Ubuntu Touch porting notes for the Redmi Note 7 Pro
In case you have a sense of deja-vu when reading this post, it's because indeed this is not the first time I try porting a device to Ubuntu Touch. The previous attempt, however, was with another phone model (and manufacturer), and did not have a happy ending. This time it went better, although the real ending is still far away; but at least I have something to celebrate.
The phone
I made myself a Christmas present and bought a Xiaomi Redmi Note 7 Pro, a dual-SIM phone from 2019 with 6GB of RAM and 128GB of flash storage. To be totally honest, I bought it by mistake: the phone I really wanted to buy is the Redmi Note 7 (without the "Pro"), because it's a modern phone that is working reasonable well with Ubuntu Touch. The online shop where I bought it from let me choose some options, including the RAM size, so I chose the maximum available (6GB) without being aware that this would mean that I would be buying the "Pro" device — the shop did not alter the item name, so I couldn't really know. Unfortunately, the two versions are two rather different beasts, powered by different SoC; both are produced by Qualcomm, so they are not that different, but it's enough to make the installation of Ubuntu Touch impossible.
But between the choice of retuning the phone to the shop and begin a new porting adventure, I stood firm and went for the latter. Hopefully I won't regret it (if everything goes bad, I can still use it with LineageOS, which runs perfectly on it).
Moreover, there already exist a port of Ubuntu Touch for this phone, which actually works reasonably well (I tried it briefly, and many things were working), but the author claims to be a novice and indeed did not follow the best git practices when working on the source code, so it's hard to understand what was changed and why. But if you are looking for a quick way to get Ubuntu Touch working on this phone, you are welcome to have a look at this Telegram channel.
What follows are the raw notes of my attempts. They are here so that search engines can index the error messages and the various logs, and hopefully help someone hitting similar errors on other devices to find his way out.
Getting Halium and the device source code
Installed the dependencies like in the first step. repo was not found in the
Ubuntu 20.04 archives, but I had it installed anyway due to my work on a Yocto
device.
Since my device has Android 9 on it, I went for Halium 9:
repo init -u git://github.com/Halium/android.git -b halium-9.0 --depth=1 repo sync -c -j 16
The official LineageOS repository for the Xiaomi Redmi Note 7 Pro is android_device_xiaomi_violet, but the page with the official build has been taken down (some DMCA violation, if you believe the forums) and no development has been happening since last year. A more active forum thread uses another repository which seems to be receiving more frequent updates, so I chose to base my port on that.
I actually tested that LineageOS image on my phone, and verified that all the hardware was working properly.
Initially, I created forks of the relevant repository under my own gitlab account, but then I though (especially looking at the Note 7 port) that creating a group just for this port would make people's life easier, because they wouldn't need to navigate through my 1000 personal projects to find what is relevant for this port. So, I created these forks:
- gitlab.com/ubuntu-touch-xiaomi-violet/android_device_xiaomi_violet
- gitlab.com/ubuntu-touch-xiaomi-violet/android_kernel_xiaomi_violet
- gitlab.com/ubuntu-touch-xiaomi-violet/android_vendor_xiaomi_violet
Next, created the halium/devices/manifests/xiaomi_violet.xml file with this content:
<?xml version="1.0" encoding="UTF-8"?> <manifest> <!-- Remotes --> <remote name="ubuntu-touch-xiaomi-violet" fetch="https://gitlab.com/ubuntu-touch-xiaomi-violet" revision="halium-9.0"/> <!-- Device Tree --> <project path="device/xiaomi/violet" name="android_device_xiaomi_violet" remote="ubuntu-touch-xiaomi-violet" /> <!-- Kernel --> <project path="kernel/xiaomi/violet" name="android_kernel_xiaomi_violet" remote="ubuntu-touch-xiaomi-violet" /> <!-- Proprietary/Vendor blobs --> <project path="vendor/xiaomi/violet" name="android_vendor_xiaomi_violet" remote="ubuntu-touch-xiaomi-violet" /> </manifest>
Fetching all the sources mentioned in the manifest:
./halium/devices/setup violet
Full output:
***************************************** I: Configuring for device xiaomi_violet ***************************************** Fetching projects: 100% (393/393), done. hardware/qcom/audio-caf/apq8084: Shared project LineageOS/android_hardware_qcom_audio found, disabling pruning. hardware/qcom/audio-caf/msm8916: Shared project LineageOS/android_hardware_qcom_audio found, disabling pruning. hardware/qcom/audio-caf/msm8952: Shared project LineageOS/android_hardware_qcom_audio found, disabling pruning. hardware/qcom/audio-caf/msm8960: Shared project LineageOS/android_hardware_qcom_audio found, disabling pruning. hardware/qcom/audio-caf/msm8974: Shared project LineageOS/android_hardware_qcom_audio found, disabling pruning. hardware/qcom/audio-caf/msm8994: Shared project LineageOS/android_hardware_qcom_audio found, disabling pruning. hardware/qcom/audio-caf/msm8996: Shared project LineageOS/android_hardware_qcom_audio found, disabling pruning. hardware/qcom/audio-caf/msm8998: Shared project LineageOS/android_hardware_qcom_audio found, disabling pruning. hardware/qcom/audio-caf/sdm845: Shared project LineageOS/android_hardware_qcom_audio found, disabling pruning. hardware/qcom/audio-caf/sm8150: Shared project LineageOS/android_hardware_qcom_audio found, disabling pruning. hardware/qcom/audio/default: Shared project LineageOS/android_hardware_qcom_audio found, disabling pruning. hardware/qcom/display: Shared project LineageOS/android_hardware_qcom_display found, disabling pruning. hardware/qcom/display-caf/apq8084: Shared project LineageOS/android_hardware_qcom_display found, disabling pruning. hardware/qcom/display-caf/msm8916: Shared project LineageOS/android_hardware_qcom_display found, disabling pruning. hardware/qcom/display-caf/msm8952: Shared project LineageOS/android_hardware_qcom_display found, disabling pruning. hardware/qcom/display-caf/msm8960: Shared project LineageOS/android_hardware_qcom_display found, disabling pruning. hardware/qcom/display-caf/msm8974: Shared project LineageOS/android_hardware_qcom_display found, disabling pruning. hardware/qcom/display-caf/msm8994: Shared project LineageOS/android_hardware_qcom_display found, disabling pruning. hardware/qcom/display-caf/msm8996: Shared project LineageOS/android_hardware_qcom_display found, disabling pruning. hardware/qcom/display-caf/msm8998: Shared project LineageOS/android_hardware_qcom_display found, disabling pruning. hardware/qcom/display-caf/sdm845: Shared project LineageOS/android_hardware_qcom_display found, disabling pruning. hardware/qcom/display-caf/sm8150: Shared project LineageOS/android_hardware_qcom_display found, disabling pruning. hardware/qcom/media: Shared project LineageOS/android_hardware_qcom_media found, disabling pruning. hardware/qcom/media-caf/apq8084: Shared project LineageOS/android_hardware_qcom_media found, disabling pruning. hardware/qcom/media-caf/msm8916: Shared project LineageOS/android_hardware_qcom_media found, disabling pruning. hardware/qcom/media-caf/msm8952: Shared project LineageOS/android_hardware_qcom_media found, disabling pruning. hardware/qcom/media-caf/msm8960: Shared project LineageOS/android_hardware_qcom_media found, disabling pruning. hardware/qcom/media-caf/msm8974: Shared project LineageOS/android_hardware_qcom_media found, disabling pruning. hardware/qcom/media-caf/msm8994: Shared project LineageOS/android_hardware_qcom_media found, disabling pruning. hardware/qcom/media-caf/msm8996: Shared project LineageOS/android_hardware_qcom_media found, disabling pruning. hardware/qcom/media-caf/msm8998: Shared project LineageOS/android_hardware_qcom_media found, disabling pruning. hardware/qcom/media-caf/sdm845: Shared project LineageOS/android_hardware_qcom_media found, disabling pruning. hardware/qcom/media-caf/sm8150: Shared project LineageOS/android_hardware_qcom_media found, disabling pruning. hardware/ril: Shared project LineageOS/android_hardware_ril found, disabling pruning. hardware/ril-caf: Shared project LineageOS/android_hardware_ril found, disabling pruning. hardware/qcom/wlan: Shared project LineageOS/android_hardware_qcom_wlan found, disabling pruning. hardware/qcom/wlan-caf: Shared project LineageOS/android_hardware_qcom_wlan found, disabling pruning. hardware/qcom/bt: Shared project LineageOS/android_hardware_qcom_bt found, disabling pruning. hardware/qcom/bt-caf: Shared project LineageOS/android_hardware_qcom_bt found, disabling pruning. Updating files: 100% (67031/67031), done.nel/testsUpdating files: 36% (24663/67031) lineage/scripts/: discarding 1 commits Updating files: 100% (1406/1406), done.ineageOS/android_vendor_qcom_opensource_thermal-engineUpdating files: 47% (666/1406) Checking out projects: 100% (392/392), done. ******************************************* I: Refreshing device vendor repository: device/xiaomi/violet I: Processing proprietary blob file: device/xiaomi/violet/./proprietary-files.txt I: Processing fstab file: device/xiaomi/violet/./rootdir/etc/fstab.qcom I: Removing components relying on SettingsLib from: device/xiaomi/violet *******************************************
Starting the build
Setting up the environment:
$ source build/envsetup.sh including device/xiaomi/violet/vendorsetup.sh including vendor/lineage/vendorsetup.sh $
Running the breakfast command:
$ breakfast violet including vendor/lineage/vendorsetup.sh Trying dependencies-only mode on a non-existing device tree? ============================================ PLATFORM_VERSION_CODENAME=REL PLATFORM_VERSION=9 LINEAGE_VERSION=16.0-20210109-UNOFFICIAL-violet TARGET_PRODUCT=lineage_violet TARGET_BUILD_VARIANT=userdebug TARGET_BUILD_TYPE=release TARGET_ARCH=arm64 TARGET_ARCH_VARIANT=armv8-a TARGET_CPU_VARIANT=kryo300 TARGET_2ND_ARCH=arm TARGET_2ND_ARCH_VARIANT=armv8-a TARGET_2ND_CPU_VARIANT=cortex-a75 HOST_ARCH=x86_64 HOST_2ND_ARCH=x86 HOST_OS=linux HOST_OS_EXTRA=Linux-5.4.0-58-generic-x86_64-Ubuntu-20.04.1-LTS HOST_CROSS_OS=windows HOST_CROSS_ARCH=x86 HOST_CROSS_2ND_ARCH=x86_64 HOST_BUILD_TYPE=release BUILD_ID=PQ3A.190801.002 OUT_DIR=/home/mardy/projects/port/halium/out PRODUCT_SOONG_NAMESPACES= hardware/qcom/audio-caf/sm8150 hardware/qcom/display-caf/sm8150 hardware/qcom/media-caf/sm8150 ============================================
Building the kernel
The configuration needs to be adapted for Halium. Locating the kernel config:
$ grep "TARGET_KERNEL_CONFIG" device/xiaomi/violet/BoardConfig.mk TARGET_KERNEL_CONFIG := vendor/violet-perf_defconfig $
Getting the Mer checker tool and running it:
git clone https://github.com/mer-hybris/mer-kernel-check cd mer-kernel-check ./mer_verify_kernel_config ../kernel/xiaomi/violet/arch/arm64/configs/vendor/violet-perf_defconfig
Prints lots of warnings, starting with:
WARNING: kernel version missing, some reports maybe misleading
To help the tool, we need to let him know the kernel version. It can be seen at
the beginning of the kernel Makefile, located in
../kernel/xiaomi/violet/Makefile; in my case it was
VERSION = 4 PATCHLEVEL = 14 SUBLEVEL = 83 EXTRAVERSION =
So I edited the configuration file
../kernel/xiaomi/violet/arch/arm64/configs/vendor/violet-perf_defconfig and
added this line at the beginning:
# Version 4.14.83
then ran the checker tool again. This time the output was a long list of kernel
options that needed to be fixed, but as I went asking for some explanation in
the Telegram channel for Ubuntu Touch porters, I was told that I could/should
skip this test and instead use the check-kernel-config tool from
Halium.
I downloaded it, made it executable (chmod +x check-kernel-config) and ran
it:
./check-kernel-config kernel/xiaomi/violet/arch/arm64/configs/vendor/violet-perf_defconfig [...lots of red and green lines...] Config file checked, found 288 errors that I did not fix.
I ran it again with the -w option, and it reportedly fixed 287 errors. Weird,
does that mean that an error was still left? I ran the tool again (without
-w), and it reported 2 errors. Ran it once more in write mode, and if fixed
them. So, one might need to run it twice.
Next, added the line
BOARD_KERNEL_CMDLINE += console=tty0
in device/xiaomi/violet/BoardConfig.mk. One more thing that needs to be done
before starting the build is fixing the mount
points,
so I opened device/xiaomi/violet/rootdir/etc/fstab.qcom and changed the type
of the userdata partition from f2fs to ext4. There were no lines with the
context option, so that was the only change I needed to do.
At this point, while browsing throught the documentation, I found a link to this page which contains some notes on Halium 9 porting, which are substantially different from the official porting guide in halium.org (which I was already told in Telegram to be obsolete in several points).
So, following the instructions from this new link I ran
hybris-patches/apply-patches.sh --mb
which completed successfully.
Then, continuing following the points from this page, I edited device/xiaomi/violet/lineage_violet.mk, commented out the lines
$(call inherit-product, $(SRC_TARGET_DIR)/product/full_base_telephony.mk) # ... $(call inherit-product, vendor/lineage/config/common_full_phone.mk)
and replaced the first one with a similar line pointing to halium.mk. For the
record, a find revealed that the SRC_TARGET_DIR variable in my case was
build/make/target/. It contained also the halium.mk file, which was created
by the hybris patches before. As for removing the Java dependencies, I cound't
find any modules similar to those listed in this
commit
in any of the makefiles in my source tree, so I just started the build:
source build/envsetup.sh && breakfast violet make halium-boot
This failed the first time with the compiler being killed (out of memory, most likely), but it succeeded on the second run. There was a suspicious warning, though:
drivers/input/touchscreen/Kconfig:1290:warning: multi-line strings not supported
And indeed my kernel/xiaomi/violet/drivers/input/touchscreen/Kconfig had this line:
source "drivers/input/touchscreen/ft8719_touch_f7b/Kconfig
(notice the unterminated string quote). I don't know if this had any impact on the build, but just to be on the safe side I added the missing quote and rebuilt.
Building the system image
Running
make systemimage
failed pretty soon:
ninja: error: '/home/mardy/projects/port/halium/out/soong/host/linux-x86/framework/turbine.jar', needed by '/home/mardy/projects/port/halium/out/soong/.intermediates/libcore/core-oj/android_common/turbine/core-oj.jar', missing and no known rule to make it
The error is due to all the Java-related stuff that I should have disabled but
couldn't find. So, I tried to have a look at the changes made on another
xiaomi
device
(lavender, the Redmi note 7, which might not be that different, I thought)
and started editing device/xiaomi/violet/device.mk and removing a couple of
Android packages. Eventually the build proceeded, just to stop at a python
error:
File "build/make/tools/check_radio_versions.py", line 56
print "*** Error opening \"%s.sha1\"; can't verify %s" % (fn, key)
^
SyntaxError: invalid syntax
Yes, it's the python3 vs python2 issue, since in my system python is python
version 3. In order to fix it, I created a virtual environment:
virtualenv --python 2.7 ../python27 # adjust the path to your prefs source ../python27/bin/activate
Remember that the second line must be run every time you'll need to setup the
Halium build environment (that is, every time you run breakfast).
The build then proceeded for several minutes, until it failed due to some unresolved symbols:
prebuilts/gcc/linux-x86/aarch64/aarch64-linux-android-4.9/aarch64-linux-android/bin/ld.gold: error: /home/mardy/projects/port/halium/out/target/product/violet/obj/STATIC_LIBRARIES/lib_driver_cmd_qcwcn_intermediates/lib_driver_cmd_qcwcn.a: member at 7694 is not an ELF object external/wpa_supplicant_8/hostapd/src/drivers/driver_nl80211.c:7936: error: undefined reference to 'wpa_driver_set_p2p_ps' /home/mardy/projects/port/halium/out/target/product/violet/obj/EXECUTABLES/hostapd_intermediates/src/drivers/driver_nl80211.o:driver_nl80211.c:wpa_driver_nl80211_ops: error: undefined reference to 'wpa_driver_set_ap_wps_p2p_ie' /home/mardy/projects/port/halium/out/target/product/violet/obj/EXECUTABLES/hostapd_intermediates/src/drivers/driver_nl80211.o:driver_nl80211.c:wpa_driver_nl80211_ops: error: undefined reference to 'wpa_driver_get_p2p_noa' /home/mardy/projects/port/halium/out/target/product/violet/obj/EXECUTABLES/hostapd_intermediates/src/drivers/driver_nl80211.o:driver_nl80211.c:wpa_driver_nl80211_ops: error: undefined reference to 'wpa_driver_set_p2p_noa' /home/mardy/projects/port/halium/out/target/product/violet/obj/EXECUTABLES/hostapd_intermediates/src/drivers/driver_nl80211.o:driver_nl80211.c:wpa_driver_nl80211_ops: error: undefined reference to 'wpa_driver_nl80211_driver_cmd'
As people told me in the Telegram channel, this driver is not used since "our
wpa_supplicant talks to kernel directly". OK, so I simply disabled the
driver, copying again from the lavender Halium
changes:
commented out the BOARD_WLAN_DEVICE := qcwcn line (and all lines referring
this variable) from device/xiaomi/violet/BoardConfig.mk and ran make
systemimage again. This time, surprisingly, it all worked.
Try it out
I first tried to flash the kernel only. I rebooted into fastboot, and on my PC ran this:
cout fastboot flash boot halium-boot.img
I then rebooted my phone, but after showing the boot logo for a few seconds it would jump to the fastboot screen. Indeed, flashing the previous kernel would restore the normal boot, so there had to be something wrong with my own kernel.
While looking at what the problem could be, I noticed that in the lavender
port the author did not modify the lineageos kernel config file in place, but
instead created a new one and changed the BoardConfig.mk file to point to his
new copy. Since it sounded like a good idea, I did the same and created
kernel/xiaomi/violet/arch/arm64/configs/vendor/violet_halium_defconfig for
the Halium changes. And then the line in the board config file became
TARGET_KERNEL_CONFIG := vendor/violet_halium_defconfig
I then continued investigating the boot issue, and I was told that it might
have been due to an Android option, skip_initramfs, which is set by the
bootloader and causes our Halium boot to fail. The fix is to just disable this
option in the kernel, by editing init/initramfs.c and change the
skip_initramfs_param function to always set the do_skip_initramfs variable
to 0, rather than to 1. After doing this, the boot proceeded to show the
Ubuntu splash screen with the five dots being lit, but it didn't proceed from
there.
Setting up the udev rules
Even in this state, the device was detected by my host PC and these lines appeared in the system log:
kernel: usb 1-3: new high-speed USB device number 26 using xhci_hcd kernel: usb 1-3: New USB device found, idVendor=0fce, idProduct=7169, bcdDevice= 4.14 kernel: usb 1-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3 kernel: usb 1-3: Product: Unknown kernel: usb 1-3: Manufacturer: GNU/Linux Device kernel: usb 1-3: SerialNumber: GNU/Linux Device on usb0 10.15.19.82
Indeed, I guess the reason I could do this without even flashing my systemimage is because I had first flashed another UT system image from another porter. I'm not sure if I'd had the same results with my own image. Anyway, the USB networking was there, so I connected and ran the following commands to generate the udev rules:
ssh phablet@10.15.19.82 # used 0000 as password sudo -i # same password again cd /home/phablet DEVICE=violet cat /var/lib/lxc/android/rootfs/ueventd*.rc /vendor/ueventd*.rc \ | grep ^/dev \ | sed -e 's/^\/dev\///' \ | awk '{printf "ACTION==\"add\", KERNEL==\"%s\", OWNER=\"%s\", GROUP=\"%s\", MODE=\"%s\"\n",$1,$3,$4,$2}' \ | sed -e 's/\r//' \ >70-$DEVICE.rules
I then copied (with scp) this file to my host PC, and I moved it to
device/xiaomi/violet/ubuntu/70-violet.rules (I had to create the ubuntu
directory first). Then I edited the device/xiaomi/violet/device.mk file and
added these lines at the end:
### Ubuntu Touch ### PRODUCT_COPY_FILES += \ $(LOCAL_PATH)/ubuntu/70-violet.rules:system/halium/lib/udev/rules.d/70-android.rules ### End Ubuntu Touch ###
It was now time to try my own system image. I rebooted my device into TWRP, I cloned the halium-install repository into my halium build dir, downloaded a rootfs for Halium9, and ran
./halium-install/halium-install -p ut \ ~/Downloads/ubuntu-touch-android9-arm64.tar.gz \ out/target/product/violet/system.img
The first time this failed because the simg2img tool was not installed. The
second time it proceeded to create the image, asked me for a password for the
phablet user (gave "0000") and pushed the image onto the device, into the
/data/ partition. I then rebooted.
My first Ubuntu Touch image
Upon reboot, the usual splash screen appeared, followed by several seconds of
black screen. It definitely didn't look right, but at least it proved that
something had been flashed. After some more seconds, to my big surprise, the
Ubuntu boot screen appeared, just with a smaller logo than how it used to be
before, which also confimed that my system image was being used — in fact, I
did not adjust the GRID_UNIT_PX variable before. Since this was an easy fix,
I chose to focus on that, rather than fix the boot issues (indeed, my device
did not move on from the Ubuntu boot screen). SSH was working.
I took the scaling.conf file from the lavender
changes,
put it in device/xiaomi/violet/ubuntu/ and added this line in the
PRODUCT_COPY_FILES in device.mk:
$(LOCAL_PATH)/ubuntu/scaling.conf:system/halium/etc/ubuntu-touch-session.d/android.conf
I initially used system/ubuntu/etc/... as the target destination for the
config file, like in the lavender commit, but this didn't work out for me. Then
I changed the path to start with system/halium/, like it's mentioned in the
ubports documentation, but it apparently had no effect either.
After a couple of days spent trying to understand why my files were not
appearing under /etc, it turned out that the device was not using my system
image at all: with halium-install I had my image installed in
/userdata/system.img, while the correct path for Halium 9 devices is
/userdata/android-rootfs.img. I was told that the option -s of
halium-install would do the trick. Instead of re-running the script, I took
the shortcut of renaming /userdata/system.img to
/userdata/android-rootfs.img and after rebooting I could see that the Ubuntu
logo was displayed at the correct size. And indeed my system image was being
used.
So I started to debug why unity8 didn't start. The logs terminated with this line:
terminate called after throwing an instance of 'std::runtime_error' what(): org.freedesktop.DBus.Error.NoReply: Message recipient disconnected from message bus without replying initctl: Event failed
It means, that unity8 did not handle correctly the situation where another
D-Bus service crashed while handing a call from unity8. The problem now was how
to figure out which service it was. I ran dbus-monitor and restarted unity8
(initctl start unity8), then examined the dbus logs; I saw the point where
unity8 got disconnected from the bus, but before that point I didn't find any
failed D-Bus calls. So it had to be the system bus. I did exactly the same
steps, just this time after running dbus-monitor --system as root, I found
the place where unity8 got disconnected, and found this D-bus error shortly
before that:
method call time=1605676421.968667 sender=:1.306 -> destination=com.ubuntu.biometryd.Service serial=3 path=/default_device; interface=com.ubuntu.biometryd.Device; member=Identifier method return time=1605676421.970222 sender=:1.283 -> destination=:1.306 serial=4 reply_serial=3 object path "/default_device/identifier" ... method call time=1605676421.974218 sender=:1.283 -> destination=org.freedesktop.DBus serial=6 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=GetConnectionAppArmorSecurityContext string ":1.306" error time=1605676421.974278 sender=org.freedesktop.DBus -> destination=:1.283 error_name=org.freedesktop.DBus.Error.AppArmorSecurityContextUnknown reply_serial=6 string "Could not determine security context for ':1.306'" ... signal time=1605676421.989074 sender=org.freedesktop.DBus -> destination=:1.283 serial=6 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=NameLost string "com.ubuntu.biometryd.Service" ... error time=1605676421.989302 sender=org.freedesktop.DBus -> destination=:1.306 error_name=org.freedesktop.DBus.Error.NoReply reply_serial=4 string "Message recipient disconnected from message bus without replying"
So, it looks like unity8 (:1.306) made a request to biometryd, who asked the
D-Bus daemon what was the AppArmor label of the caller, but since I didn't
backport the D-Bus mediation patches for AppArmor, the label could not be
resolved. biometryd decided to crash instead of properly handling the error,
and so did unity8.
So I backported the AppArmor patches. I took them from the Canonical kernel repo, but they did not apply cleanly because they are meant to be applied on top of a pristine 4.14 branch, whereas the Android kernel had already some AppArmor security fixes backported from later releases. So I set and quickly inspected the contents of each patch, and found out that a couple of them had already been applied, and the last patch had to be applied as the first (yeah, it's hard to explain, but it all depends on other patches that Android has backported from newer kernels). Anyway, after rebuilding the kernel and reflashing it, my phone could finally boot to unity8!
Conclusion (of the first episode)
The actual porting, as I've been told, starts here. What has been documented here are only the very first steps of the bring-up; what awaits me now is to make all the hardware subsystems work properly, and this, according to people more experienced in porting, is the harder part.
So far, very few things work, to the point that it's faster to me to list the things that do work; it's safe to assume that all what is not listed here is not working:
- Mir, with graphics and input: Unity8 starts and is usable
- Camera: can take photos; video recording start but an error appears when the stop button is pressed
- Flashlight
- Fingerprint reader: surprisingly, this worked out of the box
- Screen brightness (though it can be changed only manually)
For all the rest, please keep an eye on this blog: I'll write, when I make some progress!