Building a kernel for the Razor Phone 2 - Live feed

I am going to build a kernel for the Razor Phone 2 from scratch and log all my steps in this post for everyone that's interested in building their own kernel. I encourage everyone to follow along, try these steps and raise questions or propose better ways of doing things as we go along.

I am going to list the prerequisites in post #2, a raw log with all mistakes, dead ends and troubleshooting in post #3, and a sanitised version of the working steps in post #4.

Everything after that is open discussion. Let the games begin :-)

Prerequisites:

Identify device model:
----------------------
- getprop ro.product.device = aura
- getprop ro.product.model = Phone 2
- getprop ro.product.name = cheryl2 (chery12)
- OS =
- OS version =
- Architecture =


Confirm prerequisites:
----------------------
- Magisk root is installed
- TWRP is installed
- Kernel source is available for that particular model: Yes, we are going to use https://github.com/arter97/android_kernel_razer_sdm845
- If an alternative kernel is already available as update.zip, install it as a test (and to have a fallback)

Raw log:
--------------

Prepare build environment (Kali VM):
--------------------------------------------------
- Install Virtualbox
- Download Kali VM from https://www.offensive-security.com/k...mage-download/
- Import Kali VM into VirtualBox
- Start VBox, log on as root/toor, change password and prep OS:

Code:

---

apt update && apt full-upgrade
adduser nethunter
usermod -a -G sudo nethunter

---

- reboot & login as nethunter


Next:

- Install (google) toolchains and dependencies:

Code:

---

cd ~
mkdir toolchain toolchain64
git clone https://android.googlesource.com/platform/prebuilts/gcc/linux-x86/aarch64/aarch64-linux-android-4.9 -b  pie-release toolchain64
export ARCH=arm64
export SUBARCH=arm64
export CROSS_COMPILE=`pwd`/toolchain64/bin/aarch64-linux-android-

---

Prepare kernel:
------------------
- Clone kernel source:

Code:

---

git clone https://github.com/arter97/android_kernel_razer_sdm845

---

- install bc

Code:

---

apt install bc

---

- Build test kernel without any mods:

Code:

---

cd android_kernel_razer_sdm845

cp defconfig .config ## This seems to be the original authors config
make menuconfig
cp .config arch/arm64/configs/nethunter_defconfig
make

---

Results in this error

Code:

---

arch/arm64/Makefile:74: *** /home/arter97/arm32-gcc/bin/arm-eabi-gcc not found, check CROSS_COMPILE_ARM32.  Stop.

---

There seem to be some paths hardcoded somewhere. Probably in the Makefile but let's do a search:

Code:

---

grep -r "arter97" *

---

And there it is:

Code:

---

<snip>
Makefile:override CROSS_COMPILE        := /home/arter97/arm64-gcc/bin/aarch64-elf-
Makefile:override CROSS_COMPILE_ARM32        := /home/arter97/arm32-gcc/bin/arm-eabi-
<snip>

---

Let's edit the Makefile and remove the offending lines:

Code:

---

vi Makefile
# searching for "override" takes us to the following three lines, let's comment them out like this:

override ARCH          := arm64
override CROSS_COMPILE  := /home/arter97/arm64-gcc/bin/aarch64-elf-
override CROSS_COMPILE_ARM32    := /home/arter97/arm32-gcc/bin/arm-eabi-

---

Running make again causes this error:

Code:

---

arch/arm64/Makefile:74: *** /home/nethunter/toolchain/bin/arm-eabi-gcc not found, check CROSS_COMPILE_ARM32.  Stop.

---

Let's get a 32bit toolchain too then:

Code:

---

cd ~
git clone https://android.googlesource.com/platform/prebuilts/gcc/linux-x86/arm/arm-eabi-4.7 toolchain
export CROSS_COMPILE_ARM32=~/toolchain/bin/arm-eabi-

---

Let's compile again:

Code:

---

cd ~/android_kernel_razer_sdm845
make

---

Results in another error:

Code:

---

make: *** [Makefile:1189: prepare-compiler-check] Error 1

---

Looks like we need other toolchains. Let's try linaro:

Code:

---

cd ~
rm -rf toolchain toolchain64
mkdir toolchain toolchain64
wget https://releases.linaro.org/components/toolchain/binaries/7.4-2019.02/arm-eabi/gcc-linaro-7.4.1-2019.02-x86_64_arm-eabi.tar.xz
wget https://releases.linaro.org/components/toolchain/binaries/7.4-2019.02/aarch64-elf/gcc-linaro-7.4.1-2019.02-x86_64_aarch64-elf.tar.xz
tar xJf gcc-linaro-7.4.1-2019.02-x86_64_arm-eabi.tar.xz -C toolchain --strip-components=1
tar xJf gcc-linaro-7.4.1-2019.02-x86_64_aarch64-elf.tar.xz -C toolchain64 --strip-components=1

---

Same error. Looking around I found pre-compiled toolchains in the github account of the original author of this kernel. Let's use these:

Code:

---

cd ~
rm -rf toolchain toolchain64
mkdir toolchain toolchain64

git clone https://github.com/arter97/arm32-gcc toolchain
git clone https://github.com/arter97/arm64-gcc toolchain64
export ARCH=arm64
export SUBARCH=arm64
export CROSS_COMPILE=~/toolchain64/bin/aarch64-elf-
export CROSS_COMPILE_ARM32=~/toolchain/bin/arm-eabi-

---

And let's try again:

Code:

---

cd ~/android_kernel_razer_sdm845
make

---

Bingo. We have a kernel.


Let's wait for everyone to catch up and aim for step two: packaging up and installing the test kernel tomorrow, ok?

Pretty log:
----------------

Prepare build environment (Kali VM):
--------------------------------------------------
- Install Virtualbox
- Download Kali VM from https://www.offensive-security.com/k...mage-download/
- Import Kali VM into VirtualBox
- Start VBox, log on as root/toor, change password and prep OS:

Code:

---

apt update && apt full-upgrade
adduser nethunter
usermod -a -G sudo nethunter

---

- reboot & login as nethunter


Next:

- Install toolchains and dependencies:

Code:

---

cd ~
mkdir toolchain toolchain64
git clone https://github.com/arter97/arm32-gcc toolchain
git clone https://github.com/arter97/arm64-gcc toolchain64
sudo apt install bc
export ARCH=arm64
export SUBARCH=arm64
export CROSS_COMPILE=~/toolchain64/bin/aarch64-elf-
export CROSS_COMPILE_ARM32=~/toolchain/bin/arm-eabi-

---

- Download, configure, and build vanilla kernel:

Code:

---

cd ~
git clone https://github.com/arter97/android_kernel_razer_sdm845
cd android_kernel_razer_sdm845
cp defconfig .config
vi Makefile
# Delete three lines starting with "override"
make menuconfig
cp .config arch/arm64/configs/nethunter_defconfig
make

---

@nikmel420:

Could you run these commands for me and post the output please?

getprop ro.product.device
getprop ro.product.model
getprop ro.product.name

Many thanks

Sorry sorry, ok different timezone but saint bernard puppy wore me out went to bed early. I'll make sure all notifications are on so I dont miss you again.

Ok um let me do 6am feed walk dog feed me drink coffee and the start. Thank you.

I'm not sure that's a good idea. My day seems to be your night and there will be a lot of alarms getting you out of bed ;-)
That's ok though because I can spend my day experimenting and posting my result and you can have a go at it when I'm in bed.

If you could get me those details and install Kali, that will set us up for tomorrow.
The toolchain and kernel config will take a day because I've already had a little peek and there are a few minor courve b.a.l.l.s. (first time censored - yeah) along the way.

Give me time F it Zulu/Greenwich, or east us

I'll have all this and be ready then

Kali always installed not get reinstall after every chapter in the book. Thsts a long book

Can we secedual for this weekend works kicking my *** . I dont want to make I committment I cant keep.

No problems at all.


I have picked a kernel and toolchain and will document the process of how I arrived at those decisions.
If you could run those commands, root your phone and install TWRP then we can hit the ground running on the weekend.

I also encourage everyone else that is interested in porting NetHunter to new phones to follow along. Doesn't matter if you have a Razor phone or not, it is still a useful and fun exercise that you can apply to your own device.

Ok sorry I'm late to the game between work and family I have a lot going on. Let me know if there's anything you need me to test etc. Right now Im rooted running magisk w/the AT&T firmware. Had a hard time getting TWRP to ever work with the bootloader, but maybe there was something I was missing. I can't thank you enough for taking on this challenge. I know this is sold as a "gaming" phone. Truth be told I don't really even do mobile gaming. I liked the specs and I think it will make a great penetration device.

How did you get twrp? I'm got magick and magick manager. But I cant even get twrp even from twrp app. Is that the one u using. I been stuck awhile

I dont game on my phone. But tmobile new upgrade program this was less then a downpayment and so I went with this one. But been years using adb not Odin.

Welcome aboard @Rabid_Root

@nikmel420 - It seems that the only option to get TWRP for the Razer 2 is to install it together with the Arter97 kernel:
https://forum.xda-developers.com/raz...one-2-t3914996

That's ok though because this is the kernel I picked as basis for NetHunter anyway.

Are you installing the zip like it says I keep getting error N

Found it run:
adb shell get ro.boot.slot_suffif
Get _a or _b
Fastboot flash boot_a/b arter97*

Since u already made one how about I test it for ya. You can show me how when your not busy

I don't have anything yet except an idea of which kernel source to use. That might change down the track but I am going to start with this one:

https://github.com/arter97/android_kernel_razer_sdm845

The reason that I picked that on is because it has the most activity in the xda forum:
https://forum.xda-developers.com/raz...one-2-t3914996

And no major issues reported.

First things first through, I need someone to confirm that TWRP works, system & data can be mounted in TWRP and I need the output of the following commands:

https://forum.xda-developers.com/raz...one-2-t3914996

getprop ro.product.device
getprop ro.product.model
getprop ro.product.name

Please don't run these commands in TWRP but when you are booted into the normal system please.

Ok I'm on it. The arter97. I haven't tested. But says it has a couple realtek drivers already. Let me do those things you asked

Quote:

---

Originally Posted by re4son

I don't have anything yet except an idea of which kernel source to use. That might change down the track but I am going to start with this one:

https://github.com/arter97/android_kernel_razer_sdm845

The reason that I picked that on is because it has the most activity in the xda forum:
https://forum.xda-developers.com/raz...one-2-t3914996

And no major issues reported.

First things first through, I need someone to confirm that TWRP works, system & data can be mounted in TWRP and I need the output of the following commands:

https://forum.xda-developers.com/raz...one-2-t3914996

getprop ro.product.device
getprop ro.product.model
getprop ro.product.name

Please don't run these commands in TWRP but when you are booted into the normal system please.

---

ok it deleted twrp i got a few ideas . but getprop is giving unknown command. im on kali but installed not virtual. might need more clarification were to run those

Boot your phone normally and install connectbot
Open a localhost session and type in those commands

twrp wont mount storage. conectbot wont connect. i cant help. maybe some rest

ok already said i was an idiot. i dont recall putting my pin in twrp to mount it. buti forget alot moving forward again

ok already said i was an idiot. i don't recall putting my pin in twrp to mount it. but i forget alot moving forward again. reflashed original FW

fastboot boot_a arter97-kernel-r10-20190804.img
fastboot boot_b arter97-kernel-r10-20190804.img

fastboot reboot

im not sure why or why there's a b. but running the _a _b at same time keeps twpr over hard resets. im switching pc's i don't know why i cant get a shell. but cant hurt

i asked before just want to be sure. do i need to use a VM? i dont see why would matter but i dont see much

getprop ro.product.device
aura
getprop ro.product.model
Phone 2
getprop ro.product.name
cheryl2 (chery12)Attachment 3544

Perfect, thanks.
Can you mount data and system in TWRP?

after i entered pin code yes, was also able to mount usb storage. but i tried a nethunter generic install and the magisk module install. both say succeed but not installed when boots. im pretty sure all safeties off

under modifying kernel what do i replace msm8974_sec_defconfig with?

im going to guess deconfig (i missed it)

Let's install suitable toolchains. I'm continuing with my log in post #3

First we need both a 32bit and a 64bit toolchain
Next the google one is not suitable and the linaro one isn't either
I ended up using one build very recently by the author of the original kernel we are using

We also have to edit the Makefile to get rid of some hardcoded paths

Attachment 3547


shoot sorry i was adjusting my time. hers were im at i stopped since no real errors. except the golum things you need first could t find it. is it wearing the ring

im here a ran the first 3 comands. was gonna do the pach line when came and saw about make file
i missed the post on tolchains and the cusom makefileAttachment 3548

I'd stick to following these steps:

https://forums.kali.org/showthread.p...7030#post87030


That'll get you a test kernel. Next we are going to package it up and install it.
There's no point working with a kernel that doesn't work out of the box.

There are a lot of changes in the Android build of the Razer 2 and we have to go slowly and systematically.

will do slow is cool with me. i rushed on the last one the gemini. i like the keybord but the gpd pocket better anyway. andthis one just feals solid idea why i cant get any nethunter flashed even the magisk one they say succeed but are gone or never ther after reboot,the 5 inch one was cool but i cant find it in this mes

root and twrp wont stick ive been on xda looking for the step i missed.looks like they still figuring the fix. its passed my pay grade

The final rooting solution determines the location of the nethunter kernel so we can't really do anything until that's sorted.
How about we check-in to this thread every Friday to confirm the status? Would you mind posting a link to the relevant xda discussion @nikmel420 so we can stay up to date?

Many thanks