HW video offload on Fedora Arm

There’s been the starting pieces of hardware video offload with the stateless engine support for some time and it now supports at least H264/HEVC/VP8/VP9/mepg2 decode offload depending on the hardware capabilities. The problem has been support for software/userspace has taken longer then the initial drivers but now that’s catching up now with gstreamer support landing in 2020 and with apps like clapper now using it. I’ve been meaning to play with this and work out how to make it work in Fedora as it’s useful for devices based on the AllWinner/Rockchip/NXP i.MX8 devices like the Pine64 laptops/phones plus a bunch of other devices, even NVIDIA Jetson devices should work before long.

You’ll need to ensure you have gstreamer1-plugins-bad-free installed and the video application I was testing with is clapper:

$ sudo dnf install -y gstreamer1-plugins-bad-free clapper

Seeing what hardware offload is supported:

$ gst-inspect-1.0 v4l2codecs
Plugin Details:
  Name                     v4l2codecs
  Description              V4L2 CODEC Accelerators plugin
  Filename                 /usr/lib64/gstreamer-1.0/libgstv4l2codecs.so
  Version                  1.20.0
  License                  LGPL
  Source module            gst-plugins-bad
  Source release date      2022-02-03
  Binary package           Fedora GStreamer-plugins-bad package
  Origin URL               http://download.fedoraproject.org

  v4l2slh264dec: V4L2 Stateless H.264 Video Decoder
  v4l2slmpeg2dec: V4L2 Stateless Mpeg2 Video Decoder
  v4l2slvp8alphadecodebin: VP8 Alpha Decoder
  v4l2slvp8dec: V4L2 Stateless VP8 Video Decoder
  v4l2slvp9alphadecodebin: VP9 Alpha Decoder
  v4l2slvp9dec: V4L2 Stateless VP9 Video Decoder

  6 features:
  +-- 6 elements

Finally in Clapper you need to enable playbin3 option, I also enabled Pipewire audio support:
Clapper Preferences

We will also be enabling decode support in Chromium and Chromium freeworld before long, there’s a little more work to do here, but as usual once it lands it’ll all just start to work in Chromium too!

Short history of ARMv7/armhfp/arm32 in Fedora

Back in mid November I proposed a change for Fedora 37 to retire ARMv7 as an architecture, FESCo accepted the proposal. Per the Fedora 36 schedule we branched Fedora 36 this week. Last night I enacted the last of the process to disable it in rawhide so to quote “It’s dead Jim”. The last release of Fedora to support ARMv7 AKA armhfp AKA arm32 will be Fedora 36 which will go end of life around June 2023.

I thought I’d cover a few of the things we achieved with Fedora ARM and some of the impact it’s had on the wider Linux on ARM ecosystem which people may not have realised.

First a little bit of ARM history in the Fedora ecosystem. The beginnings of ARM support actually precedes Fedora all the way back to 1998 with a fork of Red Hat Linux 4.2 and more officially with Red Hat Linux 5.1 on the Corel Netwinder (I always wanted one of those but they weren’t available in Aus).

In Fedora itself the earliest details I remember was that Marvell bootstrapped ARMv5 in Fedora 7 and continued to build and support it through to Fedora 12. This “software architecture” was known as softfp. It was optimised for the ARMv5 architecture which didn’t have a hard requirement on a floating point unit so emulated it when it was needed hence “software floating point”. In Fedora 13 Seneca College took over the ARMv5 infrastructure and building from Marvell. I officially got involved in the Fedora 14 build process and soon after was also contracted by OLPC to drive Fedora on OLPC for their ARM based XO laptops as well as work on their i686 devices to have a single OS for all of them.

In mid 2011, the Fedora 15 timeframe, a small Red Hat team started to do a ARMv7 hard floating point, AKA hardfp or armhfp, bootstrap as ARM’s new v7 mandated a floating point unit. The bootstrap included the core toolchain (binutils/gcc/glibc/elfutils and friends) and ultimately the entire distribution, I drove this effort from a community, build and packaging perspective. This required 100s of patches to upstream projects that made many assumptions about ARM only being softfp, but it also allowed us at the time to fix many general architecture assumptions in these projects. The hard floating point bootstrapping was useful for the wider community too, it was used by Nokia as the base of it’s hardfp efforts for Maemo, plus other distros used it as as it’s much easier/quicker if you already have a full distro running the architecture you wish to boostrap. What wasn’t generally known at the time was also the first new architecture that has been bootstrapped in the Fedora/RHEL ecosystem since x86_64 a long time before and it allowed Red Hat to refresh it’s memory on how to do this in preparation of the then unannounced aarch64 architecture and the POWER Little Endian intentions, basically it provided a cover story. We also worked to get other languages such as Fortran, golang, rust and others building and working on armhfp and those other architectures. The final piece of this was ARMv7 being promoted to a primary Fedora architecture in Fedora 20. This then later went on to my proposal to redefine secondary architectures in Fedora.

In the wider community of Linux Fedora ARM was the first distribution to adopt the kernel “multi platform” work enabling us to go from building 5 different kernels to support a handful of arm devices to a single kernel supporting 100s of devices in a very short period of time. I worked with closely Arnd Bergmann from Linaro on issues with the early pieces of the multiplatform work. In upstream U-Boot we posted the first distro_boot patches to support booting Linux in the same way across all the devices we actively supported so we didn’t need specially wrapped kernels and know exact offsets for every SoC or device. The distro_boot support evolved, working with SUSE, into UEFI support in U-Boot further standardising the ARM boot process by abstracting the pieces that were different and letting the firmware deal with them. This work ultimately evolved into EBBR and the ARM System Ready IR spec. In Fedora 34 we moved to soley supporting UEFI on both ARM architectures. A lot of Linux distros still have specific kernels for each device and use non standard boot methods for devices and hence have an image for each device/use-case they wish to use. This was something Fedora identified very early on as something that would not scale!

Fedora also leads a lot of things in the gcc toolchain stack across all our supported architectures, we’ve actively enabled a lot of security features and other things like LTO early on. As the Fedora gcc maintainers, employed by Red Hat, are also key upstream GCC maintainers we’re almost always the first distribution to rebase onto a new release before it’s a stable release, for example Fedora 36 had just had a mass rebuild against a gcc-12 pre release snapshot. This builds all of the 50k or more source packages with the pre-release of the new toolchain making for a much better release for the wider GCC community because this picks up a number of bugs/regressions in both the general support but also in the architectures Fedora supports which means the ARMv7 hardfp support in GCC has benefited from 100s of bugs we’ve detected in gcc/binutils/glibc etc before they land in a stable gcc release. With the retirement of ARMv7 in Fedora this is going to be something the wider ARMv7 community is going to have to pick up post the GCC-12 release.

Over the subsequent 11 years of ARMv7 support in Fedora, and much longer if you include the early ARMv5 the distribution has also enabled a number of other innovative features like support for containers, support for devices like the Raspberry Pi 2 and 3 in Fedora 25. as mentioned various toolchains, and fun things like robots. Of course we also lose some things too. Devices like the BeagleBone don’t yet have a 64 bit sibling, but there’s less and less 32 bit devices coming out and the use of armhfp is waning quickly and the maintenance cost is rising as the industry moves more generally to 64 bit even in embedded use cases and the fact is with devices like the $15 Raspberry Pi Zero 2W it makes less and less sense even if I do still actively run BeagleBones, a Panda-ES and 3 different i.MX6 devices.

So I engaged with the wider Arm ecosystem and it made sense to finally sunset our ARMv7 32 bit support. We’re of course leaving it in good shape with things like gcc-12, the latest rust and golang toolchains and 5.17 kernels, much newer by the time F-36 goes EOL in June 2023, it will be in good shape if people wish to use it as the basis of some form of continuing ARMv7 supported Linux distribution.

Sail off into the sunset friend, it’s been a fun 12 years of hacking on those projects!

Documenting my various arm and IoT devices: quick overview

It’s been around ten years since I got my first arm single board computer, a Beagle-xM, which started me down the route of playing with Fedora on ARM and ultimately to my role in device edge/IoT at Red Hat. Shortly after that time I also moved into my current flat, almost ten years later I finally made the decision to move to a new place.

In the process of unpacking the contents of boxes from the flat into my new home office I thought I would document all my devices. This is mostly for my own reference, but I have little doubt others are interested from previous conversations. I’ve broken the list down into a few broad categories, mostly so the blog post isn’t unwieldy, there’s certainly cross overs between the categories, like some generations of the Raspberry Pi can run in either 32 or 64 bit mode, some Arm SBCs also have an integrated micro controller etc. For simplicity I’m putting those cross over devices in a single list, that of which they’re most capable, I’m also not putting devices on the list that aren’t easily able to run an open source OS such as Linux or Zephyr RTOS as I have numerous micro controllers/phones etc I can’t be bothered with and hence they’re not seen as useful for this list.

The lists, I will update with links as I post them, are going to be as follows:

  • Part one: Arm 64 bit devices (aarch64)
  • Part two: Arm 32 bit devices (ARMv7)
  • Part three: Micro controllers
  • Part four: x86 and other devices

Three ways to speed up dnf on arm devices

I have a large bunch of Arm Single Board Computers I use for testing a lot. Most of the testing ends up being pretty basic stuff like firmware, kernels, and the various bits of hardware peripherals that people use like storage, network, display and sound output, plus things like sensors and HAT support.

The problem is that these devices often aren’t the fastest in the world for various reasons so I want to be able to apply updates to the basic system as quickly as possible to find out the results. Over time I’ve worked out that these three things speed up dnf quite a bit for the sort of testing I wish to do are as follows:

  1. Disable modularity:
    sed -i 's/enabled=1/enabled=0/' /etc/yum.repos.d/fe*mod*
  2. Don’t install weak dependencies:
    echo "install_weak_deps=False" >> /etc/dnf/dnf.conf
  3. Disable dnf makecache. It never seems to be up to date when you need it anyway:
    systemctl disable dnf-makecache; systemctl mask dnf-makecache

You may need to re-do some of these each major update as they seem to want to force you to have them every time.

Fedora package spring cleaning

So it’s meteorological spring, at least in the Northern Hemisphere, and I’m preparing to move house for the first time in almost a decade so of course it’s time to procrastinate and have a spring clean of the packages I maintain!

A number of these I’ve maintained longer than I’ve been in my current flat and like a lot of the contents of my flat I’m not sure why I still have them! A bunch of them I packaged when MeeGo was the coolest thing to run on your Netbook and before GNOME-3 was stable and packaged and I wanted to run MeeGo on Fedora on my ASUS EeePC 901! Then a bunch I’ve acquired over the years because various things I was interested in depended on them. There’s others I actually have no idea why I own them! Anyway, with my day job doing “Device Edge” or “IoT” and with less spare non work time (why yes, apparently I do have a life outside of Fedora, who knew!) I decided it’s high time I relinquished the maintainership of these packages and let someone else love them or allow them to sail off into the sunset of their, probably long overdue, retirement!

So without further ado the list of packages I relinquishing is as follows…. Please reply to the list message or message me on IRC/email (if you know the Fedora packaging process) to (co)maintain something in this list:

* GNOME related:
clutter
clutter-gtk
clutter-gst
cogl
libchamplain
rest

* A UPnP stack, used (or at least used to be) by GNOME and others:
gssdp
gupnp
gupnp-av
gupnp-tools
gupnp-dlna
gupnp-igd
rygel

* Ancient gnome related (please retire or move the deps to copr already):
gamin
libglade2
libgnomecanvas
gnome-themes
ORBit2

* GTK VoIP client. Mostly dead upstream. Has explicit deps/tightly coupled with opal/ptlib:
ekiga
opal
ptlib

* iOS/iMobiledevice - Apple iDevice support:
ifuse
libplist
libusbmuxd
libimobiledevice
usbmuxd

* Random / no idea TBH:
libfakekey (kde-connect-libs)
icon-slicer
telepathy-mission-control
loudmouth

A list of packages that I still have an interest in but would appreciate a co-maintainer:
dotconf
festival-freebsoft-utils
speech-dispatcher
flite
csound

Zephyr RTOS 2.x on Fedora: Configure the build environment

It’s been a while since I’ve had time to play with the Zephyr RTOS project and the project has evolved greatly since so I thought I’d document the process I went through while playing with Zephyr 2.1 on Fedora using the Fedora native cross toolchains rather than the various ones suggested by the Zephyr Project docs.

I’m going to do a couple of posts in this series to break it up a little. This first one will be getting a generic build environment setup. I’ll go into more detail on the specific devices I’m playing with but the ones I have handy are ARM Cortex-M based so that’s what I’ll be focusing on even though Zephyr RTOS supports numerous architectures.

As before it’s worth reading the latest Zephyr Getting Started guide. This time around I’m using a AWS aarch64 a1.medium instance running a Fedora 31 cloud instance but I’ve also tested that a DigitalOcean Droplet with 2Gb RAM works with the later ZephyrRTOS releases too.

Once you have a Fedora instance up and running install the required dependencies:

# disable modularity, mostly just slows things down.
$ sudo sed -i 's/enabled=1/enabled=0/' /etc/yum.repos.d/fe*mod*

# install core utils, git and cross compilers
$ sudo dnf install git-core cmake ninja-build gperf dfu-util dtc \
xz file python3-pyelftools arm-none-eabi-gcc-cs python3-pip

# requirements for the west (Zephyr meta build tool)
$ sudo dnf install python3-colorama python3-configobj \
python3-configobj python3-docopt python3-pykwalify \
python3-dateutil python3-colorama python3-docopt \
python3-pykwalify python3-packaging

We now install west:

$ pip3 install --user --upgrade west

We now have key build dependencies installed so we can initialise west and clone key repos using west (this will take a little while to do an initial clone run):

$ west init zephyr
$ cd zephyr
$ west update

Setup the Zephyr environment for cross compiling with the distribution tools:

$ export ZEPHYR_TOOLCHAIN_VARIANT=cross-compile
$ export CROSS_COMPILE=/usr/bin/arm-none-eabi-
$ source zephyr-env.sh
$ mkdir builds

By default the above uses the git master branch of the Zephyr git repo. If you wish to use a stable branch you can just check it out. The latest stable release is, currently, 2.1 so to use this you can check out the stable branch:

$ git checkout v2.1-branch

With this we now have a Zephyr RTOS development environment setup for building for Arm Cortex-M based devices on Fedora using the distribution’s cross toolchains.

The state of open source GPU drivers on Arm in 2019

I first blogged about the state of open source drivers for Arm GPUs 7 years ago, in January 2012, and then again in September 2017. I’ve had a few requests since then to provide an update but I’ve not bothered because there’s really been no real change in the last few years, that is until now!

The good news

So the big positive change is that there’s two new open drivers om the scene with the panfrost and lima drivers. Panfrost is a reverse engineered driver for the newer Midguard and Bitfrost series of Mali GPUs designed/licensed by Arm, whereas Lima is aimed at the older Utguard series Mali 4xx series of devices. Panfrost, started by Alyssa Rosenzweig, and now has quite a large contributor base, has over the last few months has been coming along leaps and bounds and by the time Mesa 19.2 is out I suspect it should be able to run gnome-shell on an initial set of devices. I’m less certain the state of Lima. The drivers landed in the kernel in the 5.2 development cycle, which Linus just released. On the userspace side they landed in the mesa 19.1 development cycle, but they’ve greatly improving in mesa 19.2 cycle. Of course they’re all enabled in Fedora rawhide, although I don’t expect them to be really testable until later in the 19.2 cycle, but it makes it easy for early adopters who know they’re doing to be able to start to play.

A decent open source driver for the MALI GPUs from Arm had been the last biggest hold out from the Arm ecosystem we’ve been waiting for and it covers a lot of the cheaper end of the SBC market with a lot of AllWinner and some Rockchip SoCs having the MALI 4xx series of hardware, which will use the Lima driver and other lower to midrange hardware shipping with the newer Mali midguard GPUs like in the Rockchip 3399 SoC.

Other general updates

Since I last wrote the freedreno (QCom Ardreno) and etnaviv (Vivante GCxxx series) have continued to improve and add support for newer hardware. The vc4 open drivers for the Raspberry Pi 0-3 generations have seen gradual improvement over time, and there’s a new open v3d driver for the Raspberry Pi 4 which they use from the outset.

The last driver is one that seems to have transitioned to be in limbo is the driver for the Nvidia Tegra Arm platform. While it has an open driver for the display controller, and the GPU mostly works with the nouveau driver, at least on the 32 bit TegraK1 (the upstream state of the Tegra X-series is definitely for another post) they appear to have yet another driver, not their closer x86 driver, but another one (not the latest rev, which is 4.9 based, but the only linkable version I could find) which is needed to do anything fun from an CUDA/AI/ML point of view, I wonder how it will fit with their commitment to support Arm64 for their HPC stack or will that only be interesting to them for PCIe/fabric attached discrete cards for HPC super computer deals?

That brings me to OpenCL and Vulkan for all the drivers above, for the vast majority of the open drivers support for either is basically non existent or in the very early stages of development so for the time being I’m going to leave that for another follow up in this long winded series, probably when there’s something of note to report. The other thing that is looking quite good, but one for another post, is video acceleration offload, there’s been quite a bit of recent movement there too.

Raspberry Pi improvements in Fedora 29

So Fedora 29 is probably going to account for the largest single improvement to support on the Raspberry Pi support in Fedora since we added initial support in Fedora 25. It certainly wasn’t without issue, but after quite a bit of debug we’ve got the post release issues with the WiFi back to being stable!

WiFi improvements
The support for upstream NVRAM files and the ability to add those files to linux-firmware means we get WiFi support for the Raspberry Pi 3 Series of devices out of the box! No need to grab anything, it just works! Well mostly, we had some issues with WiFi being very intermittent, as well as a missed bug around aarch64 but now with the 4.19.10 kernel everything appears to be working and stable. This makes me very happy and it took longer than I had hoped but we’re there. This device specific NVRAM driver support will also help another bunch of cheap Arm and x86 based devices that ship with Broadcom/Cyprus based WiFi support moving forward.

ZRAM enabled by default
By supporting and enabling ZRAM swap by default we get a more responsive device and less wear on the MicroSD storage. Over all we’ve seen reasonable performance improvements and to no date no major issues.

GNOME performance improvements
In May 2018 the Raspberry Pi Foundation kindly hosted a GNOME Performance Hackfest in the lovely Cambridge. Over a couple of days we managed to fix a number of issues seen, review and document a number of issues and work on a number of ways of reducing the memory usage of GNOME. Of course this improvement is primarily seen constrained devices like the Raspberry Pi but ultimately less memory utilisation by GNOME even helps devices with decent amounts of RAM and CPUs too. The fixes didn’t arrive in time for Fedora 28, but a bunch have landed in Fedora 29 providing noticeable improvements, and the GNOME team is by no means done and there will be more coming in Fedora 30 and beyond! It was an excellent start and I expect there will be ongoing enhancements here into the future especially with devices like the Purism Phone which will have similar constraints.

Initial CPU frequency support
Another of the largest issues around the Raspberry Pi is complaints it was slow, part of the issue here is that there’s no upstream CPU Frequency driver which means all models of the Raspberry Pi run at a glacial, but safe, 600Mhz out of the box compared to the highest speed, which on the 3B+ is 1400Mhz. With Fedora 29 we’ve landed an experimental cpufreq driver which allows us to run the Raspberry Pi 3-Series at much closer to optimal speeds. While this is experimental it might not stay around if we find out it causes issues or ends up being a maintenance burden but to date it hasn’t yet appeared to have caused any issues.

HWmon Voltage Sensor
There’s a new driver that reports when the voltage supplied by the PSU drops below the required voltage. It can be a bit noisy in dmesg but one of the biggest support problems we have with the Raspberry Pis is people using a power supply that’s not powerful enough, this issue is more of a problem with Fedora 29 because with the support for running at faster frequencies due to the cpufreq driver it means we also draw more power and some PSUs that were previously fine now cause issues because they can’t supply enough current.

Enhanced support for config.txt
A lot of the hardware addons are supported in Raspbian are done by enabling things in the config.txt file, this in turn does things like loading DT overlays and merging them with the base DT to enable extra hardware like HAT support. We have enhanced the way Fedora works with this which enables us to be much closer to the way Raspbian handles these things. The advantage this has is that the documentation that’s written for Raspbian is then usable by Fedora in the wider Raspberry Pi ecosystem which in turn makes it easier for end users to get HW up and running due to less differences in process. There’s further enhancements to make here but every step closer is easier for everyone to enable and use their favourite HATs.

Improved bcm283x firmware support
In preparation for grub2 support we enhanced how we deal with the firmware that the Raspberry Pi uses for booting. This deals with the early startup. We never use to upgrade it by default to ensure things didn’t break, but it also meant most users also didn’t by default get the fixes and enhancements. Now we do. The config.txt is also handled directly which means if you never edit the file you now automatically get any changes we make, because rpm handles the file as a config file, if we change it you get a .rpmnew file so you won’t lose your changes.

Camera support
This wasn’t available in the Fedora 29 4.18 kernels, but with the rebase to the 4.19 kernel the support for the camera on the Raspberry Pi CSI Camera interface improved enough we could enable this in Fedora. The early 4.19 kernels don’t automatically detect and load support if the camera module is attached. There’s some patches in 4.20 in rawhide for this, and we’ll bring some of this to 4.19 soon, and we’re working with upstream to further improve the camera support. You’ll also want the latest bcm283x firmware which tweaks some of the config.txt and updates to a firmware with ISP fixes.

Another improvements
There was also a number of general Arm improvements which sped up crypto on the Raspberry Pi, improved the USB, fixed up some issues with the wired ethernet on the 3B+, power and a number of other fixes. As always there’s more coming. The 4.20 kernel rebase should also bring with it analog sound support early in the new year.

Conclusion
Overall I was pleased with the work that landed in Fedora over 2018 for the Raspberry Pi. The WiFi regression was disappointing, but now with that fixed in 4.19.10 we have WiFi support out of the box without users needing to download anything which moving forward will make things a lot more straight forward. The initial support for the camera makes it much more useful in numerous use cases and we’ll really polish up the HAT support in Fedora 30 which for me is the last remaining big ticket item for Raspberry Pi support. There’s still some annoying bits around the EDID detection in the display, but there’s work to improve that upstream, and also there’s work to land the media decode offloading upstream too which will also one of the few remaining bits.

Using ZRAM as swap on Fedora

One of the changes I did for Fedora 29 adding using ZRAM as swap on ARM. The use of compressed RAM for swap on constrained single board computer devices has performance advantages because the RAM is an order of faster than most of the attached storage and in the case of SD/emmc and related flash storage it also saves on the wear and tear of the flash there extending the life of the storage device.

The use of ZRAM as swap isn’t limited to constrained SBCs though, I also use it on my x86 laptop to great effect. It’s also very simple to setup.

# dnf install zram
# systemctl enable zram-swap.service
# reboot

And that’s it! Simple right? To see how it’s being used there are three commands that are useful:

# systemctl status zram-swap.service
‚óŹ zram-swap.service - Enable compressed swap in memory using zram
   Loaded: loaded (/usr/lib/systemd/system/zram-swap.service; enabled; vendor preset: disabled)
   Active: active (exited) since Tue 2018-10-09 22:13:24 BST; 3 days ago
 Main PID: 1177 (code=exited, status=0/SUCCESS)
    Tasks: 0 (limit: 4915)
   Memory: 0B
   CGroup: /system.slice/zram-swap.service

Oct 09 22:13:24 localhost zramstart[1177]: Setting up swapspace version 1, size = 7.4 GiB (7960997888 bytes)
Oct 09 22:13:24 localhost zramstart[1177]: no label, UUID=d79b7cf6-41e7-4065-90a9-000811c654b4
Oct 09 22:13:24 localhost zramstart[1177]: Activated ZRAM swap device of 7961 MB
Oct 09 22:13:24 localhost systemd[1]: Started Enable compressed swap in memory using zram.
# swapon
NAME       TYPE      SIZE   USED PRIO
/dev/zram0 partition 7.4G 851.8M   -2
# zramctl
NAME       ALGORITHM DISKSIZE   DATA  COMPR  TOTAL STREAMS MOUNTPOINT
/dev/zram0 lz4           7.4G 848.3M 378.4M 389.9M       8 [SWAP]
#

When I was researching the use of ZRAM there was a lot of information online. A lot of implementations sliced up the zram into multiple slices to enable the balancing of the slices across CPUs, but this is outdated information as the zram support in recent kernels is now multi threaded so there’s no performance advantage to having multiple smaller swap devices any longer, and having a single larger swap space allows the kernel to be more effective in using it.

In Fedora all the pieces of the Fedora implementation are stored in the package source repo. So those that are interested in using zram for other use cases are free to test it. Bugs and RFEs can be reported as issues in pagure or in RHBZ like any other package.

Fedora on the UDOO Neo

Some time ago I backed the UDOO Neo Kickstarter as it looked like a nifty, well featured, IoT device. I got the full option which came with 1Gb RAM and both wired and wireless Ethernet and some add-on sensors. It was a well run kickstarter campaign and the device was well packaged with a fab box. It has both a Cortex-A9 processor to run Fedora and a Cortex-M4 embedded processor to enable you to do Arduino style functionality which should be interesting to experiment with.

For various reasons it has sat around gathering dust, it’s been a bit of a long drawn out process with me randomly poking it as time allowed.. Primarily this was because there was no decent upstream U-Boot and kernel support, and I’d not had the time to hack that up myself from various downstream git repositories, but even without Fedora support their forked Ubuntu distro in the form of UDOObuntu has an experience that is truly terrible!

Late 2016 the problem of a lack of upstream support for U-Boot and kernel changed with initial basic support landing upstream for all three (Basic, Extended and Full) models so with a few cycles over a weekend it was time to dust it off to see if I could get Fedora 26 (did I mention this has been long running?) running on it and to see what worked.

The first thing for me to do was to setup a serial console for easy debugging. The UDOO Neo documentation is generally outstanding and the pins for the UART1 TTL are documented. Two things to note here is that the headers are female rather than the usual SBC male pins so I had to bodge my usual usb to serial TTL with some male-male jumper wires and you’ll need a ground for the TTL which is undocumented on their page, I used one of the GNDs as documented on connector J7 and all was good.

So after an initial set of fixes to the U-Boot support it saw my Fedora install and started to boot! Success! Well sort of, as mentioned above the initial support is rudimentary, it started to boot the kernel and very quickly managed to corrupt and destroy the filesystem not making it much beyond switch root. That wasn’t good. In the last week or two I’ve had a little time to look again, similar issues, it was better than it was a year or so ago but it still ended up with corruption. I reached out to one of the maintainers from NXP that deals with a bunch of the i.MX platforms and I got directed to a handful of patches, a test kernel and image later and a test boot… all the way to initial-setup! SUCCESS!

The core support for the i.MX6SX SoC and the UDOO Neo is pretty reasonable, with the MMC fixes it’s been very stable, all the core bits are working as expected, included wired and wireless network, thermal, cpufreq, crypto and it looks like the display should work fine. There’s a few quirks that I need to investigate further which should provide for a fun evening or weekend hacking. There has also been recently merged support for the i.MX6SX Cortex-M4 land upstream in Zephyr upstream for the 1.13 release, so getting that running and communication using Open-AMP between Fedora and Zephyr should also be an interesting addition. I think this will be a welcome addition to Fedora 29, and not a moment too soon!!