[Kernel][5.1] M-Kernel - a76/77 [WiFi/3G] [f2fs/ext4] [5/14/15]

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Senior Member
Nov 21, 2012


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Senior Member
Nov 21, 2012
How do you correctly flash it to the tablet? :confused: I tried to flash boot.img via flashboot, but the Nexus won't boot anymore. I restored the original boot.img from the CM11 Image.

Probably it's written somewhere in the past 500 pages.. :eek:

As long as you have an Alpha 4.4 - (from OP) or just a KitKat ROM and a TWRP recovery is simple by rebooting to the recovery and install the flashable zip as it is. I did the same with 4.4.4 (KTU84P, "nakasi" for Nexus 7 (Wi-Fi)), unrooted it and installed a custom recovery with the help of Wug's Nexus Root Toolkit.
But it is your own risk to do it. I have grouper and already made a back up of my nvflash blobs just in case...
Good luck.


Senior Member
Jun 13, 2011
As long as you have an Alpha 4.4 - (from OP) or just a KitKat ROM and a TWRP recovery is simple by rebooting to the recovery and install the flashable zip as it is. I did the same with 4.4.4 (KTU84P, "nakasi" for Nexus 7 (Wi-Fi)), unrooted it and installed a custom recovery with the help of Wug's Nexus Root Toolkit.
But it is your own risk to do it. I have grouper and already made a back up of my nvflash blobs just in case...
Good luck.

I have TWRP and already tried to flash the .zip, just like a new Rom or Gapps. The console's messages say "all done", but the kernel won't get updated :(

I flashed the boot.img with flashboot getting around twrp.. nope!


Senior Member
Nov 21, 2012
I have TWRP and already tried to flash the .zip, just like a new Rom or Gapps. The console's messages say "all done", but the kernel won't get updated :(

I flashed the boot.img with flashboot getting around twrp.. nope!
If you read few pages back there is a workaround. Download TWRP 2.8.3 img for your N7 from TWRP site. Boot to your recovery and if you have a version above 2.8.4 then you can install a recovery img directly. Just be careful to choose recovery and not bootloader... After a successful installation reboot to the recovery, install the kernel, clear dalvik and cache.
Just, worked for me. and now shows the right kernel information.

Sent from my TF700T using Tapatalk

Charles IV

Senior Member
Jan 15, 2016
@Metallice thank you very much for this kernel, and when i was on stock, i found it really useful and amazing. Unfortunately, I am now running aaopt's Lineage OS 14.1 rom and wanted to be able to undervolt my kernel, however i could find extremely few guides to build a kernel with this.
Following a guide here for another device i started modifying the kernel source, however too much of it is different or not applicable, and all i could find is adding metallice_grouper_defconfig and motley_grouper_defconfig in arch/arm/configs.
I imagine this aren't magically included automatically, but i couldn't find where to include them.
I hope you could point me in the right direction, and i would be very grateful.
What I've done so far is here on github (ads-7.1.0-mod branch) and i dont mind if i only include overclocking and undervolting, or all m-kernel features.
I have been editing/replacing many files, generally by looking through the metallice_grouper_defconfig history and editing/replacing files also edited in commits affecting the defconfig.
I am updating the ads-7.1.0-modable branch every now and then, even if builds are failing.
I am having trouble building, and any support on which files to edit/how to edit and troubleshooting build errors would be greatly appreciated
Last edited:


Jan 18, 2020

Hi, hope its ok to post in an old thread,

i've just been playng with roms and kernels on an old grouper for my kid to use

i'm using ROM][All-F2FS]KitKat 4.4.4 KTU84P stock odex All-F2FS

i've got it all setup and running with mkernel a69 nd seems ok but when i do about phone it says 'dirty' at the end of the kernel name

i'm using the latest bootloader and twrp 2.7.00 (one for f2fs from another thread for slimkar f2fs etc)

is this ok/normal?



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    Page 1: Information
    Page 2: Changelog and Downloads
    Page 3: Additional info and FAQ


    Make sure you are on the latest bootloader version before flashing this or any other custom kernel. Search for a flashable zip or use fastboot and the google factory images.

    Download Kernel to internal SD card. Flash in recovery. Reboot. Congratulate yourself for wisely installing the best nexus 7 kernel. ;)

    A complete list of changes is available at my Github.
    Source: https://github.com/Metallice/android_kernel_grouper

    Recommended Settings:

    The only app supported for changing any kernel parameters and settings is TricksterMod - https://play.google.com/store/apps/details?id=com.bigeyes0x0.trickstermod

    CPU governor - TouchDemand with default parameters (default)
    I/O Scheduler -
    - ROW for pure read speed. Fast reads which are often the most important on mobile. Similar concerns like deadline.
    - BFQ for more consistent performance. Slower than Deadline and ROW, but prevents stutters while downloading in background
    Max Frequency - 1.2Ghz (Stock max for 2+ cores) (for lollipop it might be a good idea to use 1.3Ghz)
    - Note: Tegra sets the max frequency to 1.5Ghz at boot, make sure to change it manually or have an app set it at boot to avoid battery loss. If you have a program such as
    TricksterMod set it at boot make sure to include at least a 60 second "delay" in applying boot settings.
    - Note 2: DO NOT USE THE APP "SYSTEM TUNER" TO SET FREQUENCIES. CONFLICTS WITH AUDIO PERFLOCK IN KERNEL. Do NOT use system tuner to set frequencies as it conflicts with audio performance lock in this kernel. Will prevent you from lowering your maximum frequency. Use Trickstermod.
    GPU Max Freq - 446Mhz (maintains good battery life while smoothing out some games. Anything greater than 446Mhz is so heavily bottlenecked by RAM that it's essentially worthless. 600Mhz might give you 1 or 2 extra FPS for significantly worse heat, battery life, and stability)
    - Possible frequencies - To be completed later
    Fsync - On
    Dynamic Fsync - On (be aware of data loss concerns, even if they actually are minimal.)
    SmartDimmer/PRISM - On (off for a63 and lower)
    zRAM - off/none (default) (For lollipop it may help with multitasking at the price of speed, although you really shouldn't be trying to heavily multitasking with a 2012 N7 anyway) (Not very useful on android 4.x with >=1GB RAM, for lollipop it's not really helpful >=3Gb)
    Data remounting scripts - already included in ramdisk. Additional scripts not needed.

    I DO NOT RECOMMEND, nor will I support, any kind of optimization/superdupercharge/placebo script. All settings are already optimized in kernel and ramdisk. Using these scripts or tweaks will only lead to problems and performance degradation.


    If you'd like to buy me some caffeine so I can continue to fit studying and kernel-ing in my busy schedule, feel free to donate below. Thanks so much for all of your support! Clicking the thanks button is always appreciated too :)

    Alpha Changelog (stable feature list above):

    a77 - remove CM12.1 specific stuff from ramdisk

    a76 - Fix for 5.1

    a75 - 5.1 Lollipop update and patches

    Click to show complete changelog
    a74 -
    Fix for TricksterMod. Sync with cm12 ramdisk. Fake update dmcrypt to allow TRIM on encrypted devices (untested). Set ROW as default scheduler.a73 -
    Lollipop! Updated toolchain. Removed touch2wake due to the wakeup issues it created for some. Other stuff.a69 -
    Quick fix to allow overclocking on stock roms.

    a68 -
    Update to latest 4.4.3 kernel source
    Sync with latest CM 4.4.3 ramdisk
    Update to 4.8 toolchain
    F2FS support
    Zip installation supports all permutations of ext4/f2fs layouts
    Based on work by frantisek.nesveda, but modified to support all layouts and be more flexible
    Make sure to go to his thread -HERE- and click the thanks button!
    Upgrade to BFQ v7r4
    Adjust touchboost values
    Enable Kernel Samepage Merging - I've gone back and forth on this. For now, enabled.
    Probably some other changes I'm forgetting.

    a67 - Update + sync ramdisk from cm11 to enable native USB OTG. Add thermal charging shut off. Some kconfig tweaks.

    a66 - Only hold wakelock is touch/slide to wake is enabled. Tweak default BFQ values a bit.

    a65 - Update BFQ from 5.1 to 6r2. Set BFQ as default for testing. Tweak Deadline and CFQ (Franco's CFQ values). If CFQ is still causing reboots for some, I will revert it to stock in next build. Cgroups timer slack controller. Enable RCU priority boosting for testing.

    a64 - merge 4.4 kernel changes. Update ramdisk for 4.4

    a63.1 - CM hotfix

    a63 - Add Tegra 4 SmartDimmer (ported from TripNRaVeR's port for the One X). It either works much better or is completely broken. Either way, it's an improvement from the old SmartDimmer. Add necessary ramdisk change for PAC rom. Add dm9620 usb ethernet support. Switch back to linaro 4.7 toolchain from google 4.6 (used in mr2 for stability reasons).

    a62 - Add double tap to wake thanks to flar2 and sgt. meow. Add configurable timer to keep double tap to wake active after screen shut off. Remove Fsync toggle. Pointless and confusing with Dynamic Fsync available now. Update Dynamic Fsync from faux123. Set backlight levels back to defaults and disable otf_scaling. Some random stuffs.

    New sysfs:
    Value is in seconds. Defaults to 60. Set to 0 to keep double tap to wake permanently active at the price of battery.

    a61 - Enable compass driver. Add Dynamic Fsync by Faux123. Disable Fsync off at boot. Enable Dynamic Fsync at boot. Remove wifi pm fast/max toggle as it is now pointless and won't work since 4.3 kernel update. Add an older, but simpler, version of usb host mode by mehrvarz. Fixed and enabled many 4.3 config options relating to things like selinux.

    a60 - More ramdisk fixes

    a59 - Update cm10.2 ramdisk to fix storage issues. Fix 00su init.d.

    a58 - Incorporate cm10.2 ramdisk.

    a57 - Update to 4.3 kernel base. 4.3 stock only. Ramdisk base courtesy of Francisco Franco. Fsync off at boot since the internal storage is just so appallingly slow.

    a56 - Add back some missing config options removed in a55 to support various features. No CIFS support. Couldn't get it to boot for some reason.

    a55 - Add v2 of Tegra AHB patch set. Remove and revert USBHOST patches. Revert to almost stock kernel config for testing (will probably revert back later). Revert to stock PA ramdisk for testing. Tweak default TouchDemand parameters for bettter performance. Hard-code deadline and cfq tuneables thanks to the work by those in Franco's thread - details in commitlog on github. Set deadline as default I/O scheduler. Add core hotplugging lock during touch boost/input to interactive governor based on implementation in stock interactive governor (not fully tested). Other minor, inconsequential changes.

    a54 - Remove AHB bus drivers and patches.

    a53 - USBHOST support and patches. WiFi adhoc IBSS support.

    a52 - revert voltage table changes

    a51 - fix flickering at brightness level 13 when smartdimmer was enabled by setting SD min to 10. Re-enable a 3g modem reset assignment fix. It was disabled in a49/a50; let's see if re-enabling it causes 3g drops to return (Otherwise TCP proportional rate reduction was the cause). Re-enable wifi p2p patch that was disabled in a49 under the impression it wasn't included in the stock kernel when it actually is (whoops). Increase the some DVFS voltages so that that they are at least as high pre-a50 (according to DVFS debug showing actual running voltage) and not more than 25mV greater than pre-a50. Hard-code default pm_qos_max_cpus as 4 instead of ULONG_MAX. Fixes aesthetic bug where the default tegra hotplug max_cores was 2147483647 (For the curious - it is 2^31 − 1, the maximum value for a 32-bit signed integer in computing).

    Oh, and change thread title to accord with new XDA requirements.

    a50 - re-enable dynamic edp. Rework some edp limits. Rework DVFS voltage tables to better match frequencies, YMMV. Removed 1.7GHz max frequency option as it was pretty split whether your device could run it or not. If people were more responsible and wouldn't complain about issues when running 1.7 or higher I would leave it in, but unfortunately that's just not the case. So it saves me headaches in the future. Sorry. It's a minor increase from 1.6GHz and most can do 1.6 just fine.

    a49 - add some rwsem patches. Revert TCP proportional patch. Revert a wifi p2p patch. Fully stock /net and drivers/net in source now. Add custom min/max backlight interface. I'll add more info when I'm not so busy. Removed zRam support.

    Change your max backlight (min - 255) - /sys/module/board_grouper_panel/parameters/max_backlight
    Change your min backlight (1 - max) - /sys/module/board_grouper_panel/parameters/min_backlight
    Enable/Disable on-the-fly backlight level redistribution through available brightness slots based on new min/max using math below (0/1) - /sys/module/board_grouper_panel/parameters/otf_scaling
    - brightness = min_backlight + DIV_ROUND_CLOSEST(((max_backlight - min_backlight) * max((brightness - 10),0)),245);

    a48 - actually upload a kernel that is mr1 + row patches + flash fix

    a47 - mr1 + row patches + flash fix accidentally uploaded old kernel version...

    a46 - disable have_efficient_unaligned_access. Add USB Host mode charging patches.

    a45 - Fix adobe flash corruption. Add ARM unaligned access and enable have efficient unaligned access. Make sure slider min brightness and auto-brightness min have the same backlight value.

    a44 - Start over at mr1. Add ROW patches. Add LZ4 compression.

    a43 - revert all network and wireless patches since mr1.

    a42 - revert some config options. Fix fixed_mode on boot for multiboot. Sched_mc_power_savings set to 0 instead of 2 to see how it affects wakeup.

    a41 - ARM cpu topology and relevant patches. Enable multi-core scheduling. Enable maximum multi-core scheduling power savings for testing. Switch back to LZ4 ramdisk compression as Multiboot supports it now. Increase touchdemand sampling down factor since sampling rate was decreased previously.

    a40 - Revert SLQB. Add latest usb host mode charging from mehrvarz's repo. Force detect/report usb as ac, no apparent benefit. Enabled a config SVIPC or something... I forget. Enabled rndis support from CM.

    a39 - SLQB allocator. Switch back to Gzip ramdisk compression for multirom.

    a38 - Fix adobe flash playback. Super fast Lz4 compressed for ramdisk and kernel. Arm unaligned efficient memory access. Some misc. wifi and network patches. Many other changes. No guarantees.



    Alphas 5.1 -

    Click to show downloads for older versions of Android

    Alphas 5.1 -

    Alphas 5.0 -

    Alphas 4.4 -

    Milestone 4.3.x Releases -

    Alphas 4.3 (post mr2) -

    Alphas 4.3 (pre mr2) -

    Milestone 4.2.x Releases -

    Alphas 4.2.x -

    Legacy downloads available at http://goo.im/devs/Metallice/Nexus7

    Glossary of terms:

    (that one may not be as familiar with as things like CPU and GPU)

    Hotplugging - the process of turning CPU cores on and off.
    G core(s) - One of four ARM A9 CPU cores found in the Tegra 3 SoC
    LP (core) - The ARM A9 "Low-Power" CPU core found in the Tegra 3 SoC in addition to the 4 G cores. The LP core, contrary to what many seem to believe, does not run in tandem with the 4 G cores.
    Runnable Threads (hot plugging) - Limits turning on more cpu cores based on the average number of running threads
    Touchdemand - A modified ondemand-based governor that I designed and configured to better suit the Tegra 3 and android based on my observations
    Variant -
    Scheduler -
    Other things


    What's the difference between the mr(#) version/download and the a(#) version/download? Which should i download? What do these acronyms mean/stand for?

    The mr# (ex. mr1) stands for milestone release number #. The milestone builds are the stable, bug-free, and thoroughly, extensively, and expansively tested builds of m-kernel.

    The a# (ex. a38) stands for alpha build number #. The alpha builds listed under downloads are all of the alpha builds after the latest milestone build listed in reverse chronological and "morphological" (? FIX) order. It is the continuation of the "alpha branch" of m-kernel, and is basically the latest milestone with a ton of patches, fixes, and changes that are completely UNTESTED by anyone but me. The number and substantiality of changes since the latest milestone obviously vary and also depends on the number of alpha builds since the latest milestone release. An alpha build isn't guaranteed to be stable, working, and bug-free. They are testing builds leading up to the next milestone

    Do you recommend setting the maximum number of cores to 2?

    I don't necessarily recommend everyone do this, for it really comes down to personal preference. However, limiting the maximum cores to two is a very simple change to make that will slightly improve battery, with little to no impact on performance. Android 4.x is highly optimized for dual-core processing. There is no part of the Android 4.x OS that needs more than 2 cores for a smooth experience, and likewise there are few to no android applications that need 2 cores.

    For the most part, the 3rd and 4th g cores are only activated during time sensitive actions such as opening an app for the first time (i.e. not previously opened and cached in RAM) and during screen rotation. These are short lived operations meaning those 3rd and 4th g cores are quickly turned off afterwards. In essence a small hit to battery life for even smaller benefits.

    Why won't my minimum frequency go below 340MHz?!?

    As long as you don't use system tuner, the minimum frequency does go below 340MHz. The minimum frequency is temporarily raised to 340MHz during an audio event to prevent audio playback problems when using ondemand and similar governors. The minimum frequency returns to the previous value afterwards. Some apps may show the minimum frequency as 340MHz because clicking the app to open it created a sound causing the minimum to temporarily rise. The app does not change when the minimum frequency goes back to its previous value.

    Why can't over clock the GPU as high as I can on other kernels!?!

    You can. You have to raise the voltage for the top GPU slot. Other kernels do this automatically and to fixed values. The amount necessary depends on the GPU frequency you are trying to run and your device. No devices are alike and the voltage necessary at whatever frequency will vary considerably from device to devices. Be aware that having to overvolt to run a certain frequency may mean suggest that you shouldn't run that frequency anyway. Raising the GPU frequency and voltage has risks to consider

    What is this tegra 3 "variant" or whatever? How do I find it? What does it meeeeaaaannnn??!!?

    You can find this info in /sys/kernel/debug/t3_variant

    In the stock kernel/source, each device sku is recognized and assigned four ID values. For the CPU there is a primary "cpu speedo id" and a secondary "cpu process id". For the SOC, or core (think LP core, RAM, GPU, etc), there is a primary "soc speedo id" and a secondary "soc process id."

    Each "pair" of ids is used to choose the respective voltage tables for the components they represent. I'm going to ignore the soc/core ids as they aren't relevant to my point and are the same for all our devices.

    The CPU voltage tables are represented by ( cpu_speedo_id # , cpu_process_id #). The voltage tables that share the same first number, the cpu_speedo_id, all end with the same MHz value. To make things simple, Tegra uses the maximum frequency in the voltage table to determine the maximum frequency. All of our Nexus 7 Tegra 3s share the same cpu_speed_id, corresponding to a maximum frequency of 1.3GHz.

    The second number, the cpu_process_id, differs between all of our N7 T3's. Faux123 and everyone refers to value as our "variant." This value, cpu_process_id determines the voltages for each frequency in the table. For each increase in cpu_process_id, the RANGE of voltages for the voltage table is compressed by 25mV (i.e. the voltage for the top frequency is decreased by 25mV while the bottom stays at 800mV and the middle frequency voltages are adjusted accordingly).

    Therefore, in a direct sense, the cpu_process_id, or "variant", HAS NOTHING TO DO WITH CPU FREQUENCY. I'll repeat this. YOUR CPU_PROCESS_ID OR VARIANT HAS NO DIRECT CONNECTION TO THE MAXIMUM FREQUENCY CAPABILITIES OF YOUR CHIP. Variant/cpu_process_id refers to the voltage tolerance of your cpu. While there may be correlation or secondary connection to the maximum frequency capabilities of your chip, there is not direct connection. Additionally, cpu_process_id HAS NOTHING TO DO WITH YOUR SOC/CORE AT ALL, WHICH INCLUDES YOUR GPU/LP/RAM. A high cpu_process_id tells you nothing about your core and how high you can clock your GPU.

    TL;DR - Variant, or more accurately cpu_process_id, refers to voltage tolerance, and has no direct connection to the max frequency abilities of your chip, and definitely has absolutely no relationship to your core/GPU.

    To do:

    Core voltages quirks.

    Max freq delay necessity.

    Why doesn't the kernel come with recommended settings?
    Okay I know you guys must be antsy for some LP so here's an update.

    A pre a70 kernel is built. Nothing changed except for merging in the LP kernel/ramdisk changes. I'll be able to test later tonight. Once I can get it booting I can work on adding and testing other changes/updates before a70 is good to go.