other words, users get more fine-grained control over their phone, this includes overclocking, underclocking, changing behavior of CPU/GPU etc. Adjusting such settings isn't for the faint-hearted since there is soooo many things to understand, but you aren't required to understand all of the settings. Ultimately, if you want to improve your phone experience, try gustavo kernel!
Q:How do I flash your kernel?
A: You flash kernels like flashing roms, except you don't have to factory reset your phone. If you can't flash the kernel for some reason, you can either flash philz recovery then flash the kernel OR you can just make your own kernel .tar file and flash via ODIN by following this guide: http://forum.xda-developers.com/galaxy-s2/development-derivatives/convert-kernel-zip-to-tar-t2994381
Q: Which kernel version build should I flash?
A: Flash the latest stable version if you want the most stable experience. Builds that have not been marked with 'Stable' are mostly stable, or haven't been tested enough to earn a stable tag. Either way, it's up to you which one you want to flash. Read the changelog for any important changes that might have occurred in a particular build.
Q: Wifi doesn't work after I flash this kernel
A: There are two main causes to this issue, either there is a problem with your:
- Partitions OR
- Permissions OR
- Gapps OR
- ROM OR
- Compatibility with your wifi hardware
Don't use a pit with modded preload! It will just cause issues with ROMs and Kernels. Use stock pit or use a pit with unmodded preload. Sometimes, the gapps package you flash somehow breaks compatibility with the kernel. You can fix this by flashing a different gapps (making sure to clean cache and dalvik). If you have permissions problem, you can fix this by repartitioning your internal sd card or by reflashing back to stock rom. Sometimes, the ROM doesn't fully support the wireless drivers in the kernel, this can be solved by flashing a different ROM or different kernel. But if your wifi hardware is not compatible (a way to tell this is when you have tried everything and failed), there is nothing you can do but reflash the rom or flash a different kernel.
Q: My battery life sucks after flashing this kernel!
A: Download and install Betterbatterystats and see what is the culprit to your problem. If it is kernel related, have you made sure you have wipe cache and dalvik and reset stweaks settings? If yes, it would be nice if you posted a logcat.
Q: Why do I get bootloops with this kernel?
A: If you were on a working version on gustavo kernel lollipop before, there is probably something wrong with the installation. If you are on a ROM that is not lollipop, you flash the wrong kernel! You need to flash the right kernel for your android version. Sometimes, bootloops can occur due to corruption of the kernel zip file (usually from bad download) or from corrupted partitions.
Q: What do all of the settings mean? They are all confusing!
A: Please note that gustavo kernel isn't for users who have just rooted their device. Before jumping into the custom kernel world, try playing around with other kernels first. Once you think you have some experience, read the stweaks/synapse beginners guide I made and then attempt to tweak the kernel using stweaks/synapse.
Q: How do I trim my partitions?
BEWARE: Make sure you have read all of the precautions before attempting to trim your partitions!
A: install the trimmer app from the playstore. App link . Check for all 3 partitions, and tap on run. grant root access. the 3 fstrim operations should be successful ("partition was trimmed" means success).
alternatively, instead of using trimmer you can run one of these commands (these are better because they also trim /preload):
# on the phone in the terminal app:
su -c "fstrim -v /system; fstrim -v /data; fstrim -v /cache; fstrim -v /preload"
# on your PC if you are connected to the phone via adb:
adb shell su -c "fstrim -v /system; fstrim -v /data; fstrim -v /cache; fstrim -v /preload"
reboot.
Click to expand...
Click to collapse
Q: My device is (hard) bricked after flashing your kernel!
A: Have you read all of the precautions before installing the kernel? You made the decision to flash the kernel and now you've stuffed up your phone.
Q: I get constant FCs after flashing your kernel!
A: Have you wiped your cache partition, dalvik cache and reset stweaks settings? If you've done all of these already, a logcat would be nice
Q: What's a good combination for CPU governor and I/O scheduler?
A: Have a look at the default settings, they are optimised for our phone
However, here are some settings I personally like:
1. Governor: HYPER/Ondemand I/O scheduler:SIO/SIO
2. Governor: PegasusQ/Nightmare I/O scheduler: SIO/SIO
3. Governor: NeoX/Ondemand I/O scheduler: SIO/SIO
4. Governor: Nightmare/Nightmare I/O scheduler: SIO/SIO
Q: What is a TCP algorithm?
A: Congestion control strategies (or algorithms) are used by TCP, the data transmission protocol used by many Internet applications. The main goal of a TCP algorithm is to avoid sending more data than the network is capable of transmitting, that is, to avoid causing network congestion.
Q: Why not use XYZ toolchain?
A: See this post
Q: What is UBER?
A: After years of using different custom toolchains like Linaro and SaberMod, I found there were things I liked about both of them but also things that didn't sit quite as well with me. SaberMod always seemed to have UI lag (especially in scrolling) but opened apps well and Linaro always seemed to be buttery smooth but had terrible app opening speed. Linaro battery was also worse for me than SaberMod. After going back and forth between toolchains I finally had this epiphany! Why not just take all of the best parts of all toolchains and merge them into one? So I began bringing up my own toolchain from gnu.org. At first I patched in all of the AOSP toolchain pactches (much like how SaberMod did it originally however it is important that you realize that No! I did not copy and paste SaberMod into my source I'm simply stating that I used their idea of merging aosp into gnu.org) to my source. Then I went through and added all of the linaro patches that I could to the source. I also made sure that I had the very latest of every toolchain component. I then made very minimal changes to the aosp toolchain build folder to allow for building with these newer toolchain components and UBERTC was born!!! (Note: both Linaro and SaberMod both made lots of modifications to the toolchain build folder, UBERTC is the closest to the aosp build process)
Click to expand...
Click to collapse

---

Reserved post 4

---

Can't wait for this?
Will it support all Lollipop roms or just CM12?

---

NoctisBlade said:
Can't wait for this?
Will it support all Lollipop roms or just CM12?
Click to expand...
Click to collapse
CM12.1 for now. Hopefully Slimroms support later since all I have to do is slightly modify the ramdisk files. Much easier base to work with (compared to DorimanX kernel).
BTW, first builds is up. Haven't tested it yet but included only small changes from gustavo's last build. It features TCP algorithm changing support and updated toolchain. Expect more features to be added in the future.
regards, gsstudios

---

I've tested both with the latest cm12.1 build 11/12 and none of them boot past the Galaxy i9100 boot screen.
I cleared cache, installed, then rebooted.
Hope this helps!

---

y0.o! said:
I've tested both with the latest cm12.1 build 11/12 and none of them boot past the Galaxy i9100 boot screen.
I cleared cache, installed, then rebooted.
Hope this helps!
Click to expand...
Click to collapse
Thanks for confirming. Should only work on unofficial CM12.1. Doesn't work on official CM12.1.
OP will be updated.
Regards, gsstudios
Update: Build 13/12 has been demoted to 'alpha' because it only works on unofficial builds of cm12.1. Once it works on official cm12.1, the status of the project will change to beta. I'm taking a break now. Lots of hours trying to get certain changes to work, now I need a good rest.

---

Ahhh I see. The flash seems to have messed up my system after reflashing cm12.1 to gain the kernal back. For what ever reason I couldn't download anything, said there was no SD card.
My partitions are corrupt anyway, I always have to use this thread when ever I change OS http://forum.xda-developers.com/galaxy-s2/orig-development/repartition-memory-s2-t3018749 . I have no idea how to permanently fix it!
Reinstalling everything again ... Ahh well, one of the pitfalls of experimenting!
---------- Post added at 04:08 AM ---------- Previous post was at 04:04 AM ----------
gsstudios said:
Thanks for confirming. Should only work on unofficial CM12.1. Doesn't work on official CM12.1.
OP will be updated.
Regards, gsstudios
Update: Build 13/12 has been demoted to 'alpha' because it only works on unofficial builds of cm12.1. Once it works on official cm12.1, the status of the project will change to beta. I'm taking a break now. Lots of hours trying to get certain changes to work, now I need a good rest.
Click to expand...
Click to collapse
Sleep/rest well brother!

---

y0.o! said:
Ahhh I see. The flash seems to have messed up my system after reflashing cm12.1 to gain the kernal back. For what ever reason I couldn't download anything, said there was no SD card.
My partitions are corrupt anyway, I always have to use this thread when ever I change OS http://forum.xda-developers.com/galaxy-s2/orig-development/repartition-memory-s2-t3018749 . I have no idea how to permanently fix it!
Reinstalling everything again ... Ahh well, one of the pitfalls of experimenting!
---------- Post added at 04:08 AM ---------- Previous post was at 04:04 AM ----------
Sleep/rest well brother!
Click to expand...
Click to collapse
That's what happened also on the gustavo's build too. This will take lots of work to get it working on official CM12.1.

---

@gsstudios
What about kitkat ?
The kitkat kernel needs also an update (trim not working )
Thanks for building this kernel
Sent from my GT-I9100 using XDA Free mobile app

---

ajrajr155 said:
@gsstudios
What about kitkat ?
The kitkat kernel needs also an update (trim not working )
Thanks for building this kernel
Sent from my GT-I9100 using XDA Free mobile app
Click to expand...
Click to collapse
I will have to see. Gustavo only uploaded his lollipop kernel, not kitkat. So I guess I will have to search properly through his repo.
regards, gsstudios

---

are "BLN" and "slide to wake" working?

---

cikenkari said:
are "BLN" and "slide to wake" working?
Click to expand...
Click to collapse
The kernel isn't even working on CM12.1 official yet. BLN and Slide to wake isn't top priority yet. I think I will have to close this thread until I release a 'working kernel'. Sorry for this "hype", was so close to bringing back gustavo kernel from the dead.
regards, gsstudios

---

Hey guys,
It has been a while since my last attempt with gustavo kernel.
Just letting you guys know that while dori kernel seems to be plagued with selinux issues, I will be aiming to get this kernel working on CM13.
Edit: So it has been discovered that selinux isn't the main problem we're facing in dori kernel, but we seem to be having other issues.
Currently, it is stuck on CM boot animation and won't go past. Selinux is alive and we have proper adb working which will aid us in the development. There is no guarantee that we will see a working MM kernel (I've only been working on the kernel for about 1 day )
gsstudios

---

gsstudios said:
Hey guys,
It has been a while since my last attempt with gustavo kernel.
Just letting you guys know that while dori kernel seems to be plagued with selinux issues, I will be aiming to get this kernel working on CM13.
Currently, it is stuck on CM boot animation and won't go past. Selinux is alive and we have proper adb working which will aid us in the development. There is no guarantee that we will see a working MM kernel (I've only been working on the kernel for about 1 day )
gsstudios
Click to expand...
Click to collapse
Big big thanks @gsstudios, your work and efforts are welcome, count with me to test your kernel, Gustavo's works great in LP hope you can take to MM soon [emoji6]
S2 Cyanogenmod 6.0.1 [official nightly] - arnab isorec twrp - Xposed [official framework]

---

All in impatience. Great news. Since dorimanx have problems with memory, I hope it will allow the kernel to wait for the elimination of unpleasant bug. Thank you, gsstudios.

---

gsstudios said:
Hey guys,
It has been a while since my last attempt with gustavo kernel.
Just letting you guys know that while dori kernel seems to be plagued with selinux issues, I will be aiming to get this kernel working on CM13.
Edit: So it has been discovered that selinux isn't the main problem we're facing in dori kernel, but we seem to be having other issues.
Currently, it is stuck on CM boot animation and won't go past. Selinux is alive and we have proper adb working which will aid us in the development. There is no guarantee that we will see a working MM kernel (I've only been working on the kernel for about 1 day )
gsstudios
Click to expand...
Click to collapse
Hi sir! What is the difference of gustavo and dorimanx? TIA

---

KnightElf009 said:
Hi sir! What is the difference of gustavo and dorimanx? TIA
Click to expand...
Click to collapse
Gustavo kernel code base is much closer to cyanogenmod kernel. DorimanX kernel was based off Siyah kernel a long time ago, and has a lot more changes. Dorimanx kernel is still being maintained, while Gustavo kernel is dead (I have paused development in favour of dorimanx development).
gsstudios