Porting to a new device
- 1 Introduction
- 2 Preparation
- 3 Requirements
- 4 Initialization
- 5 Kernel package
- 5.1 APKBUILD file
- 5.2 Source code
- 5.3 Kernel version
- 5.4 Defconfig
- 5.5 Download sources and update checksums
- 5.6 Kernel configuration
- 5.7 Kernel compilation
- 5.8 Find the error message
- 5.9 Get a patch
- 5.10 Changing compiler
- 5.11 Device specific package
- 6 We are happy to help you!
- 7 Documentation
- 8 Installation
- 9 Flashing
- 10 Alternatives to regular flashing
- 11 USB Network
- 12 Upstreaming
- 13 Display
- 14 Touchscreen
- 15 Changing your installation
- 16 Full disk encryption: osk-sdl support
- 17 Advanced topics
This is a step by step guide made for you to be able to port postmaketOS to a new device.
The main steps are:
- Set up postmarketOS development environment on your computer.
- Build a device-specific kernel and a device-specific system package for your device.
- Install the system and adapt it according to your device and usage.
For help, simply connect to the main Matrix/IRC channel and kindly drop your question. People are happy to answer your questions!
To set up a development environment, you will need a GNU/Linux system capable of making builds and running pmbootstrap, our development and installation tool. If you don't have a Linux-based OS installed, you may want to set up a virtual machine with VirtualBox first.
Your GNU/Linux system must have:
- A few gigabytes of free space
- Linux kernel 3.17 or newer (since earlier Linux kernels do not support the
It is recommended that you at least somewhat know how to use Linux distributions and how to build software as the porting process is a bit harder than just running a few commands.
If your target device has an ARM processor, it must have a floating-point unit (FPU). If the device has at least an ARMv7 CPU, it should have an FPU; however, only some ARMv6 CPUs have one.
Most smartphones have an FPU. Of the first 80+ ports that we started, only two phones lacked an FPU: the HTC Wildfire from 2010 (#1203) and the Vodafone 858 Smart from 2011 (#1592)). Both phones use the MSM7225, an ARMv6 SoC. If your phone was made before 2012, make sure it has an FPU.
Install pmbootstrap, our lightweight postmarketOS development and installation tool. Then run the following:
$ pmbootstrap init Location of the 'work' path. Multiple chroots (native, device arch, device rootfs) will be created in there. Work path [/home/user/.local/var/pmbootstrap]:
Type in the code name of your device to start a new port, and answer each prompt. For help, see how to find device-specific information.
Target device (either an existing one, or a new one for porting). Available (60): asus-flo, asus-grouper, fairphone-fp2, ... Device [samsung-i9100]: wiki-example You are about to do a new device port for 'wiki-example'. Continue? (y/n) [y]: Device architecture (armhf/armv7/aarch64/x86_64/x86) [armhf]: armv7 Who produced the device (e.g. LG)? Manufacturer: Samsung What is the official name (e.g. Google Nexus 5)? Name: Wiki Example Does the device have a hardware keyboard? (y/n) [n]: Does the device have a sdcard or other external storage medium? (y/n) [n]:
It depends on the flashing protocol, that comes with the device. For most Android devices, this is
fastboot, some Samsung models need
heimdall (which is compatible to "Odin") and Maemo/MeeGo-based Nokia phones work with
0xffff. If you don't know which one it is, try to enter the bootloader on your device and check whether it says "Fastboot mode" or "Odin mode". Most of the time, that can be done by pressing the
Volume Down key when it is just booting. In case you can't figure that one out, try to search the internet - there might even be videos on YouTube on how to do that if you're lucky.
For more information see the Wiki page about Deviceinfo flash methods.
Which flash method does the device support? Flash method (fastboot/heimdall/0xffff) [fastboot]:
Depending on your selection,
pmbootstrap may ask you to analyze a
boot.img file to get offset values required for the flash method. Get the right one for your device from TWRP (
twrp-*.img), LineageOS (
boot.img inside the zip archive) or by extracting it from within a running Android. If you can't find any, you can skip this step for now by just pressing the return key.
You can analyze a known working boot.img file to automatically fill out the flasher information for your deviceinfo file. Either specify the path to an image or press return to skip this step (you can do it later with 'pmbootstrap bootimg_analyze'). Path: /home/user/Downloads/twrp-3.2.0-0-mako.img NOTE: You will be prompted for your sudo password, so we can set up a chroot to extract and analyze your boot.img file (native) install alpine-base (native) install file unpackbootimg
We recommend, that you start with
weston first, because that has been around the longest in postmarketOS and, while it is not really suitable for a phone, it works as a stable demo interface for making the graphics output work in the first place. After that one works, feel free to try out another interface (but expect, that it will not necessarily work out of the box).
Username [user]: Available user interfaces (5): * none: No graphical environment * hildon: (X11) Lightweight GTK+2 UI (optimized for single-touch touchscreens) * luna: (Wayland) webOS UI, ported from the LuneOS project (Not working yet) * plasma-mobile: (Wayland) Mobile variant of KDE Plasma, optimized for touchscreen * weston: (Wayland) Reference compositor (demo, not a phone interface) * xfce4: (X11) Lightweight GTK+2 desktop (stylus recommended) User interface [weston]: Build options: Parallel jobs: 3, ccache per arch: 5G Change them? (y/n) [n]: Additional packages that will be installed to rootfs. Specify them in a comma separated list (e.g.: vim,file) or "none" Extra packages [none]: Your host timezone: Europe/London Use this timezone instead of GMT? (y/n) [y]: WARNING: The applications in the chroots do not get updated automatically. Run 'pmbootstrap zap' to delete all chroots once a day before working with pmbootstrap! It only takes a few seconds, and all packages are cached. Done!
Open a second terminal and run the following command to see detailed logging (such as compiler output). Whenever reporting, that something does not work, please attach the detailed log output from this window.
$ pmbootstrap log
While the goal is to use a mainline kernel for all devices in the long run, this certainly can not be done in one step when porting to a new device. What we do in the meantime is shipping a Linux kernel fork, that is known to work with this device (e.g. from Android).
The steps below are the straight forward changes you need to compile your kernel. For details see the vendor kernel specific package article.
APKBUILD file is a script used to build a package. There are two APKBUILDs you have to edit: for device and linux packages related to your port. The APKBUILDs located at packages' folders.
Where to find device-related packages folders?
In case you cloned pmbootstrap from git:
In case you have not cloned pmbootstrap from git:
Where $workdir is the path you provided at the first step of
pmbootstrap init process and "wiki-example" by the brand and codename you provided there.
Find the source code of the known working kernel fork. Try to find a widely used kernel if possible, for example from LineageOS. The kernel version is also important, as of writing (April 2020), the lowest kernel version number we have packaged is 3.0.x. It might be possible to get even older kernels running (with old GCC versions), but even if you get them to boot, you will likely run into problems down the road.
Once you have your kernel, adjust the
# Source section in the
linux-wiki-example/APKBUILD file. For LineageOS kernels, you will only need to change
_commit variables. Usually it makes sense to use a commit from the most recently updated branch. For example, if the kernel repo is at
https://github.com/LineageOS/android_kernel_motorola_ghost.git, you would use
_commit="c4914db2f65ef63548b0af5d7b37d131581c9c62" (find the commit by clicking on c4914db2 next to "Latest commit" at the top right corner of the directories box).
If your kernel is not in a LineageOS repository but somewhere else, you also have to change the URL in
source accordingly, e.g. to
https://github.com/jmrohwer/$_repository/archive/$_commit.tar.gz if the kernel is in
https://github.com/jmrohwer/TF101-GNU-kernel. You still need to set
_commit as described above.
If your kernel is only available as archive (zip, tarball, etc.), you can unpack it and use
pmbootstrap build linux-wiki-example --src=/path/to/extracted/kernel/source for now. Later on, when it's time to upstream your work into the official postmarketOS repositories so everybody can use it, talk to us so we can publish the kernel in a good place.
Do not fork the kernel and add patches there. There are already enough Linux kernel forks out there, and it's next to impossible to understand which kernel repository has which patches applied. Let's not make the situation worse with creating another fork with random patches on top, just to make it compile with postmarketOS. Instead, point to the kernel you found. All postmarketOS specific patches should be applied as patch files in the same directory as the APKBUILD. How this is done exactly is described further below in the porting guide. When doing it like that, we avoid downloading the huge kernel sources every time a new patch is applied (remember that not everybody in the world has fast Internet connections), and it makes it much more transparent as the actual patches show up in code reviews.
Consider the reliability of the kernel source. If there is any chance that the source might disappear, a backup must be taken and used instead of the original source. See How to properly backup downstream kernels for instructions.
_flavor="wiki-example" # be sure it's in form of <vendor-codename>, e.g. motorola-ghost # Source _repository="(CHANGEME!)" # e.g. android_kernel_motorola_ghost _commit="ffffffffffffffffffffffffffffffffffffffff" # e.g. c4914db2f65ef63548b0af5d7b37d131581c9c62 _config="config-$_flavor.$arch" source=" $pkgname-$_commit.tar.gz::https://github.com/LineageOS/$_repository/archive/$_commit.tar.gz $_config gcc7-give-up-on-ilog2-const-optimizations.patch gcc8-fix-put-user.patch " builddir="$srcdir/$_repository-$_commit"
In the repository with the kernel source code, you will find a
Makefile. Open this file and adjust the
pkgver in the kernel
APKBUILD to the information from the
SUBLEVEL variables (e.g. 3.4.0).
Next you will need to find the kernel configuration, that is used to compile that kernel source for your device. Download it and save it as
$ wget https://github.com/LineageOS/lge-kernel-mako/raw/cm-14.1/arch/arm/configs/lineageos_mako_defconfig $ mv lineageos_mako_defconfig aports/device/testing/linux-wiki-example/config-wiki-example.armhf
Download sources and update checksums
Use the checksum command. It will not only generate the checksums of all source files, but also download them in case they have not been downloaded yet. If this command fails, most likely the download URL is invalid and needs to be adjusted in the
APKBUILD again. Another cause could be, that the defconfig could not be found (e.g. because it was saved with a wrong file name). The actual download URL (with all variables replaced) and the download progress are visible in the log window.
$ pmbootstrap checksum linux-wiki-example
The magic command, which lets you change the kernel configuration is
pmbootstrap kconfig edit. Don't try to manually change the defconfig file, because only by running menuconfig, the dependencies will get resolved properly.
menuconfig always runs on the kernel with all patches applied, so we'll run it once to see if we need to remove patch files first.
If there are no errors, you can exit menuconfig with ESC-ESC and move on to making kconfig check happy.
Remove failed patches
You will find some example patches already in the generated kernel package. When a patch does not apply correctly, you will get something like the following in the log window (scroll up, the error is above the
$ pmbootstrap kconfig edit
>>> linux-wiki-example: Unpacking /var/cache/distfiles/linux-wiki-example-ffff.tar.gz... >>> linux-wiki-example: 01_msm-fix-perf_trace_counters.patch patching file arch/arm/mach-msm/perf_trace_counters.h Hunk #1 succeeded at 158 (offset 37 lines). >>> linux-wiki-example: 02_this_patch_fails.patch patching file arch/arm/mach-msm/perf_trace_counters.h Hunk #1 FAILED at 121. 1 out of 1 hunk FAILED -- saving rejects to file arch/arm/mach-msm/perf_trace_counters.h.rej >>> ERROR: linux-wiki-example: all failed
When this happens, remove the failing patch from the
source= variable in the
APKBUILD, and delete the patch file from the same folder. Finally, correct the checksums and try kconfig edit again.
$ nano aports/device/testing/linux-wiki-example/APKBUILD # remove from source $ rm aports/device/testing/linux-wiki-example/02_this_patch_fails.patch $ pmbootstrap checksum linux-wiki-example $ pmbootstrap kconfig edit
Make kconfig check happy
Check what you need to adjust in the kernel config before it can be used with postmarketOS. Keep changing the options, until everything passes.
$ pmbootstrap kconfig check $ pmbootstrap kconfig edit $ pmbootstrap kconfig check
Next up is the kernel compilation, which will fail a few times before you get it working. Run it once to see where it fails.
$ pmbootstrap build linux-wiki-example
We most likely use a more modern version of GCC compared to what your device kernel was intended to be compiled with (which is good, we don't want outdated software). However, this means that you will probably need to patch your kernel before it compiles successfully. Don't be scared, we'll talk you through it. But in the unlikely case, that everything runs through smoothly, continue reading here.
Find the error message
To find the error message, you should open a log file in your favorite text editor, like
$ nano $(pmbootstrap config work)/log.txt
and use search to find error messages for the last build run (they contain
Examples of errors:
In file included from arch/arm/mach-msm/perf_trace_counters.h:127:0, from arch/arm/mach-msm/perf_trace_counters.c:14: include/trace/define_trace.h:79:43: fatal error: ./perf_trace_counters.h: No such file or directory
drivers/built-in.o: In function `.LANCHOR1': msm_iommu_sec.c:(.data+0x9298): undefined reference to `kgsl_iommu_sync_lock' msm_iommu_sec.c:(.data+0x929c): undefined reference to `kgsl_iommu_sync_unlock' Makefile:877: recipe for target '.tmp_vmlinux1' failed make: *** [.tmp_vmlinux1] Error 1
It is possible to clear the log file right before compilation, when you press
(old log output here) ^C $ pmbootstrap log -c
Another trick to find the error message real quick, is to open
less and use the follow mode (press while in
less or open less with the
less +F log.txt). This causes
less to behave like
tail -f. When an error occurs, you can exit the follow mode by pressing + and use to reverse search the output (for example:
?error). Press to re-enable follow mode.
Get a patch
From postmarketOS aports
It is highly likely, that we already ran into the same issue with another kernel. Take (parts of) the offending file name and search for it inside
$ grep -r 'perf_trace_counters\.c' aports/device/ aports/device/testing/linux-lg-mako/01_msm-fix-perf_trace_counters.patch:In-tree compilation for arch/arm/mach-msm/perf_trace_counters.c was aports/device/testing/linux-lg-mako/01_msm-fix-perf_trace_counters.patch: from arch/arm/mach-msm/perf_trace_counters.c:14 $ grep -r 'msm_iommu_sec' aports/device/ aports/device/testing/linux-lg-mako/02_gpu-msm-fix-gcc5-compile.patch:msm_iommu_sec.c:(.data+0x9298): undefined reference to `kgsl_iommu_sync_lock' aports/device/testing/linux-lg-mako/02_gpu-msm-fix-gcc5-compile.patch:msm_iommu_sec.c:(.data+0x929c): undefined reference to `kgsl_iommu_sync_unlock'
When there is a result, copy the patch file you found to your new kernel package, add it to the
source variable in the
APKBUILD and try building again.
$ cp aports/device/testing/linux-lg-mako/01_msm-fix-perf_trace_counters.patch aports/device/testing/linux-wiki-example/ $ nano aports/device/testing/linux-wiki-example/APKBUILD # add it to source $ pmbootstrap checksum linux-wiki-example $ pmbootstrap build linux-wiki-example
Fire up your favorite search engine, and look at all results for the error message and variations of it. The
"" feature of most search engines is useful, so it searches for an exact string and not single words. Example queries for the error messages above:
include/trace/define_trace.h: fatal error: ./perf_trace_counters.h: "No such file or directory"
linux "./perf_trace_counters.h: No such file or directory"
android "undefined reference to `kgsl_iommu_sync_unlock'"
In most cases, this will yield a patch that you can apply to your kernel. Save what you have found as a patch file right next to the
APKBUILD of your new kernel package. Mailing list posts are usually in the format of a patch file and can be used directly, while commits or pull requests (PRs) on GitHub can be downloaded as patch when you append
.patch to the URL (e.g. commit, patch).
If what you found on the web can't be used as patch file directly (e.g. sometimes the files are in other folders), but you understood how you would need to patch the source (from the search results or simply because you already knew), please follow this guide.
Patch files can contain arbitrary text before the first line with
--- in the file. Please use this space to link to the source where you found a patch (in case it is from the Internet) and to paste the error message, that your patch fixes (so it is easier to find for other people).
After creating the patch file and adding the source URL and error message, put the file name into
source in your
APKBUILD and give it another shot.
$ nano aports/device/testing/linux-wiki-example/03_description-here.patch $ nano aports/device/testing/linux-wiki-example/APKBUILD $ pmbootstrap checksum linux-wiki-example $ pmbootstrap build linux-wiki-example
We can't promise anything, but you shouldn't need to do this more than 2 times or so, before the kernel build finally goes through.
If you can't make your kernel compile or boot with the latest GCC from Alpine, you can also try to use GCC6 instead.
As GCC4 was recently introduced in postmarketOS repos, you can follow the procedure for GCC6 above and replace all gcc6 occurrences with gcc4 and add gcc4 (armv7/armhf/...)-gcc4 to your list of dependencies.
To use Clang as compiler you have to do the following in kernel package's APKBUILD:
- Add these lines:
Device specific package
deviceinfo file in an editor (replace
$ nano aports/device/testing/device-wiki-example/deviceinfo
If your device uses UFS storage, you may need to configure the rootfs image sector size. It defaults to 512b, but some devices use 4096b. In TWRP, check your sector size through the terminal:
$ fdisk -l /dev/block/sd* | grep -i "sector size"
If the sector sizes are 4096 bytes, add the following line to the
You can read more about sector sizes on this pull request thread.
In case you were asked for
boot.img analyzing, and skipped that section during init: You can run
pmbootstrap bootimg_analyze path/to/boot.img to get the right values for the
deviceinfo_flash_offset_ lines now. Filling out manually also works, but that is error-prone and therefore not recommended.
Create checksums and build the device package once to make sure it doesn't contain errors at this point (we didn't do that earlier, because
pmbootstrap would have complained about the invalid
pkgver of the kernel package):
$ pmbootstrap checksum device-wiki-example $ pmbootstrap build device-wiki-example
We are happy to help you!
If you get stuck, we are happy to help you in the chat and in the issues tracker. When asking for help, always include the APKBUILD you have written, and any custom patches you have applied, as well as the error message you have gotten from
This is a wiki, so please adjust everything that isn't detailed enough or would have helped you with porting.
If you have made some progress with a new port, please create a Device page to document your findings. Even if you didn't get very far and the kernel does not compile, this will help others to continue your work. To create a device page, you will need to register an account on this wiki. (You do not need to provide an e-mail address.)
To install to the system partition of an image file, run the following:
$ pmbootstrap install
If you want to install to a SD card, insert it into your PC and run the following. Replace mmcblk0 with the actual device name (
lsblk is handy to find out the correct device name). You don't need to format or partition it beforehand,
pmbootstrap will take care of that.
$ pmbootstrap install --sdcard=/dev/mmcblk0
Before you can run any flash command, you must put your device in the flashing/bootloader mode. It is usually done holding Volume Down & Power simultaneously when the device is switched off but it may vary depending on the device. For more information see the specific page for your device in the LineageOS Wiki.
If you want to install to the system partition, run the following (not for the SD card installation!):
$ pmbootstrap flasher flash_rootfs
In case your system partition is too small for the generated image (e.g. because you chose Plasma Mobile as UI), it is possible to flash to another partition as well. Just be sure to erase any previous installations of postmarketOS in other partitions, because the init script will start with the first one that it encounters. (To delete a previous version either use
dd or simply install the known working OS, e.g. Android, on it). Using multiple partitions with LVM is planned (#60).
$ pmbootstrap flasher flash_rootfs --partition userdata
If you have a device, that works with fastboot, you can boot the kernel now without flashing it:
$ pmbootstrap flasher boot
Otherwise, you will need to flash the kernel to the device boot partition:
$ pmbootstrap flasher flash_kernel
Alternatives to regular flashing
If the flashing method does not work, it is also possible to export all generated image files to a specific directory (with symlinks), so you can flash it manually with your host Linux system (or even on Windows with proprietary flashers such as Odin, if this is the only way it works for you):
$ pmbootstrap export $ pmbootstrap export --odin
For Android based devices, you can do a recovery zip installation.
If you are lucky, your screen may give some clues that you are booted into pmOS. If not, do not get discouraged, the graphics on your device may not yet be setup correctly. The next steps are to see if you can connect to the device through SSH over USB (or if that fails, via telnet). See the Boot process and Inspecting the initramfs pages for more details.
It is quite easy to give your phone Internet access via USB, when your PC is connected to the Internet.
In case it looks like your device did not even boot, have a look at Troubleshooting:boot.
As soon as USB networking is functional, or you have another indication that booting the device works successfully, it is time to upstream your work into the official pmaports repository. This way other people can benefit from your work, and build upon it.
See the git workflow article for detailed instructions.
Changing your installation
Install packages over SSH
$ apk add hello-world
You can also host packages you have built yourself from your PC. Just make sure to increase the package version when you build your own version of a package, that already exists. Otherwise the package manager can not know that your package is the newest one and should be installed. Check the output of
apk to see whether it is really installing the package or not.
Building a new system image
Whenever you rebuild a package (or pick a new one to be installed by default in
pmbootstrap init), you need to make sure that the package is actually installed in the chroot from which the system image gets generated. Achieve that by running
pmbootstrap install again, it should update all outdated packages. Pay attention to the output of
pmbootstrap log to see if it actually has been updated.
If something did not work as expected, you can always
pmbootstrap zap your chroots to start over with a clean installation.
A simple way to recompile your kernel (e.g. because you want to change your kernel config) and flash it to your device is running the following commands:
$ pmbootstrap build --force linux-wiki-example $ pmbootstrap install $ pmbootstrap flasher flash_kernel
The last flash_kernel step is only needed if your device has the kernel stored on an extra boot partition. Android/fastboot compatible devices have such a partition, and Maemo/MeeGo Nokia devices (N900, etc.) typically don't use it. If your device does not have a boot partition, update your system partition or SD card.
After you've gotten more familiar with postmarketOS, you could try out the
postmarketos-update-kernel as well. It allows you to flash a new kernel to the device's
boot partition (not to be confused with postmarketOS' own boot subpartition
Full disk encryption: osk-sdl support
If the display and the touchscreen interface are working, then it's time to add support for
osk-sdl, so that you are able to use full disk encryption on the root filesystem. Instructions for adding support can be found here: Porting osk-sdl to New Devices