MNT Reform 2 - Run Sculpt OS

June 3 2021 by Stefan Kalkowski

It has been a while since I started to do the first steps of porting Genode to the MNT Reform 2.

Since then the biggest hurdle was to enable the graphical subsystem and display. Unfortunately, the port of the i.MX 8MQ graphical subsystem available in Genode was based on a vendor fork of the Linux kernel 4.14. In contrast the MNT Reform 2 reference kernel is a recent vanilla Linux kernel 5.11 with some additional patches especially to the graphical subsystem. Hardware parts present in the MNT Reform 2, like the eDP to MIPI bridge that is used to connect the panel, were not present in the old vendor kernel at all. To make a long story short, backporting the new features in a reasonable time failed. But as a positive outcome the whole experience encouraged me in rethinking the way we port Linux kernel drivers to Genode, see the posts Breaking new ground and Generate dummy function definitions.

Before continuing the description and results of this new porting approach in more detail, I want to share with you the state of using Genode respectively running Sculpt on the MNT Reform 2.

Download and boot Sculpt OS

If you want to test out this yet unofficial release of the Sculpt OS for the MNT Reform 2, you can download a pre-built SD-card image from here:

You can copy the image on a fresh SD-card by using dd. Assuming your SD-card is named /dev/mmcblk0 when connected to your Linux host machine, then do:

 sudo dd if=sculpt-mnt-reform2-21.05.img of=/dev/mmcblk0 conv=fsync

Building a Sculpt image from scratch

Analoque to the Pinephone and A64 development work described by Norman Feske in his article series, I have decided to collect all work related to the MNT Reform 2 and its i.MX 8MQ SoC foundation in a dedicated repository:

It is based on the recently released Genode 21.05 and a few additional commits. To give it a try, you need to checkout Genode first:

 git clone https://github.com/genodelabs/genode.git genode
 cd genode
 git checkout 336350fe603fde4deb793f03d64fa31a99a5acf7 -b mnt_reform2_sculpt

Then you need to add the dedicated repository, which contains additional driver ingredients for the MNT Reform 2:

 git clone https://github.com/skalk/genode-imx.git repos/imx

Of course, you will need the Genode toolchain 21.05, either you install it into your development environment, see the toolchain download page, or you take the Docker container available, see article Genode development container for more details.

Before, you can build Sculpt, you have to download all 3rd party sources needed first:

 tool/ports/prepare_port bash coreutils curl dde_linux dde_rump e2fsprogs-lib gnupg jitterentropy libarchive libc libgcrypt libpng libssh mnt_reform2_linux mnt_reform2_uboot ncurses openssl stb ttf-bitstream-vera vim xz zlib

Now, you can create the necessary depot packages:

 tool/depot/create genodelabs/pkg/arm_v8a/sculpt-mnt_reform2 genodelabs/bin/arm_v8a/base-hw-mnt_reform2 CROSS_DEV_PREFIX=/usr/local/genode/tool/21.05/bin/genode-aarch64- UPDATE_VERSIONS=1 -j8

To finally create the system's image, we need a build directory first:

 tool/create_builddir arm_v8a

and add the new imx repository to the REPOSITORIES variable in build/arm_v8a/etc/build.conf, but ensure that it is the very first assignment to this variable, e.g. by putting it at the second line:

 REPOSITORIES += $(GENODE_DIR)/repos/imx

Moreover, you have to enable the following repositories that are commented out by default:

 REPOSITORIES += $(GENODE_DIR)/repos/libports
 REPOSITORIES += $(GENODE_DIR)/repos/ports
 REPOSITORIES += $(GENODE_DIR)/repos/dde_linux
 REPOSITORIES += $(GENODE_DIR)/repos/dde_rump
 REPOSITORIES += $(GENODE_DIR)/repos/gems

By adding:

 BOARD_RUN_OPT(mnt_reform2) := --include image/mnt_reform2

you include a run-tool plugin to produce a ready-to-boot SD-card image for the MNT Reform 2 including the bootloader, Sculpt system image, and GPT partition scheme. Then finally, you build this image via:

 cd build/arm_v8a
 make run/sculpt KERNEL=hw BOARD=mnt_reform2

The resulting image is located at var/run/sculpt.img, and can be written to an SD-card, like described at the beginning of this post.

Outlook

So far there are no pre-built, official packages available for this unofficial MNT Reform 2 release of Sculpt OS. Of course, you can build your own ones and deploy them. Moreover, the SD-card driver and Ethernet driver are not production ready yet. I like to rework them soon to be stable and more performant. Also, the framebuffer driver is still hardcoded to use the laptop's panel, but won't drive a monitor connected via HDMI. This will be changed soon too.

Edit (2021-09-29): updated to repository renaming of genode-imx.git