[Galaxy S II Original Android Development] Entropy512:
Read the Known Issues section of this post below along with the FAQ a few posts down before posting.

A few people have asked about I9100 builds of my Daily Driver kernel for the SGH-I777. I normally hate blind development, but since most I9100 guys are doing it for I777 targets, I may as well try going the other way. Since it fails the definition of being a "daily driver" as I own an I777 and not I9100 - it will not be using the Daily Driver name.

This should be compatible with most stock-derived Gingerbread firmwares, with a few exceptions listed below. It is NOT compatible with CM7/MIUI or any other AOSP-derived firmware. It is NOT compatible with ICS and WILL NOT BE until ICS kernel source for the I9100 is released. At that point a new thread will be created for those kernels. I am testing it currently with self-deodexed/debloated/Hellraised XWLA4.

The following firmware bases are likely to deliver poor battery life with this kernel due to wifi bugs in the firmware:

XXKI3, UCKK6, XWKK5 - especially UCKK6 and XWKK5

This kernel series is intended to be similar in spirit to my Daily Driver series for the Infuse at http://xdaforums.com/showthread.php?t=1212795

It is built from sources at https://github.com/Entropy512/linux_kernel_sgh-i777/commits/oc_codeworkx, and initramfs at https://github.com/Entropy512/initramfs_sgh-i777/commits/master

My general goals are to focus on stability and battery life. If it comes to a tradeoff between performance and the above two, I will choose stability/battery life. In general I will choose stability first, with the exception of undervolting.

I keep my initramfs clean - There are no tweaks or other automated scripts built into this kernel. For a collection of tweaks I am working on and documentation on them, see http://xdaforums.com/showthread.php?t=1378080

Current features:

I9100 Update3 base

Touchscreen drivers from I777 source code base

codeworkx's cpuidle patch - should improve battery life a bit. In most cases it will likely not improve things much, but in rare cases it will result in significant improvements. (I only have one partially-reproducible test case on the Infuse so far)

JHash 3

BFQ I/O scheduler

CIFS module in initramfs

CWM 5.0.2.8 compiled from CM7 sources on 2/28/2012

"insecure" kernel (meaning root in ADB)

CPU governor set to Conservative by default to conserve some battery - this will make your device slightly less responsive, use SetCPU or a similar app to return to ondemand if you want it, or reduce the conservative polling interval

Filesystem readahead tweaks in initramfs

netarchy's Sleep of Death fix

netarchy's conservative governor tuning patch - should improve responsiveness of devices when using the conservative governor if you reduce the polling interval (misnamed as sample_rate) - the I9100 community calls this "lionheart" even though it's really only a 2-line patch

Battery charge current monitoring (CurrentWidget) support - only reports charge current and not discharge, and reports a value 2.85 times the actual current. Use CurrentWidget's "operation on value" to divide by 2.85.

Miscellaneous bugfixes pulled from Ninphetamine and CM7 sources - see github for details

/system/etc/init.d support in initramfs - Note that this only runs stuff in /system/etc/init.d - ROM developers or you need to create it. Attached is an example script that will change the CPU frequency governor to ondemand if placed in /system/etc/init.d and set to executable

Four "use at your own risk" features that trade performance for stability - See Post #4 for details

Standard bootanimation support

/proc/last_kmsg crash debugging support

NFS modules in initramfs - note that they must be insmodded in a specific order: sunrpc.ko, lockd.ko, then nfs.ko

Fix for fuel_alerted perma-wakelocks

Fix for wifi tethering on I9100 ROMs that have been Hellraised to I777

Bump up TCP buffer sizes in initramfs to match that of the Infuse - may help network performance in some cases

cpuidle driver from Tab 7 Plus kernel - allows entry into AFTR more often - includes MFC interoperability fix (Should not break video playback.)

Support Bluetooth HID on newer firmware bases

3-step GPU clock/voltage control

Extended hotplug tuning

Support for Xan's ExTweaks universal tuning app - https://market.android.com/details?id=com.darekxan.extweaks.app

Planned features, short term:

Determine if issues with PINlock when running I9100 firmwares on I777 have kernel involvement, and fix them if this is the case.

Planned features, mid-term:

Potentially my first departure from "standard" governors, with a focus on improving hotplugging logic

Planned features, long-term:

Improved battery charge algorithm for faster charging - Initial research indicates we have an alternate battery charger chip (MAX8922) that differs from the MAX8997 used in the I9100. We DO have an 8997 also - but on our device for some reason Samsung decided to use an alternate chip instead of using the 8997's built-in charging. This means we have far fewer options (90,400,660 mA) in terms of charge rates compared to the I9100 (from 200 to 950 in 50 mA steps). So we might not be able to implement any fancy charging algorithms. :(

Features not planned:

BFS process scheduler - I have only once ever seen a test case where this clearly outperformed the mainline Linux scheduler (multithread x264 encoding) - The mainline schedule was fixed in the next release and BFS now has no performance benefits

Any feature that trades off stability or data integrity for performance unless it can be disabled entirely and defaulted to "off"

Any feature that cannot have functionality tested without a paid app. Interface-only checks don't cut it - I don't want users complaining that the app they paid for didn't work because an interface check worked but function didn't

Touch recovery - too prone to unintentional user input in dangerous situations. I will reconsider this with ICS.

ARM_TOPOLOGY/SCHED_MC - See http://xdaforums.com/showpost.php?p=23193259&postcount=100 for details

Known issues:

Power management regression somewhere between 12/8/11 and 1/2/12 - Intermittent high drain without high AOS or reduced deep sleep percentage when on some wifi networks - seems more likely if GPS is used when connected to wifi. Wifi with high AOS/reduced deep sleep is not a kernel problem. This appears to only happen on some firmwares - it happens on XXKI3 but not XWKL1. It is likely connected to a wifi power management bug in some firmwares. A debugging feature in 2/7 and later will allow identification of such firmwares - see http://xdaforums.com/showpost.php?p=22581928&postcount=1777 for details

Some people have reported touchkey lights becoming disabled until the screen is turned off and back on again. Under investigation - seems to mainly happen on firmwares with BLN-modded liblights even if the BLN app isn't used

Internal and External SD card are swapped in CWM currently

Keymap is a little funky in CWM for I9100 users. VolUp/VolDn to move, Power to select is reported to work, but bottom keys are funky. Working on it

A few users have reported that when Hellraising I9100 firmwares to I777, they are unable to set up a PIN-lock. If this occurs for I9100 users on their own devices, I need to look into initramfs fixes and this will be my top priority.

Basic flashing instructions for .tar releases (NOTE - There are currently no releases in this category. These instructions only remain for heimdall+ZIP users:

(Tested on Linux, not tested MacOS/Windows but should work) Heimdall - Extract the contents of the tar file, enter download mode, and flash with the following command line:

heimdall flash --kernel zImage

Flashing instructions for .zip releases:

Flash in CWM, or extract the zImage and use the Heimdall instructions above.

Please do not ask how to enter download mode or install Heimdall/Odin in this thread - these are basic generic skills anyone flashing custom firmwares on Samsung devices should know and plenty of documentation exists elsewhere. If you really need to ask, use the General forum, or if created, the Q&A forum. I want to try to keep this thread clean and only with bug reports and issues specific to this release, not general HOWTO or troubleshooting posts. Some of the information you need is in jivy26's FAQs thread at http://xdaforums.com/showthread.php?t=1288112 - Reading at least the first post of this thread in its entirety is STRONGLY recommended.

Bug reports:

If you have a crash (reboot all the way to Galaxy S I9100 screen), use ADB dump the contents of /proc/last_kmsg and post

If you have oddball behavior, include a clearly reproducible test case with your report, or use ADB to obtain a dmesg and logcat capturing the odd behavior at the time of error.

Similar to flashing - using ADB and obtaining last_kmsg, dmesg, and logcat dumps are basic skills that anyone working with custom firmwares on Android devices should have. If you need help with these, do some searching, or post in the General forum or Q&A forum.

Firmware ("ROM") Developers:

While I cannot restrict anyone from putting this kernel into a ROM as long as links are given to the github sources for GPL compliance, I request that anyone who includes this kernel in a firmware release does the following out of courtesy:

Link to this thread

Clearly indicate in your firmware changelog which Daily Driver kernel release is included in your firmware release whenever you change DD releases - this lets users identify whether a fix is present in the kernel they're using or not

Kernel Developers:

Similar to my request for ROM developers, while I can't restrict you from doing anything, I ask as a courtesy that if you cherry-pick my commits, you do the following:

Please don't rebase my commits into a large multi-feature without consulting me - rebasing related bugfixes together is OK.

Please try not to implement lots of unrelated features or bugfixes in a single git commit - it makes it hard to reimplement that when Samsung drops new sources or releases a new device

ALL OF MY RELEASES ARE NAMED BY RELEASE DATE - MMDDYYYY. See the changelog for differences between Experimental (exp) and non-exp versions for days where dual releases are made.