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Building kernel

Before building kernel grab gcc-linaro-6.3.1-2017.05-x86_64_arm-eabi.tar.xz from here

or if you want 64-bit kernel then gcc-linaro-6.3.1-2017.05-x86_64_aarch64-elf.tar.xz from here

Then run

# 32-bit
mkdir ../build-aarch32
make O=$(readlink -f ../build-aarch32) -j$(nproc) \
  ARCH=arm CROSS_COMPILE=<full path toolchain directory>/bin/arm-eabi- \
  LGE_TARGET_PLATFORM=mt6750 LGE_TARGET_DEVICE=lv5 MTK_DTBO_FEATURE=yes \
  lv5_global_com_defconfig
make O=$(readlink -f ../build-aarch32) -j$(nproc) \
  ARCH=arm CROSS_COMPILE=<full path toolchain directory>/bin/arm-eabi- \
  LGE_TARGET_PLATFORM=mt6750 LGE_TARGET_DEVICE=lv5 MTK_DTBO_FEATURE=yes \
  all
# 64-bit
mkdir ../build-aarch64
make O=$(readlink -f ../build-aarch64) -j$(nproc) \
  ARCH=arm64 CROSS_COMPILE=<full path toolchain directory>/bin/aarch64-elf- \
  LGE_TARGET_PLATFORM=mt6750 LGE_TARGET_DEVICE=lv5 MTK_DTBO_FEATURE=yes \
  lv5_global_com_defconfig
make O=$(readlink -f ../build-aarch64) -j$(nproc) \
  ARCH=arm64 CROSS_COMPILE=<full path toolchain directory>/bin/aarch64-elf- \
  LGE_TARGET_PLATFORM=mt6750 LGE_TARGET_DEVICE=lv5 MTK_DTBO_FEATURE=yes \
  all

Booting kernel

Use following configuration when building BOOT.IMG

For 64-bit:

bootsize = 0x1300000
pagesize = 0x800
kerneladdr = 0x40100000
ramdiskaddr = 0x4A000000
secondaddr = 0x40f00000
tagsaddr = 0x44000000
name =
cmdline = bootopt=64S3,32N2,64N2 androidboot.hardware=mlv5 buildvariant=user androidboot.selinux=permissive

For 32-bit:

bootsize = 0x1300000
pagesize = 0x800
kerneladdr = 0x40008000
ramdiskaddr = 0x45000000
secondaddr = 0x40f00000
tagsaddr = 0x44000000
name =
cmdline = bootopt=64S3,32N2,32N2 androidboot.hardware=mlv5 buildvariant=user

To actually boot kernel you need to inject exploit into BOOT.IMG

See instructions here

Debugging kernel

You can enable UART over USB by flashing LK payload built with ENABLE_UART set.

KDB/KGDB

If you want to use KDB/KGDB you may have to disable watchdog driver, otherwise your device will reboot if kept paused for too long.

What works

  • Stock Oreo ROM works fine on both 32-bit and 64-bit kernel
  • Audio playback/recording
  • Wi-Fi, mobile network, calls, SMS
  • Camera

What does not work

  • LG crash handler support is not implemented yet on 64-bit kernel, device will enter LK's crash handler after reboot.

What was not tested

  • Bluetooth
  • GPS

Virtualization support

64-bit kernel supports KVM.

If you want to use KVM then build kernel from kvm branch as master currently is broken.

Before starting VM disable HPS and CPU deep sleep, otherwise you will experience kernel crash when entering sleep mode.

echo 0 > /proc/hps/enabled
for cpu in {0..7}; do
  echo 1 > "/sys/devices/system/cpu/cpu${cpu}/cpuidle/state0/disable"
  echo 1 > "/sys/devices/system/cpu/cpu${cpu}/online"
done

After you done with VM re-enable HPS and deep sleep to avoid draining your battery.

echo 1 > /proc/hps/enabled
for cpu in {0..7}; do
  echo 0 > "/sys/devices/system/cpu/cpu${cpu}/cpuidle/state0/disable"
done