Changelog

v0.13.9 - 2025-09-18

• Changes

  • Document application config keys. These are now official. If you had been modifying the application config for regression tests, note that the :env key is now :fwup_env and :revert_fw_path is now ops_fw_path.

  • Add Nerves.Runtime.firmware_slots/0 to return a map indicating the currently running slot and the one that will be run on next boot. Please update any calls to get "nerves_fw_active" directly from Nerves.Runtime.KV since the new firmware_slots/0 is more accurate and handles more scenarios on Nerves devices.

  • Add firmware_validation_status/0 to allow callers to know whether the status is really unknown. This isn't possible with firmware_valid?/0 which is problematic since unknown could mean that the U-Boot environment is unreadable and a fix is needed. Instead firmware_valid?/0 returns true in that case since this could be an old Nerves device without validation.

  • Replace call to Busybox mount to determine filesystem read-only status with a module that reads /proc/self/mountinfo.

  • Expose mount information via Nerves.Runtime.MountInfo. If you had been using MountParser, please update your calls. MountParser was not intended to be public API (@moduledoc false) and was removed.

  • Serialize calls to fwup to reduce chance of accidental eMMC/MicroSD corruption

  • Bulletproof many functions to return errors if the :nerves_runtime application stops. This can happen when the device is not in a good state and raising in NervesRuntime KV and FwupOps functions made things worse. This should be a rare case.

v0.13.8 - 2025-03-24

This release has many updates, but none of them are expected to be noticeable to most Nerves users. Most are in support of the Raspberry Pi's TRYBOOT feature which is not supported in official Nerves systems.

• Changes
  • Update licensing and copyright for REUSE compliance
  • Add Nerves.Runtime.FwopOps.status/1 to report the currently running slot and the one that will run on the next boot
  • Improve active (current) firmware slot detection when ops.fw is available. While nothing has changed in official Nerves systems, more documentation has been added here to make the ops.fw tasks use official.
  • Support reloading KV cache and reload it automatically on firmware operations that may affect it.
  • Return error and warning details from fwup calls to avoid losing failure reasons
  • Reduce Dialyzer warnings when calling Nerves.Runtime.mix_target/0 at runtime

v0.13.7 - 2024-01-15

• Changes
  • Add Nerves.Runtime.Heart.guarded_immediate_reboot/0 to ungracefully reboot.
  • Modify Nerves.Runtime.FwupOps.factory_reset/1 to immediately reboot to avoid a graceful shutdown unintentionally partially undoing the factory reset work.
  • Default EXT4 application partitions to remount read-only when formatted. This changes the behavior from file I/O returning file system corruption errors to file I/O returning read-only filesystem errors. The change was made for consistency with F2FS and to lock things down as soon as corruption was detected.

v0.13.6 - 2023-11-10

• Changes
  • Fix errant return from Nerves.Runtime.reboot when using guarded reboots. This resulted in code running after the reboot call that wasn't expected to have been run.
  • Simplify and harden power off and reboot for edge cases

v0.13.5 - 2023-09-26

• Changes
  • Add Nerves.Runtime.FwupOps to make it easier to run commands from the revert.fw (older) and ops.fw (newer) files. The firmware revert logic had always used this, and this makes getting to factory reset and preventing reverts easier. Some operations aren't available on all Nerves systems.
  • Various documentation and syntactical updates instigated by Elixir 1.15.

v0.13.4 - 2023-04-24

• Changes
  • Fixed new compiler warnings with Elixir 1.15
  • Support the Nerves Heart v2.2 snooze feature. Nerves.Runtime.Heart.snooze/0 will request that heart continues to pet the hardware watchdog and ignore lack of updates from Erlang for a short amount of time to allow debug of conditions that would otherwise be interrupted by a watchdog timeout.
  • Report errors from Heart functions rather than hang forever when Erlang :heart is unresponsive.
  • Support additional status from Nerves Heart v2.2 to report the initial bootup grace period timeout and snooze timeout remaining.

v0.13.3 - 2022-11-25

• Changes
  • Fixed poweroff with Nerves Heart v2.0 (be sure to use Nerves Heart v2.0.2 as well). Thanks to @amclain for finding and fixing this.

v0.13.2 - 2022-11-22

Support Nerves Heart v2.0.0 attributes and features. Nerves Heart v2.0.0 is a major update that addresses rare cases where devices would fail to reboot or detect an issue. It also adds helpful statistics. See the docs for details. Nerves Heart v1.x versions are still supported.

• Changes
  • Support guarded reboot and poweroff if Nerves Heart 2.0 is available. Reboots and poweroffs still gracefully stop the VM, but they now don't require Busybox reboot or poweroff, and they stop petting the hardware watchdog to set a hard limit.
  • Support Nerves Heart initialization completion notifications. This lets you protect the time between boot and :heart.set_callback/1 should something happen that prevents the callback from being set. This addresses an issue where the VM would think everything is great since it wasn't calling the callback to find out that it was not.

v0.13.1 - 2022-07-06

• Changes
  • Handle another way key-value stores were being mocked pre-v0.13.0.
  • Fix default boardid_path in mix.exs

v0.13.0 - 2022-07-05

This update replaces Nerves.Runtime.target/0 with Nerves.Runtime.mix_target/0. It is not believed that the former function was used much, but if you do use it, note the return value change in mix_target/0.

• Changes
  • Support customizable key-value store backends so that it's possible to store firmware and board metadata outside of U-Boot environment blocks. See the :kv_backend configuration option.
  • Support changing the firmware revert script path (see :revert_fw_path)
  • Decide host vs. target differences at compile time to avoid target-only or host-only logic and dependencies existing unnecessarily at run-time.

v0.12.0 - 2022-06-03

This is a major update to nerves_runtime that removes SystemRegistry. SystemRegistry has been disabled by default for years, but it could be re-enabled if device insertion and removal events were needed. That functionality has been moved to nerves_uevent and updated to use the property_table library used by VintageNet.

Elixir 1.11 is the minimum supported Elixir version now.

To upgrade from prior versions of nerves_runtime:

1. If you're using :system_registry at all, please review the :nerves_uevent documentation for new library.
2. Remove config :nerves_runtime, :kernel, use_system_registry: false from your target.exs. It's not used any more.
3. If you had config :nerves_runtime, :kernel, autoload_modules: false in your target.exs, change it to config :nerves_uevent, autoload_modules: false.

• Bug fixes

  • Run reboot and poweroff sequences in their own Erlang process. This fixes a bug were the process that calls reboot gets killed partway through the reboot process and the system doesn't actually reboot.

• Changes

  • Kernel logging and syslog monitoring has been moved to nerves_logging. The functionality is the same as before, but it's now possible to use without nerves_runtime.
  • Added convenience routines for getting status from nerves_heart.

v0.11.10 - 2022-3-17

• Bug fixes
  • Update the initial device scan to be deterministic and to trigger events for containers before the devices they contain. This fixes a subtle issue that prevented RT5379 WiFi module drivers from automatically being loaded.
  • Batch up modprobe invocations

v0.11.9 - 2022-3-6

• Changes
  • Save shell history on first boot. Previously, Erlang would open up the shell history file before the data partition was formatted and wouldn't retry. Nerves.Runtime now resets shell history so that it retries.
  • Call modprobe to load kernel modules to C to reduce boot time.

v0.11.8 - 2021-10-25

• Changes
  • Update the mix dependencies to allow uboot_env v1.0.0 to be used.

v0.11.7

• Bug fixes
  • Nerves.Runtime.firmware_valid?/0 would return that the firmware wasn't validated when the validation feature wasn't in use. This was confusing since firmware is assumed valid when the feature is off.

v0.11.6

• New features

  • Added support for implementing auto-revert logic using U-Boot's bootcount/upgrade_available feature. This can simplify U-Boot scripts. See the README.md for details.

• Bug fixes

  • Specify "-f" to force f2fs filesystem formats like those of other filesystems. Thank to Eric Rauer for catching this oversight.

v0.11.5

• Updates
  • If /etc/sysctl.conf is present, run sysctl to load and set the kernel configuration parameters in it.
  • Improve C compilation messages and error help

v0.11.4

• Updates
  • Added Nerves.Runtime.firmware_valid?/0 to easily check whether the firmware has been marked valid for systems that auto-rollback.

v0.11.3

• Updates
  • Support uboot_env v0.3.0. This version of uboot_env has backwards incompatible changes, but they don't affect nerves_runtime, so the mix.exs deps spec allows it now.
  • Tightened up the specs on Nerves.Runtime.KV functions.

Support for OTP 20 was removed. uboot_env v0.3.0 requires OTP 21 and later. If you still are using OTP 20, lock the version of uboot_env to ~> 0.2.0 in your mix.exs.

v0.11.2

• New features
  • Added Nerves.Runtime.validate_firmware/0 for validating firmware on systems that auto-rollback. This only abstracts the setting of the nerves_fw_validated key. It doesn't add any new functionality. However, it will enable auto-rollback to be added to Nerves systems in a consistent manner in the future and allow for platform-specific variations without impacting application code.

v0.11.1

• Bug fixes
  • Reap zombie process that was created by the uevent port helper.
  • Support uboot_env v0.2.0 to reduce memory garbage that's created when reading and writing U-Boot environment blocks

v0.11.0

• New features
  • Add Nerves.Runtime.serial_number/0. It will call out to the underlying system to return the device's serial number however it's stored.
  • Add a fallback to haveged for systems that don't have hardware random number generators or otherwise can't use rngd.

v0.10.3

• Bug fixes
  • Fix potential process accumulation from the kmsg_tailer process ignoring stdin being closed on it.
  • Tightened deps to avoid combinations that would be difficult to support

v0.10.2

• Bug fixes

  • Fix off-by-one error when processing uevent messages with device paths longer than 16 segments. This also bumps the max number of segments to 32.
  • Fix logger message about rngd failing when it was successful
  • Log errors when required commands aren't available rather than raising. It turned out that raising was disabling logging and that was making it hard to figure out the root cause.

• Enhancements

  • Switch from parsing /proc/kmsg to /dev/kmsg for kernel messages. The device interface supplies a little more information and is unaffected by other programs reading from it. This change refactored syslog/kmsg parsing to improve test coverage. This is considered to be an internal API. If you were using it, you will need to update your code.

v0.10.1

• Bug fixes
  • Fix exception on init when mounting the application data partition. This addresses an issue where :nerves_runtime would exit due to an unmatched call to System.cmd/3.

v0.10.0

• New feature
  • Added Nerves.Runtime.KV.put and Nerves.Runtime.KV.put_active to support setting environment. This removes the need to run fw_setenv and also updates the cached key/value pairs. Thanks to Troels Brødsgaard for implementing.

v0.9.5

• Bug fixes
  • Fix C compiler error (PATH_MAX undeclared) on x86_64/muslc systems

v0.9.4

• Enhancements
  • Reduced number of syscalls needed for transferring device detection events (uevents) to Elixir by batching them
  • Improved start up performance by moving initial device enumeration to C
  • Handle uevent overloads by dropping messages rather than crashing. Uevent bursts are handled better by the new batching, but can be more severe due to faster enumeration. Both dropping and crashing have drawbacks, but dropping made it possible to recover on a 32-processor machine with many peripherals.

v0.9.3

• Enhancements
  • Move C build products to under _build

v0.9.2

• Enhancements
  • Support disabling SystemRegistry integration. This is not a recommended setting and should only be used on slow devices that don't need device insertion/removal notifications.

v0.9.1

• Enhancements
  • Filter out synth_uuid from uevent reports since it's not supported by the current uevent handling code.
  • Further reduce garbage produced by processing uevent reports

v0.9.0

The Nerves Runtime Helpers have been extracted and are now part of Toolshed. The helpers included things like cmd/1 and reboot/0 that you could run at the IEx prompt. Toolshed is not included as a dependency. If you would like it, please add toolshed to your application dependencies. You'll find that Toolshed contains more helpers. It is also easier for us to maintain since changes to the helpers no longer affect all Nerves projects.

• Enhancements
  • Further optimize enumeration of devices at boot. This fixes an issue where uniprocessor boards (like the RPi Zero and BBB) would appear to stall momentarily on boot.
  • The U-Boot environment processing code has been factored out of nerves_runtime so that it can be used independently from Nerves. It can be found at uboot_env.

v0.8.0

• Enhancements

  • Optimized enumeration of devices at boot. You will likely notice devices becoming available more quickly. This may uncover race conditions in application initialization code.
  • The syslog monitoring code has been rewritten in pure Elixir. This component captures log messages sent by C programs using the syslog system call so that they can be handled by Elixir Logger backends.
  • The kmsg log monitor still requires C, but the C code is simpler now that it doesn't process syslog messages as well.
  • The Linux uevent processing code was simplified and the C to Elixir communications refactored to minimize processing of events.

• Bug fixes

  • Fixed a race condition with the Linux kernel and processing /sys/devices that could cause an exception during device enumeration.
  • Syslog messages w/o terminating newlines are logged now.

v0.7.0

• Enhancements

  • Documentation updates to nerves_serial_number, nerves_validated, and nerves_autovalidate.

  • Added helper function Nerves.Runtime.KV.UBootEnv.put/2 for writing to the UBoot env. This is useful for setting provisioning information at runtime.

  • Added the ability to mock the contents of Nerves.Runtime.KV for use in test and dev. The contents can be set in your application config.

    config :nerves_runtime, :modules, [

    {Nerves.Runtime.KV.Mock, %{"key" => "value"}}

    ]

• Bug fixes

  • Kernel uevent change messages no longer cause modifications to system_registry.

v0.6.5

Update dependencies to only include dialyxir for [:dev, :test], preventing it from being distributed in the with the hex package. This addresses an issue where dialyxir and its dependencies would be included in the applications list when producing the OTP release and cause :wx to raise because the target version of erts was compiled without it.

v0.6.4

• Bug fixes
  • Fix U-Boot environment load issue and add unit tests to cover environment block generation using either U-Boot tools or fwup
  • Load rngd if available. If it's available, this greatly shortens the time for the Linux kernel's random number entropy pool to initialize. This improves boot time for applications that need random numbers right away.

v0.6.3

• Bug fixes
  • Fix issue with parsing fw_env.config files with space separated values.

v0.6.2

• Enhancements

  • Updates to docs and typespecs.

• Bug fixes

  • Read the U-Boot environment directly using :file if possible. (OTP-21) This fixes an issue with fw_printenv where multi-line values cause the output to be unparseable.

v0.6.1

• Bug fixes
  • Log the output of system commands to that they're easier to review
  • Support mounting f2fs (requires support in the Nerves system to work)

v0.6.0

• New features

  • Forward operating system messages from /dev/log and /proc/kmsg to Elixir's Logger. If the log volume is too much to the console, consider replacing the console logger with ring_logger or another logger backend.

• Bug Fixes

  • cmd/1 helper improvements to interactively print output from long running commands.
  • Nerves.Runtime.revert would always reboot even if told not to.
  • Cleanup throughout to improve docs, formatting, and newer Elixir stylistic conventions
  • Remove scary suid printout when crosscompiling since nothing setuid related was going on.

v0.5.2

• Enhancements

  • Added Nerves.Runtime.revert to revert the device to the inactive firmware. To use this, the Nerves system needs to include revert instructions. This is currently being implemented.

• Bug Fixes

  • Setuid the uevent port binary for debugging on the host.

v0.5.1

• Bug Fixes
  • Split device attributes into only two parts

v0.5.0

• The Nerves runtime shell (the bash shell-like shell from CTRL+G) has been moved to a separate project so that it can evolve independently from nerves_runtime. As such, it's no longer available, but see the nerves_runtime_shell project to include it again.

• Enhancements

  • Force application partition UUID. The UUID has previously been random. The main reason for change is to avoid a delay when waiting for the urandom pool to initialize. Having a known UUID for the application partition may come in handy in the future, though.

v0.4.4

• Enhancements
  • Added installation helper for Nerves.Runtime.Helpers
  • Privatized methods in KV so that they don't show up in the tab complete and help screens.

v0.4.3

• Enhancements
  • The Nerves.Runtime.Helpers module provides a number of functions that are useful when working at the IEx prompt on a target.

v0.4.2

• Enhancements
  • Makefile only builds for Linux hosts or cross compile environments. Allows package to compile on other platforms.

v0.4.1

• Bug Fixes
  • Fixed issue with the order of args being passed to mkfs

v0.4.0

• Enhancements
  • Loosen dependency requirements on SystemRegistry

v0.3.1

• Bug Fixes
  • Increased erl_cmd buffer size to 2048 to prevent segfaults with uevents for devices with many attributes.

v0.3.0

• Enhancements
  • Removed GenStage in favor of SystemRegistry
  • Added KV firmware variable key value store
  • Added Init worker for initializing the application partition

v0.2.0

• Enhancements
  • Moved hardware abstraction layer to separate project for further development
  • Start the shell using the name sh instead of 'Elixir.Nerves.Runtime.Shell'

v0.1.2

• Bug fixes
  • Cleaned up IO
  • Rename host to sh