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PortingToAndroid10 » History » Revision 264

Revision 263 (Denis 'GNUtoo' Carikli, 06/26/2020 10:12 PM) → Revision 264/287 (dl lud, 06/28/2020 10:06 AM)

h1. Porting Replicant to Android 10 9 

 {{>toc}} 

 

 h2. LineageOS 17 (Android 10) 

 The development is moving toward Android 10.  

 The basic features working on Replicant 9 have also been confirmed to work on Replicant 10, but not everything has been tested yet on either version. 

 At this point, the Replicant 9 source code is kept to do regression tracking, and the development has moved to Replicant 10. 

 h3. Building LineageOS 17 version 

 

 h4. Source code 

 <pre> 
 $ repo init -u https://git.replicant.us/replicant-9/manifest.git -b replicant-10-dev 
 $ repo sync 
 </pre> 

 Alternatively a shallow copy of the source tree can be fetched in order to save on disk space: 

 <pre> 
 $ repo init -u https://git.replicant.us/replicant-9/manifest.git -b replicant-10-dev --depth=1 
 $ repo sync -c 
 </pre> 

 To `unshallow` a specific module: 

 <pre> 
 $ cd path/to/module 
 $ git fetch --unshallow <remote> 
 </pre> 

 

 h4. For Trisquel 8 

 <pre> 
 sudo apt-get install bc bison build-essential bsdmainutils ccache curl flex g++-multilib gcc-multilib gettext git gnupg gperf imagemagick lib32ncurses5-dev lib32readline-dev lib32z1-dev liblz4-tool libncurses5-dev libsdl1.2-dev libssl-dev libwxgtk3.0-dev libxml2 libxml2-utils lzop python-mako pngcrush rsync schedtool squashfs-tools xsltproc zip zlib1g-dev 
 sudo apt-get install gcc-5-arm-linux-gnueabi 
 </pre> 

 

 h4. Launching the build 

 Not 100% sure if this is still needed: 
 <pre> 
 $ subject='/C=US/ST=California/L=Mountain View/O=Android/OU=Android/CN=Android/emailAddress=android@android.com' 
 $ mkdir .android-certs 
 $ for x in releasekey platform shared media testkey; do \ 
   ./development/tools/make_key .android-certs/$x "$subject"; \ 
   done 
 </pre> 

 To avoid the following error: 
 <pre> 
 16:20:13 See https://android.googlesource.com/platform/build/+/master/Changes.md#PATH_Tools for more information. 
 [    3% 2585/70375] build out/target/product/i9305/gen/STATIC_LIBRARIES/libmesa_nir_intermediates/nir/nir_builder_opcodes.h 
 FAILED: out/target/product/i9305/gen/STATIC_LIBRARIES/libmesa_nir_intermediates/nir/nir_builder_opcodes.h 
 /bin/bash -c "python external/mesa3d/src/compiler/nir/nir_builder_opcodes_h.py external/mesa3d/src/compiler/nir/nir_opcodes.py > out/target/product/i9305/gen/STATIC_LIBRARIES/libmesa_nir_intermediates/nir/nir_builder_opcodes.h" 
 Traceback (most recent call last): 
   File "external/mesa3d/src/compiler/nir/nir_builder_opcodes_h.py", line 106, in <module> 
     from mako.template import Template 
 ImportError: No module named mako.template 
 16:20:20 ninja failed with: exit status 1 
 </pre> 

 You need to run the following command: 
 <pre> 
 $ cd prebuilts/build-tools/path/linux-x86/ 
 $ rm python && ln -s /usr/bin/python python 
 </pre> 

 Then you can launch the build: 
 <pre> 
 $ parallel_tasks=$(echo "$(grep 'processor' /proc/cpuinfo | wc -l ) + 1" | bc) 
 $ source build/envsetup.sh 
 $ export TEMPORARY_DISABLE_PATH_RESTRICTIONS=true 
 $ lunch lineage_i9305-eng 
 $ make -j${parallel_tasks} bacon 
 </pre> 

 

 h4. Getting lastest changes 

 * The repositories are being constantly modified with git push --force as we are trying things out, and don't want to make the commits history look too dirty, so be sure to backup your local changes. 
 * Sometimes the manifest repository is also modified with git push --force. In that case the following commands will loose all the work you did locally but will make the repository consistent with upstream repositories again: 
 <pre> 
 $ rm -rf .repo/manifests/ # This enables me to force push and rebase the manifest repository as well 
 $ repo init -u https://git.replicant.us/replicant-9/manifest.git -b replicant-10-dev 
 $ repo sync --force-sync 
 </pre> 
 * The following command might also be necessary to make the state consistent with upstream repositories again, when the manifest history wasn't rewritten, but it will also loose all the work you did locally:  
 <pre> 
 $ repo sync --force-sync 
 </pre> 

 

 h4. Install the images 

 TODO 

 h4. Get adb 

 As the device IDs are the ones given by the Linux kernel, they are not in the adb udev rules, so for now it requires to run adb as root: 
 <pre> 
 $ sudo adb shell 
 * daemon not running; starting now at tcp:5037 
 * daemon started successfully 
 i9305:/ #                                  
 $ sudo adb kill-server 
 $ adb shell 
 * daemon not running; starting now at tcp:5037 
 * daemon started successfully 
 error: no devices/emulators found 
 </pre> 
 So make sure to kill the adb-server and run it as root: 
 <pre> 
 $ adb kill-server 
 $ sudo adb shell 
 * daemon not running; starting now at tcp:5037 
 * daemon started successfully 
 i9305:/ #  
 </pre> 

 

 h2. LineageOS 16 (Android 9) 

 h3. Repositories and changes for LineageOS 16 

 * https://git.replicant.us/GNUtoo/kernel_replicant_linux.git 
 * git://git.putti.eu/aosp/external_mesa3d.git 
 * https://git.replicant.us/GNUtoo/android_build.git 
 * https://git.replicant.us/GNUtoo/device_i9305.git 
 * https://git.replicant.us/GNUtoo/manifest.git 
 * https://git.replicant.us/GNUtoo/vendor_replicant.git 

 h3. Building LineageOS 16 version 

 h4. Source code 

 <pre> 
 $ repo init -u https://git.replicant.us/replicant-9/manifest.git -b replicant-9 
 $ repo sync 
 </pre> 

 Alternatively a shallow copy of the source tree can be fetched in order to save on disk space: 

 <pre> 
 $ repo init -u https://git.replicant.us/replicant-9/manifest.git -b replicant-9 --depth=1 
 $ repo sync -c 
 </pre> 

 To `unshallow` a specific module: 

 <pre> 
 $ cd path/to/module 
 $ git fetch --unshallow <remote> 
 </pre> 

 h4. For Trisquel 8 

 <pre> 
 sudo apt-get install bc bison build-essential bsdmainutils ccache curl flex g++-multilib gcc-multilib gettext git gnupg gperf imagemagick lib32ncurses5-dev lib32readline-dev lib32z1-dev liblz4-tool libncurses5-dev libsdl1.2-dev libssl-dev libwxgtk3.0-dev libxml2 libxml2-utils lzop python-mako pngcrush rsync schedtool squashfs-tools xsltproc zip zlib1g-dev 
 sudo apt-get install gcc-5-arm-linux-gnueabi 
 </pre> 

 h4. Launching the build 

 Follow the "i9300 manifest instructions:":https://github.com/CustomRoms/android_local_manifests_i9300 
 <pre> 
 $ subject='/C=US/ST=California/L=Mountain View/O=Android/OU=Android/CN=Android/emailAddress=android@android.com' 
 $ mkdir .android-certs 
 $ for x in releasekey platform shared media testkey; do \ 
   ./development/tools/make_key .android-certs/$x "$subject"; \ 
   done 
 $ parallel_tasks=$(echo "$(grep 'processor' /proc/cpuinfo | wc -l ) + 1" | bc) 
 $ source build/envsetup.sh 
 $ lunch lineage_i9305-eng 
 $ make -j${parallel_tasks} bacon 
 </pre> 

 The images can then be flashed with heimdall. They are then in: 
 <pre> 
   out/target/product/i9305/obj/PACKAGING/target_files_intermediates/lineage_i9305-target_files-eng.replicant/IMAGES/ 
 </pre> 

 h4. Getting lastest changes 

 * The repositories are being constantly modified with git push --force as we are trying things out, and don't want to make the commits history look too dirty, so be sure to backup your local changes. 
 * Sometimes the manifest repository is also modified with git push --force. In that case the following commands will loose all the work you did locally but will make the repository consistent with upstream repositories again: 
 <pre> 
 $ rm -rf .repo/manifests/ # This enables me to force push and rebase the manifest repository as well 
 $ repo init -u https://git.replicant.us/replicant-9/manifest.git -b replicant-9 
 $ repo sync --force-sync 
 </pre> 
 * The following command might also be necessary to make the state consistent with upstream repositories again, when the manifest history wasn't rewritten, but it will also loose all the work you did locally:  
 <pre> 
 $ repo sync --force-sync 
 </pre> 

 h4. Install the images 

 <pre> 
 $ sudo heimdall flash --BOOT out/target/product/i9305/obj/PACKAGING/target_files_intermediates/lineage_i9305-target_files-eng.replicant/IMAGES/boot.img --USERDATA out/target/product/i9305/obj/PACKAGING/target_files_intermediates/lineage_i9305-target_files-eng.replicant/IMAGES/userdata.img --SYSTEM out/target/product/i9305/obj/PACKAGING/target_files_intermediates/lineage_i9305-target_files-eng.replicant/IMAGES/system.img  
 </pre> 

 h4. Get adb 

 As the device IDs are the ones given by the Linux kernel, they are not in the adb udev rules, so for now it requires to run adb as root: 
 <pre> 
 $ sudo adb shell 
 * daemon not running; starting now at tcp:5037 
 * daemon started successfully 
 i9305:/ #                                  
 $ sudo adb kill-server 
 $ adb shell 
 * daemon not running; starting now at tcp:5037 
 * daemon started successfully 
 error: no devices/emulators found 
 </pre> 
 So make sure to kill the adb-server and run it as root: 
 <pre> 
 $ adb kill-server 
 $ sudo adb shell 
 * daemon not running; starting now at tcp:5037 
 * daemon started successfully 
 i9305:/ #  
 </pre> 

 h4. Booting 

 At some point during boot, the device goes into suspend, so you will need to press some buttons like the power or volume button to make the boot continue until the graphical interface. 

 You can also follow the boot progress with adb: 
 <pre> 
 adb logcat 
 adb logcat -b main 
 </pre> 

 Note that the device can go into suspend at any time, so adb might be interrupted. That looks like that: 
 First you get a shell 
 <pre> 
 $ sudo adb shell 
 i9305:/ # 
 </pre> 

 Then the connection is interrupted: 
 <pre> 
 $ adb shell 
 i9305:/ # [randomdev@fullyfreelaptop ]$                                                                                                      
 </pre> 

 The effect with adb logcat is similar. 

 h3. cleanups to be done 

 * Make adb work as user by using the right USB IDs, and make userspace do the USB setup. 
 * -Make the kernel not use hardcoded CMDLINE_FORCE- Not possible unless the bootloader is changed or Linux is very heavily patched. 
 * Make the kernel not use hardcoded partitions if possible (though we use system as root) 
 * Make a clean Gatekeeper HAL module implementation instead of using the same hack than goldfish 
 * look at "init.rc":https://android.googlesource.com/platform/system/core/+/master/init/README.md documentation to see if init.rc can be overriden clearly with the override statement to see if it's possible to keep the serial console patch for -eng 

 h3. Using SwiftShader instead of Mesa3D llvmpipe for software rendering 

 To use SwifShader you need a kernel that supports UDIV/SDIV emulation, you can checkout the branch GNUtoo/udiv-emulation for kernel/replicant/linux. After doing that that run the following commands to use SwiftShader: 

 <pre> 
 $ adb remount 
 $ adb shell 
 i9305:/ # rm vendor/lib/egl/libGLES_mesa.so # or move it somewhere safe meanwhile you test SwiftShader 
 i9305:/ # nano system/build.prop # set ro.hardware.hwcomposer=ranchu and ro.hardware.gralloc=default 
 $ adb reboot 
 </pre> 

 

 h2. AOSP 9 

 h3. Status with AOSP 9 

 * The Galaxy SIII 4G (i9305) boots (with graphics hacks) under AOSP9, without having to import nonfree libraries: 
 ** The device boots until the lock screen 
 ** The graphics work but are really slow as they have not been optimized 
 ** Sometime the display content is corrupted 
 ** The touchscreen works 
 * The kernel used is based on Linux 5.0-rc6 and has ~150 Android specific patches on top and some patches for the Galaxy SIII 4G (i9305) on top 

 h3.    Repositories and changes 
 
 * git://git.putti.eu/aosp/manifest_i9305.git 
 * git://git.putti.eu/aosp/kernel_i9305.git 
 * git://git.putti.eu/aosp/device_i9305.git 
 * git://git.putti.eu/aosp/external_mesa3d.git 
 * git://git.putti.eu/aosp/build_make.git 
 * git://git.putti.eu/aosp/core.git 

 h3. Building AOSP version 

 h4. Source code 

 First get the source code: 
 <pre> 
 $ repo init -u git://git.putti.eu/aosp/manifest_i9305.git -b android-9.0.0 
 </pre> 

 h4. For Trisquel 8 

 <pre> 
 sudo apt-get install git-core gnupg flex bison gperf build-essential zip curl zlib1g-dev gcc-multilib g++-multilib libc6-dev-i386 lib32ncurses5-dev x11proto-core-dev libx11-dev lib32z-dev libgl1-mesa-dev libxml2-utils xsltproc unzip bc python-mako gcc-5-arm-linux-gnueabi 
 </pre> 

 h4. Building it 

 Once this is done, see the device/putti/i9305/README.md for the build instructions. 

 h4. Trisquel 8 LXC 

 If you use Parabola, you may be interested in running Trisquel 8 in LXC. 

 To do that first debootstrap a Trisquel 8 rootfs.  

 Parabola's debootstrap does support Trisquel 8 and its manual has an example on how to do that: 
 <pre> 
 $ man debootstrap 
 [...] 
 # debootstrap flidas flidas-root http://archive.trisquel.info/trisquel 
 </pre> 

 Then you can use virt-manager to setup the LXC instance. 

 The advantages of this solution are that: 
 * The LXC guest and host shares their resources (CPU, RAM) with almost no penalty 
 * Trisquel 8 is not a rolling release distribution 

 The disadvantage of this solution are that: 
 * you need to configure again the Trisquel 8 LXC instance (vimrc, sshd_config, etc) 
 * It's more complicated to setup 
 * The Android build system output a warning message about not being able to use namespaces which may become mandatory in newer Android versions 

 

 h2. Upstreaming status 

 * The stock bootloader is incompatible with Linux, see [[BootloadersIncompatibleWithLinux#Devices-with-the-Exynos-4412]] for more information. So we maintain patches to enable the Galaxy SIII, and Galaxy Note II to boot with the stock bootloader. In the long run we need to look into using u-boot in the kernel partition as using u-boot instead of the stock bootloader currently require nonfree and non-redistributable software (BL1). 
 * For the patches that are not merged yet, see the "issues of the redmine upstreaming sub-project":https://redmine.replicant.us/projects/upstreaming/issues 

 

 h2. Modem status 

 *libsamsung-ipc:*  
 * Fully tested under GNU/Linux only 
 * Can initialize completely the modem and receive messages (see the #1954 bug report for the logs) 
 * Needs more cleanup but there is now a better abstraction 

 *libsamsung-ril:*  
 * Ported to Replicant 9 using a wrapper for the API >=12 in libsamsung-ril source code that needs to be removed 
 * Tested under Replicant 9 without up to date libsamsung-ipc (no modem init) 
 * Tested and validated under Replicant 6 (doesn't break telephony) 

 h3. Modem status TODO 

 * Implement the missing part to shut down the modem, close the interfaces and such, in order to need to reboot after each test. 
 * Continue to clean up the libsamsung-ipc and libsamsung-ril patches, test the patches in Replicant 6 when applicable, and merge them in the upstream repositories. 
 * Convert the firmware loading driver to the upstream API and then adapt libsamsung-ipc for that. This should also benefit other devices like the Galaxy SIII 4G, and the Galaxy Note II 4G which probably don't need much more to get their modem supported by upstream Linux. 
 * Cleanup and convert the rest of the drivers to look like the ones for the Nokia N900 and adapt the userspace in libsamsung-ipc, and merge libsamsung-ipc support for that once the kernel API is stable. 
 * Test the code under Replicant 9 when the graphics status will enable to have decent enough speed to do some testing through human interaction. 

 

 h2. TODO 

 First month of full time equivalent work: 

 |_. Time estimation    |_.Task |_. Comments | 
 | DONE | -boot a device under AOSP9- | Only boots with graphics, not much more | 
 | -7h- DONE | -build it under a "FSDG compliant distribution":https://www.gnu.org/distros/free-distros.html like Trisquel8- | -WIP for AOSP, It's difficult to do precise time estimations as it could work out of the box or require one full time month of work depending on how much issues are encountered-  
 Builds under Trisquel8| 
 | -21h- DONE | * -port the changes from AOSP9 to LineageOS 16- 
 * -cleanup the code- 
 * -build the kernel from the Android build system- 
 * -make sure it builds with an FSDG compliant distribution- 
 * -document the build procedure- | 
 Status: 
 * Boots with adb. 
 * Has ultra slow graphics | 
 | 14h | find, remove and document proprietary software in LineageOS 16 | | 
 | 21h | find, remove and document privacy issues in LineageOS 16 | | 
 | 7h | -Add support for the touch keys driver in the    galaxy-s3 dts- | "applied":https://lists.infradead.org/pipermail/linux-arm-kernel/2019-November/694100.html | 
 | 7h | -upstream the AAT1290 flash led Linux dts for the galaxy-s3 boards- | "Now in 5.3":https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.3&id=4e4dfcb2a425cccc6dd1fb7d46e060cd57999afc | 
 | 7h | rebrand LineageOS as Replicant | | 
 | 70h | -port and- cleanup the the Galaxy SIII (i9300) "modem":https://github.com/fourkbomb/linux/tree/modem Linux driver from 4.16 to 5.0| See the [[PortingToAndroid9/#Modem-status|modem status]] for more details | 
 |_\3. Total: 147h (~1 month) | 

 Second month of full time equivalent work: 
 | * port    libsamsung-ril and libsamsung-ipc to Android 9 
 * Make the modem driver and libsamsung-ipc work together | 157h | See the [[PortingToAndroid9/#Modem-status|modem status]] for more details | 
 |_. Total |_. 157h | ~1 month | 

 Third month of full time equivalent work: 
 |_. Task |_. Time estimation |_. Comments | 
 | -port the sensors libraries and other device specific libraries- 
 Look which sensor libraries can be used | 70h | Already done by the unofficial LineageOS port of the Galaxy SIII (i9300), needs testing | 
 | add support for Audio with the upstream kernel driver | 70h | Might be way faster, depending on what Android 9 uses 
                                                                See also "this bugreport":https://github.com/CustomROMs/android_local_manifests_i9300/issues/1 | 
 | -add partial (no modem) support for the Galaxy SIII 4G (i9305) and- factorize the code with i9300 | 14h | * The source code on which the work was based changed from AOSP to an unofficial LineageOS port to a port of i9305 support for AOSP by Joonas to the official LineageOS so it's now supported by default 
 * The work to factorize the code between the i9300 and i9305 still need to be done | 
  | 
 |_. Total |_. 154h | ~1 month | 

 |_. Task |_. Time estimation |_. Comments | 
 | create a recovery | 21h | | 
 | add internal WiFi support and validate the functionality | 6h | | 
 | add external WiFi dongles support | 20h | External dongles support might be tricky | 
 | -create new- update the install and upgrade instructions | -35h- | -Our current install instructions don't scale as we have one copy for each device.- 
 -We also created generic instructions but they tend to be harder to follow[1] than the device specific ones.- 
 -This will be made in a modular format (for instance in LaTeX) that enables to generate per device install instructions without requiring to have multiples copy of the same text.- 
 -The instructions will need to be able to be modified and compiled on an FSDG compliant distribution.- 
 Mostly done:  
 * The installation instructions are now generic enough.  
 * Some long standing TODO were also done along the way like adding backup instructions for the EFS. 
 * The current instructions are still for Replicant 6.0 and will need to be updated for Replicant 9.0 | 

 |_. Task |_. Time estimation |_. Comments | 
 | Estimate the amount of work to Reduce the attack surface | ? | | 
 | Estimate the amount of work to add in-system upgrades | ? | | 

 fn1. The generic instructions were tested at Install parties in Paris  

 h3. Devices support: 

 h4. Easy, because it's similar enough to the Galaxy SIII (I9300) 

 |_\3. Galaxy Note II (N7100) | 
 |_. Task |_. Time estimation |_. Comments | 
 | port the EA8061 LCD Linux driver | 35h | | 
 | port the S6EVR02 LCD Linux driver | 35h | | 
 | port the MAX77693 flash led Linux driver | 7h | | 
 | android: add support for the Note II (N7100) and factorize the code with Galaxy SIII (i9300) and Galaxy SIII 4G (i9305) | 14h | Should be similar to the Galaxy SIII | 
 | port the sensors libraries and other device specific libraries | 70h | It's difficult to evaluate how much time it could take | 
 | add support for Audio with the upstream kernel driver | 14h | Should be similar to the Galaxy SIII | 

 |_\3. Galaxy Note 8.0 (N5100) and 8.0 WiFi (N5110) | 
 |_. Task |_. Time estimation |_. Comments | 
 | Evaluate the time required to do the port | 14h | TODO | 

 h4. Needs more work and unknown upstream Linux status 

 |_. Device |_. Time estimation |_. Comments | 
 | Galaxy S II (i9100) | | Linux: devboard dts upstream? unknown status | 
 | Galaxy Note (N7000) | | unknown Linux upstream status | 
 | Galaxy Nexus (I9250) | |/2. OMAP4, no dts upstream | 
 | Galaxy Tab 2 7.0 (P3100), 7.0 WiFi (P3110), 10.1 (P5100), 10.1 WiFi (P5110) | | 
 | GTA04 >= A4 | | TODO: a RIL needs to be written, userspace GPS support is missing, audio scenarios, etc | 

 

 h2. Documentation 

 

 h3. Replicant 6.0 changes 

 See [[Replican6Changes]]. 

 

 h3. Other rebases 

 See the [[Samsung-ipc]] page. 

 

 h2. Other attempts 

 * It might be interesting to contact the people doing ports once we have something working well enough. 
 * It is also interesting to look at other attempts to understand if a given device is powerful enough to run Android 9 and what configuration was used to achieve it. 

 |_. Device(s) |_. Repository |_. status |_. Comments | 
 | i9300 | "CustomROMs":https://github.com/CustomROMs/android_local_manifests_i9300 | * "March 3 2019 release":https://forum.xda-developers.com/galaxy-s3/development/rom-lineageos-16-0-t3875899 | | 
 | i9300 | "Team InFusion":https://github.com/team-infusion-developers/android_local_manifests_i9300 | * "August 20 2019 release":https://forum.xda-developers.com/galaxy-s3/development/rom-optimized-lineageos-16-0-team-t3940142 | Issues: * Uses a Samsung kernel 
 * Uses too many nonfree libraries 
 => Probably nothing we could reuse from its code | 
 | N7100 | "ComicoTeam":https://github.com/ComicoTeam/android_device_samsung_n7100 | * "September 13 2019 release":https://forum.xda-developers.com/galaxy-note-2/development/rom-lineageos-16-0-20190112-comico-t3889281 | | 
 | I9100 | | "XDA":https://forum.xda-developers.com/galaxy-s2/development-derivatives/pie-i9100-t3850588 | | 

 h3. Links for other attempts 

 * https://www.xda-developers.com/android-pie-android-9-port-custom-roms/ 

 h3. CustomROMs i9300 components 

 |_. Repository |_. Tree path |_. Dependencies |_. Function |_. Comments | 
 |/8. https://github.com/CustomROMs/android_hardware_samsung 
 lineage-16.0 branch | hardware/samsung/macloader | | Loads the MAC Address of the WiFi network interface | Might be useful | 
 | hardware/samsung/wifiloader | | Loads the wifi kernel module (like modprobe) and setup firmware filesystems permissions | May be useful | 
 | hardware/samsung/audio | | seems to contains ril related stuff as well | Look if the ril stuff is required, go for standard audio | 
 | hardware/samsung/lineagehw/hidl/livedisplay | | livedisplay is a feature similar to what redshift does on GNU/Linux | Not sure if it works with mainline | 
 | hardware/samsung/exynos/multimedia/utils/ | seem meant for audio/video decoding offload | assembly obtimized color conversion and resize code | check assembly code license, not sure if useful | 
 | all other directories in hardware/samsung/exynos/ | nonfree firmwares, nonfree software?, smdk kernel? | audio/video decoding offload | Avoid using that | 
 | hardware/samsung/exynos3 |/2. nonfree firmwares?, nonfree software?, smdk kernel? |/2. some light libraries, display stuff (gralloc, etc), 2D acceleration (FIMG), camera (FIMC), 3D acceleration, etc |/2. Avoid using that for now | 
 | hardware/samsung/exynos4 | 

 

 h2. Links  

 * "Android build requirements - hardware and software":https://source.android.com/setup/build/requirements 
 * "Why LineageOS Developers are building Android Go-optimized custom ROMs":https://www.xda-developers.com/android-go-old-android-8-1-oreo/ 
 * "Android Go recommended default values for propreties for optimization":https://android.googlesource.com/platform/build/+/master/target/product/go_defaults_common.mk 
 * "Team InFusion i9300 optimized system.prop":https://github.com/team-infusion-developers/android_device_samsung_i9300/blob/lineage-16.0/system.prop#L23 
 * "Hack to fix high CPU usage caused by logd":https://github.com/team-infusion-developers/android_device_samsung_smdk4412-common/commit/c66015514fc9779edfed2665f67e841f3620c71e 
 * "Use low-end video codecs":https://github.com/team-infusion-developers/android_device_samsung_smdk4412-common/commit/adc919f04b981a4fe005fab2cf443596a22992b2 
 * "Optimize ActivityManager cached apps":https://github.com/team-infusion-developers/android_device_samsung_smdk4412-common/commit/24bc62970d35eb5a7a257463e7dbfe873ceb5779 
 * "Use 1Gb Dalvik config":https://github.com/team-infusion-developers/android_device_samsung_smdk4412-common/commit/8a7cebc5af772a2949420ac4a383f5f75236c65c