Chuwi Hi9 Air

Chuwi Hi9 Air (Mediatek Helio X20 chipset)

Pretty complete hardware support and good stability with 8.1 Treble GSI (Oreo).

Steps to install

Baseline: Hi9 Air with Chuwi 20181122 stock ROM. Restore Chuwi stock ROM via the MTK SP Flash Windows toolkit using the Format All + Download option, in case anything goes wrong.

• enable "OEM unlock" in Android developer options

  ℹ️ type on build number seven times to unlock developer mode in Android system settings: System>About

• use factory settings reset in Android system settings
• wait for erase to finish and power off (long press)
• start device with power and vol+ simultaneously for bootloader menu, select "Fastboot Mode" via 'vol+', then confirm OK via 'vol-'
• unlock bootloader

  $ fastboot oem unlock
  

  Confirm OK on screen via 'vol+'.

  ⚠️ When relocking the bootloader again via fastboot oem lock the device won't boot custom images any longer...

• flash image with the fastboot utility (after uncompressing downloaded xz archive):

  $ fastboot erase system
  $ fastboot -u flash system system-arm64-aonly-gapps-su.img
  $ fastboot reboot
  

  🔁 This step may be repeated for later image releases with fixes and Android security patches...

  Alternatively, you could flash via TWRP as "System Image". Refrain from formatting data, as the device will fail to boot then 👎): Link

• wait patiently for another erase job to finish and initial boot (displays android animation instead of CHUWI) to complete: This will take several minutes

Hardware support

Component	Comment
Camera	yes (both work, front cam orientation upside down)
Speaker / Mic	yes / yes
Bluetooth	yes
WiFi	yes (but signal seems worse compared to stock ROM)
SIM / Mobile Data	partial (SIM1 only, may not reactivate from standby occasionally)
Voice	yes
SMS	yes
VoLTE	no (MTK 6797)
Fingerprint	n/a
NFC	n/a
SD Card	yes
Casting	no, only via Google Home (as for Chuwi stock ROM)

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Tested by bofh2k - phh-treble 8.1 v31 (arm64-aonly-gapps-su) - 2019-05-31