[Galaxy S II Android Development] Saber:
Troubleshooting

(Probably one of the most detailed troubleshooting guides for kernels on XDA)

Q: Why flash your kernel? - For new users of DorimanX kernel

This applies to dorimanx kernel in general. Dorimanx 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 dorimanx kernel! :)

Have a look at one of my posts on the thoughts on using my own kernel on neatrom (STOCK JB): http://xdaforums.com/showpost.php?p=63063198&postcount=23

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://xdaforums.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: What is the difference between v8.XX and v9.XX builds?

A: The 8.XX kernel branch was supposed to be the universal kernel that could be used for stock users and 4.2.X users as well as 4.3.X users. To be more specific, the 8.XX kernel branch has 2 GPU drivers for maliv1 and maliv2 roms, meaning that more ram needs to be allocated for the GPU. There isn't much of a performance difference using one or the other if you are on maliv2 rom, however one branch may get specific optmisations that are not present in others. In other words, choose the kernel version that you require, not the one that will support the most android versions. STOCK 4.1.2 users should use 8.XX builds, whereas 4.2.X and 4.3.X users should use 9.XX builds, depending on the ROMs mali (GPU driver) version.

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 sd cards don't mount after I flash dorimanX kernel!

A: Please check the format (or file system) of your sd cards. DorimanX kernel doesn't support ext4 formatted sd cards and hence you can't see them. You will need to format the sd cards to fat32 or other format.

Q: I came from a different custom kernel that used Stweaks, now the app has issues

A: Every time you come from a different custom kernel with stweaks support, make sure to wipe cache and dalvik cache after install dorimanx 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: How do I get a logcat for the kernel?

A: In stweaks, go to BUG-REPORT and tap on KERNEL-BUG.

Q: Why do I get bootloops with this kernel?

A: If you were on a working version on dorimanx kitkat before, there is probably something wrong with the installation. If you are on a ROM that is not kitkat, 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 DorimanX 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 beginners guide I made and then attempt to tweak the kernel using stweaks.

Q: How do I trim my partitions?

BEWARE: Make sure you have read all of the precautions before attempting to trim your partitions!

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: How do I use dual boot?

A: There are many guides on how to dual boot roms using dorimanx kernel. Just use the search function on XDA or GOOGLE it!

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: Why does the screen turn blank after the dorimanx logo appears during the boot process?

A: If your kernel doesn't bootloop, but the screen remains blank, there is a good chance that the ROM that you've used uses an older version of GPU drivers (Mali). This kernel only support ROMs with Maliv3 support. If you flash this kernel on MaliV2 or MaliV1 only roms, you will get a blank screen after flashing. To fix this, flash to the kernel the corresponds to your mali driver version and you should get your display back.

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: What is UBER?