10. Reference

10.1. System Configuration File

A configuration file located in /etc/rauc/system.conf describes the number and type of available slots. It is used to validate storage locations for update images. Each board type requires its special configuration.

This file is part of the root file system.

Note

When changing the configuration file on your running target you need to restart the RAUC service in order to let the changes take effect.

Example configuration:

[system]
compatible=FooCorp Super BarBazzer
bootloader=barebox
statusfile=/data/central-status.raucs
bundle-formats=-plain

[keyring]
path=/etc/rauc/keyring.pem

[handlers]
system-info=/usr/lib/rauc/info-provider.sh
post-install=/usr/lib/rauc/postinst.sh

[slot.rootfs.0]
device=/dev/sda0
type=ext4
bootname=system0

[slot.rootfs.1]
device=/dev/sda1
type=ext4
bootname=system1

[system] section

compatible
A user-defined compatible string that describes the target hardware as specific enough as required to prevent faulty updating systems with the wrong firmware. It will be matched against the compatible string defined in the update manifest.
bootloader
The bootloader implementation RAUC should use for its slot switching mechanism. Currently supported values (and bootloaders) are barebox, grub, uboot, efi, custom, noop.
bundle-formats

This option controls which bundle formats are allowed when verifying a bundle. You can either specify them explicitly by using a space-separated list for format names (such as plain verity). In this case, any any future changes of the built-in defaults will have no effect.

Alternatively, you can use format names prefixed by - or + (such as -plain) to enable or disable formats relative to the default configuration. This way, formats added in newer releases will be active automatically.

mountprefix
Prefix of the path where bundles and slots will be mounted. Can be overwritten by the command line option --mount. Defaults to /mnt/rauc/.
grubenv
Only valid when bootloader is set to grub. Specifies the path under which the GRUB environment can be accessed.
barebox-statename
Only valid when bootloader is set to barebox. Overwrites the default state state to a user-defined state name. If this key not exists, the bootchooser framework searches per default for /state or /aliases/state.
barebox-dtbpath

Only valid when bootloader is set to barebox. Allows to set a path to a separate devicetree (dtb) file to be used for reading barebox state definition from. This is mainly useful for systems that do not use devicetrees by default, like x86 systems.

Note

Requires to have at least dt-utils version 2021.03.0

boot-attempts
This configures the number of boot attempts to set when a slot is marked good through the D-Bus API or via the command line tool. This is currently only supported when bootloader is set to uboot and defaults to 3 if not set.
boot-attempts-primary
This configures the number of boot attempts to set when a slot is marked as primary (ie, when an update was installed successfully). This is currently only supported when bootloader is set to uboot and defaults to 3 if not set.
efi-use-bootnext
Only valid when bootloader is set to efi. If set to false, this disables using efi variable BootNext for marking a slot primary. This is useful for setups where the BIOS already handles the slot switching on watchdog resets. Behavior defaults to true if option is not set.
activate-installed
This boolean value controls if a freshly installed slot is automatically marked active with respect to the used bootloader. Its default value is true which means that this slot is going to be started the next time the system boots. If the value of this parameter is false the slot has to be activated manually in order to be booted, see section Manually Switch to a Different Slot.
statusfile
This key should be set to point to a central file where slot status information should be stored (e.g. slot-specific metadata, see Slot Status). This file must be located on a non-redundant filesystem which is not overwritten during updates. In most cases, a central status file is preferable to per-slot status files as it allows to store data also for read-only or (temporary) filesystem-less slots. However, if a per-slot status is required as one of the above-noted requirements cannot be met, one can use the value per-slot to document this decision. For background compatibility this option is not mandatory and will default to per-slot status files if not set.
max-bundle-download-size
Defines the maximum downloadable bundle size in bytes, and thus must be a simple integer value (without unit) greater than zero. It overwrites the compiled-in default value of 8388608 (8 MiB).
variant-name
String to be used as variant name for this board. If set, neither variant-file nor variant-dtb must be set. Refer chapter Handling Board Variants With a Single Bundle for more information.
variant-file
File containing variant name for this board. If set, neither variant-name nor variant-dtb must be set. Refer chapter Handling Board Variants With a Single Bundle for more information.
variant-dtb
If set to true, use current device tree compatible as this boards variant name. If set, neither variant-name nor variant-file must be set. Refer chapter Handling Board Variants With a Single Bundle for more information.

[keyring] section

The keyring section refers to the trusted keyring used for signature verification. Both path and directory options can be used together if desired, though only one or the other is necessary to verify the bundle signature.

path
Path to the keyring file in PEM format. Either absolute or relative to the system.conf file.
directory
Path to the keyring directory containing one or more certificates. Each file in this directory must contain exactly one certificate in CRL or PEM format. The filename of each certificate must have the form hash.N for a certificate or hash.rN for CRLs; where hash is obtained by X509_NAME_hash(3) or the --hash option of openssl(1) x509 or crl commands. See documentation in X509_LOOKUP_hash_dir(3) for details.
use-bundle-signing-time=<true/false>
If this boolean value is set to true then the bundle signing time is used instead of the current system time for certificate validation.
check-crl=<true/false>
If this boolean value is set to true, RAUC will enable checking of CRLs (Certificate Revocation Lists) stored in the keyring together with the CA certificates. Note that CRLs have an expiration time in their signature, so you need to make sure you don’t end up with an expired CRL on your device (which would block further updates).
check-purpose
This option can be used to set the OpenSSL certificate purpose used during chain verification. Certificates in the chain with incompatible purposes are rejected. Possible values are provided by OpenSSL (any, sslclient, sslserver, nssslserver, smimesign, smimeencrypt) and RAUC (codesign). See -purpose and VERIFY OPERATION in the OpenSSL verify manual page and the Certificate Key Usage Attributes section for more information.

[casync] section

The casync section contains casync-related settings. For more information about using casync support of RAUC, refer to RAUC casync Support.

storepath
Allows to set the path to use as chunk store path for casync to a fixed one. This is useful if your chunk store is on a dedicated server and will be the same pool for each update you perform. By default, the chunk store path is derived from the location of the RAUC bundle you install.
tmppath
Allows to set the path to use as temporary directory for casync. The temporary directory used by casync can be specified using the TMPDIR environment variable. It falls back to /var/tmp if unset. If tmppath is set then RAUC runs casync with TMPDIR sets to that path. By default, the temporary directory is left unset by RAUC and casync uses its internal default value /var/tmp.

[autoinstall] section

The auto-install feature allows to configure a path that will be checked upon RAUC service startup. If there is a bundle placed under this specific path, this bundle will be installed automatically without any further interaction.

This feature is useful for automatically updating the slot RAUC currently runs from, like for asymmetric redundancy setups where the update is always performed from a dedicated (recovery) slot.

path
The full path of the bundle file to check for. If file at path exists, auto-install will be triggered.

[handlers] section

Handlers allow to customize RAUC by placing scripts in the system that RAUC can call for different purposes. All parameters expect pathnames to the script to be executed. Pathnames are either absolute or relative to the system.conf file location.

RAUC passes a set of environment variables to handler scripts. See details about using handlers in Custom Handlers (Interface).

system-info

This handler will be called when RAUC starts up, right after loading the system configuration file. It is used for obtaining further information about the individual system RAUC runs on. The handler script must print the information to standard output in form of key value pairs KEY=value. The following variables are supported:

RAUC_SYSTEM_SERIAL
Serial number of the individual board
pre-install
This handler will be called right before RAUC starts with the installation. This is after RAUC has verified and mounted the bundle, thus you can access bundle content.
post-install
This handler will be called after a successful installation. The bundle is still mounted at this moment, thus you could access data in it if required.
bootloader-custom-backend

This handler will be called to trigger the following actions:

  • get the primary slot
  • set the primary slot
  • get the boot state
  • set the boot state

if a custom bootloader backend is used. See Custom for more details.

Note

When using a full custom installation (see [handler] section) RAUC will not execute any system handler script.

[slot.<slot-class>.<idx>] section

Each slot is identified by a section starting with slot. followed by the slot class name, and a slot number. The <slot-class> name is used in the update manifest to target the correct set of slots. It must not contain any . (dots) as these are used as hierarchical separator.

device=</path/to/dev>
The slot’s device path. This one is mandatory.
type=<type>
The type describing the slot. Currently supported <type> values are raw, nand, nor, ubivol, ubifs, ext4, vfat. See table Slot Type for a more detailed list of these different types. Defaults to raw if none given.
bootname=<name>
Registers the slot for being handled by the bootselection interface with the <name> specified. The value must be unique across all slots. Only slots without a parent entry can have a bootname. The actual meaning of the name provided depends on the bootloader implementation used.
parent=<slot>
The parent entry is used to bind additional slots to a bootable root file system <slot>. Indirect parent references are discouraged, but supported for now. This is used together with the bootname to identify the set of currently active slots, so that the inactive one can be selected as the update target. The parent slot is referenced using the form <slot-class>.<idx>.
allow-mounted=<true/false>
Setting this entry true tells RAUC that the slot may be updated even if it is already mounted. Such a slot can be updated only by a custom install hook.
readonly=<true/false>
Marks the slot as existing but not updatable. May be used for sanity checking or informative purpose. A readonly slot cannot be a target slot.
install-same=<true/false>

If set to false, this will tell RAUC to skip writing slots that already have the same content as the one that should be installed. Having the ‘same’ content means that the hash value stored for the target slot and the hash value of the update image are equal. The default value is true here, meaning that no optimization will be done as this can be unexpected if RAUC is not the only one that potentially alters a slot’s content.

This replaces the deprecated entries ignore-checksum and force-install-same.

resize=<true/false>
If set to true this will tell RAUC to resize the filesystem after having written the image to this slot. This only has an effect when writing an ext4 file system to an ext4 slot, i.e. if the slot has``type=ext4`` set.
extra-mount-opts=<options>
Allows to specify custom mount options that will be passed to the slots mount call as -o argument value.

10.2. Manifest

The manifest file located in a RAUC bundle describes the images packed in the bundle and their corresponding target slot class.

A valid RAUC manifest file must be named manifest.raucm.

[update]
compatible=FooCorp Super BarBazzer
version=2016.08-1

[bundle]
format=verity
verity-hash=3fcb193cb4fd475aa174efa1f1e979b2d649bf7f8224cc97f4413b5ee141a4e9
verity-salt=4b7b8657d03759d387f24fb7bb46891771e1b370fff38c70488e6381d6a10e49
verity-size=24576

[image.rootfs]
filename=rootfs.ext4
size=419430400
sha256=b14c1457dc10469418b4154fef29a90e1ffb4dddd308bf0f2456d436963ef5b3

[image.appfs]
filename=appfs.ext4
size=219430400
sha256=ecf4c031d01cb9bfa9aa5ecfce93efcf9149544bdbf91178d2c2d9d1d24076ca

[update] section

compatible
A user-defined compatible string that must match the compatible string of the system the bundle should be installed on.
version
A free version field that can be used to provide and track version information. No checks will be performed on this version by RAUC itself, although a handler can use this information to reject updates.
description
A free-form description field that can be used to provide human-readable bundle information.
build
A build id that would typically hold the build date or some build information provided by the bundle creation environment. This can help to determine the date and origin of the built bundle.

[bundle] section

format
Either plain (default) or verity. This selects the format use when wrapping the payload during bundle creation.
verity-hash
The dm-verity root hash over the bundle payload in hexadecimal. RAUC determines this value automatically, so it should be left unspecified when preparing a manifest for bundle creation.
verity-salt
The dm-verity salt over the bundle payload in hexadecimal. RAUC determines this value automatically, so it should be left unspecified when preparing a manifest for bundle creation.
verity-size
The size of the dm-verity hash tree. RAUC determines this value automatically, so it should be left unspecified when preparing a manifest for bundle creation.

[hooks] section

filename
Hook script path name, relative to the bundle content.
hooks

List of hooks enabled for this bundle. See Install Hooks for more details.

Valid items are: install-check

[handler] section

filename
Handler script path name, relative to the bundle content. Used to fully replace default update process.
args
Arguments to pass to the handler script, such as args=--verbose

[image.<slot-class>] section

filename
Name of the image file (relative to bundle content). RAUC uses the file extension and the slot type to decide how to extract the image file content to the slot.
sha256
sha256 of image file. RAUC determines this value automatically when creating a bundle, thus it is not required to set this by hand.
size
size of image file. RAUC determines this value automatically when creating a bundle, thus it is not required to set this by hand.
hooks

List of per-slot hooks enabled for this image. See Slot Hooks for more details.

Valid items are: pre-install, install, post-install

10.3. Bundle Formats

RAUC currently supports two bundle formats (plain and verity) and additional formats could be added to support features such as encryption. Version 1.4 (released on 2020-06-20) and earlier only supported a single format which is now named plain, which should be used as long as compatibility to those versions is required.

The verity format was added to prepare for future use cases (such as network streaming and encryption), for better parallelization of installation with hash verification and to detect modification of the bundle during installation.

The bundle format is detected when reading a bundle and checked against the set of allowed formats configured in the system.conf (see bundle-formats).

10.3.1. plain Format

In this case, a bundle consists of:

  • squashfs filesystem containing manifest and images
  • detached CMS signature over the squashfs filesystem
  • size of the CMS signature

With this format, the signature is checked in a full pass over the squashfs before mounting or accessing it. This makes it necessary to protect the bundle against modification by untrusted processes. To ensure exclusive access, RAUC takes ownership of the file (using chown) and uses file leases to detect other open file descriptors.

10.3.2. verity Format

In this case, a bundle consists of:

  • squashfs filesystem containing manifest (without verity metadata) and images
  • dm-verity hash tree over the squashfs filesystem
  • CMS signature over an inline manifest (with verity metadata)
  • size of the CMS signature

With this format, the manifest is contained in the CMS signature itself, making it accessible without first hashing the full squashfs. The manifest contains the additional metadata (root hash, salt and size) necessary to authenticate the hash tree and in turn each block of the squashfs filesystem.

During installation, the kernel’s verity device mapper target is used on top of the loopback block device to authenticate each filesystem block as needed.

When using rauc extract (or other commands which need access to the squashfs except install), the squashfs is checked before accessing it by RAUC itself without using the kernel’s device mapper target, as they are often used by normal users on their development hosts. It this case, the same mechanism for ensuring exclusive access as with plain bundles is used.

10.3.3. External Signing and PKI

Some industrialization procedures require signing artifacts in a dedicated secure room with restricted access (as Public Key Infrastructure aka PKI).

For this case rauc extract-signature can extract the bundle signature.

As a verity format bundle signature is a detached CMS, you can easily resign it externally. For the plain format bundle signature it’s slightly different, as the signature is detached, it contains just the message digest. You can use openssl asn1parse for retrieving the message digest in the CMS.

Note

The asn1parse method can also be used for the verity bundle

10.4. Slot Status

There is some slot specific metadata that are of interest for RAUC, e.g. a hash value of the slot’s content (SHA-256 per default) that is matched against its counterpart of an image inside a bundle to decide if an update of the slot has to be performed or can be skipped. These slot metadata can be persisted in one of two ways: either in a slot status file stored on each slot containing a writable filesystem or in a central status file that lives on a persistent filesystem untouched by updates. The former is RAUC’s default whereas the latter mechanism is enabled by making use of the optional key statusfile in the system.conf file. Both are formatted as INI-like key/value files where the slot information is grouped in a section named [slot] for the case of a per-slot file or in sections termed with the slot name (e.g. [slot.rootfs.1]) for the central status file:

[slot]
bundle.compatible=FooCorp Super BarBazzer
bundle.version=2016.08-1
bundle.description=Introduction of Galactic Feature XYZ
bundle.build=2016.08.1/imx6/20170324-7
status=ok
sha256=b14c1457dc10469418b4154fef29a90e1ffb4dddd308bf0f2456d436963ef5b3
size=419430400
installed.timestamp=2017-03-27T09:51:13Z
installed.count=3

For a description of sha256 and size keys see this part of the section Manifest. Having the slot’s content’s size allows to re-calculate the hash via head -c <size> <slot-device> | sha256sum or dd bs=<size> count=1 if=<slot-device> | sha256sum.

The properties bundle.compatible, bundle.version, bundle.description and bundle.build are copies of the respective manifest properties. More information can be found in this subsection of section Manifest.

RAUC also stores the point in time of installing the image to the slot in installed.timestamp as well as the number of updates so far in installed.count. Additionally RAUC tracks the point in time when a bootable slot is activated in activated.timestamp and the number of activations in activated.count, see section Manually Switch to a Different Slot. Comparing both timestamps is useful to decide if an installed slot has ever been activated or if its activation is still pending.

10.5. Command Line Tool

Usage:
  rauc [OPTION…] <COMMAND>

Options:
  -c, --conf=FILENAME               config file
  --cert=PEMFILE|PKCS11-URL         cert file or PKCS#11 URL
  --key=PEMFILE|PKCS11-URL          key file or PKCS#11 URL
  --keyring=PEMFILE                 keyring file
  --intermediate=PEMFILE            intermediate CA file name
  --mount=PATH                      mount prefix
  --override-boot-slot=BOOTNAME     override auto-detection of booted slot
  --handler-args=ARGS               extra handler arguments
  -d, --debug                       enable debug output
  --version                         display version
  -h, --help

List of rauc commands:
  bundle                Create a bundle
  resign                Resign an already signed bundle
  convert               Convert classic to casync bundle
  extract-signature     Extract the bundle signature
  extract               Extract the bundle content
  install               Install a bundle
  info                  Show file information
  mount                 Mount a bundle (for development purposes)
  service               Start RAUC service
  status                Show status
  write-slot            Write image to slot and bypass all update logic

Environment variables:
  RAUC_PKCS11_MODULE  Library filename for PKCS#11 module (signing only)
  RAUC_PKCS11_PIN     PIN to use for accessing PKCS#11 keys (signing only)

10.6. Custom Handlers (Interface)

Interaction between RAUC and custom handler shell scripts is done using shell variables.

RAUC_SYSTEM_CONFIG
Path to the system configuration file (default path is /etc/rauc/system.conf)
RAUC_CURRENT_BOOTNAME
Bootname of the slot the system is currently booted from
RAUC_BUNDLE_MOUNT_POINT
Path to mounted update bundle, e.g. /mnt/rauc/bundle
RAUC_UPDATE_SOURCE
A deprecated alias for RAUC_BUNDLE_MOUNT_POINT
RAUC_MOUNT_PREFIX
Provides the path prefix that may be used for RAUC mount points
RAUC_SLOTS
An iterator list to loop over all existing slots. Each item in the list is an integer referencing one of the slots. To get the slot parameters, you have to resolve the per-slot variables (suffixed with <N> placeholder for the respective slot number).
RAUC_TARGET_SLOTS
An iterator list similar to RAUC_SLOTS but only containing slots that were selected as target slots by the RAUC target slot selection algorithm. You may use this list for safely installing images into these slots.
RAUC_SLOT_NAME_<N>
The name of slot number <N>, e.g. rootfs.0
RAUC_SLOT_CLASS_<N>
The class of slot number <N>, e.g. rootfs
RAUC_SLOT_TYPE_<N>
The type of slot number <N>, e.g. raw
RAUC_SLOT_DEVICE_<N>
The device path of slot number <N>, e.g. /dev/sda1
RAUC_SLOT_BOOTNAME_<N>
The bootloader name of slot number <N>, e.g. system0
RAUC_SLOT_PARENT_<N>
The name of slot number <N>, empty if none, otherwise name of parent slot
for i in $RAUC_TARGET_SLOTS; do
        eval RAUC_SLOT_DEVICE=\$RAUC_SLOT_DEVICE_${i}
        eval RAUC_IMAGE_NAME=\$RAUC_IMAGE_NAME_${i}
        eval RAUC_IMAGE_DIGEST=\$RAUC_IMAGE_DIGEST_${i}
done

10.7. Hooks (Interface)

10.7.1. Install Hooks Interface

The following environment variables will be passed to the hook executable:

RAUC_SYSTEM_COMPATIBLE
The compatible value set in the system configuration file, e.g. "My First Product"
RAUC_SYSTEM_VARIANT
The system’s variant as obtained by the variant source (refer ref:sec-variants)
RAUC_MF_COMPATIBLE
The compatible value provided by the current bundle, e.g. "My Other Product"
RAUC_MF_VERSION
The value of the version field as provided by the current bundle, e.g. "V1.2.1-2020-02-28"
RAUC_MOUNT_PREFIX
The global RAUC mount prefix path, e.g. "/run/mount/rauc"

10.7.2. Slot Hooks Interface

The following environment variables will be passed to the hook executable:

RAUC_SYSTEM_COMPATIBLE
The compatible value set in the system configuration file, e.g. "My Special Product"
RAUC_SYSTEM_VARIANT
The system’s variant as obtained by the variant source (refer ref:sec-variants)
RAUC_SLOT_NAME
The name of the currently installed slot, e.g "rootfs.1".
RAUC_SLOT_STATE
The state of the currently installed slot (will always be inactive for slots we install to)
RAUC_SLOT_CLASS
The class of the currently installed slot, e.g. "rootfs"
RAUC_SLOT_TYPE
The type of the currently installed slot, e.g. "ext4"
RAUC_SLOT_DEVICE

The device path of the currently installed slot, e.g. "/dev/mmcblk0p2"

This equals the device= parameter set in the current slot’s system.conf entry and represents the target device RAUC installs the update to. For an install hook, this is the device the hook executable should write to.

RAUC_SLOT_BOOTNAME
For slots with a bootname (those that can be selected by the bootloader), the bootname of the currently installed slot, e.g. "system1" For slots with a parent, the parent’s bootname is used. Note that in many cases, it’s better to use the explicit RAUC_SLOT_NAME to select different behaviour in the hook, than to rely indirectly on the bootname.
RAUC_SLOT_PARENT
If set, the parent of the currently installed slot, e.g. "rootfs.1"
RAUC_SLOT_MOUNT_POINT

If available, the mount point of the currently installed slot, e.g. "/run/mount/rauc/rootfs.1"

For mountable slots, i.e. those with a file system type, RAUC will attempt to automatically mount the slot if a pre-install or post-install hook is given and provide the slot’s current mount point under this env variable.

RAUC_IMAGE_NAME
If set, the file name of the image currently to be installed, e.g. "product-rootfs.img"
RAUC_IMAGE_SIZE
If set, the size of the image currently to be installed, e.g. "82628"
RAUC_IMAGE_DIGEST
If set, the digest of the image currently to be installed, e.g. "e29364a81c542755fd5b2c2461cd12b0610b67ceacabce41c102bba4202f2b43"
RAUC_IMAGE_CLASS
If set, the target class of the image currently to be installed, e.g. "rootfs"
RAUC_MOUNT_PREFIX
The global RAUC mount prefix path, e.g. "/run/mount/rauc"
RAUC_BOOT_PARTITION_ACTIVATING
The to be activated boot partition (0 or 1). boot-mbr-switch, boot-gpt-switch, boot-emmc slot types only.
RAUC_BOOT_PARTITION_START
The absolute partition offset of the to be activated boot partition in bytes. boot-mbr-switch and boot-gpt-switch slot types only.
RAUC_BOOT_PARTITION_SIZE
The partition size of the to be activated boot partition in bytes. boot-mbr-switch and boot-gpt-switch slot types only.

10.8. D-Bus API

RAUC provides a D-Bus API that allows other applications to easily communicate with RAUC for installing new firmware.

de.pengutronix.rauc.Installer

10.8.1. Methods

InstallBundle (IN s source, IN a{sv} args);

Install (IN s source); (deprecated)

Info (IN s bundle, s compatible, s version);

Mark (IN s state, IN s slot_identifier, s slot_name, s message);

GetSlotStatus (a(sa{sv}) slot_status_array);

GetPrimary s primary);

10.8.2. Signals

Completed (i result);

10.8.3. Properties

Operation readable s

LastError readable s

Progress readable (isi)

Compatible readable s

Variant readable s

BootSlot readable s

10.8.4. Description

10.8.5. Method Details

10.8.5.1. The InstallBundle() Method

de.pengutronix.rauc.Installer.InstallBundle()
Install (IN  s source, IN a{sv} args);

Triggers the installation of a bundle. This method call is non-blocking. After completion, the “Completed” signal will be emitted.

IN s source:
Path to bundle to be installed
IN a{sv} args:

Arguments to pass to installation

Currently supported:

STRING ‘ignore-compatible’, VARIANT ‘b’ <true/false>:
 Ignore the default compatible check for forcing installation of bundles on platforms that a compatible not matching the one of the bundle to be installed

10.8.5.2. The Install() Method

Note

This method is deprecated.

de.pengutronix.rauc.Installer.Install()
Install (IN  s source);

Triggers the installation of a bundle. This method call is non-blocking. After completion, the “Completed” signal will be emitted.

IN s source:
Path to bundle to be installed

10.8.5.3. The Info() Method

de.pengutronix.rauc.Installer.Info()
Info (IN  s bundle, s compatible, s version);

Provides bundle info.

IN s bundle:
Path to bundle information should be shown
s compatible:
Compatible of bundle
s version:
Version string of bundle

10.8.5.4. The Mark() Method

de.pengutronix.rauc.Installer.Mark()
Mark (IN  s state, IN  s slot_identifier, s slot_name, s message);

Keeps a slot bootable (state == “good”), makes it unbootable (state == “bad”) or explicitly activates it for the next boot (state == “active”).

IN s state:
Operation to perform (one out of “good”, “bad” or “active”)
IN s slot_identifier:
Can be “booted”, “other” or <SLOT_NAME> (e.g. “rootfs.1”)
s slot_name:
Name of the slot which has ultimately been marked
s message:
Message describing what has been done successfully (e.g. “activated slot rootfs.0”)

10.8.5.5. The GetSlotStatus() Method

de.pengutronix.rauc.Installer.GetSlotStatus()
GetSlotStatus (a(sa{sv}) slot_status_array);

Access method to get all slots’ status.

a(sa{sv}) slot_status_array:
Array of (slotname, dict) tuples with each dictionary representing the status of the corresponding slot

10.8.5.6. The GetPrimary() Method

de.pengutronix.rauc.Installer.GetPrimary()
GetPrimary (s primary);

Get the current primary slot.

10.8.6. Signal Details

10.8.6.1. The “Completed” Signal

de.pengutronix.rauc.Installer::Completed
Completed (i result);

This signal is emitted when an installation completed, either successfully or with an error.

i result:
return code (0 for success)

10.8.7. Property Details

10.8.7.1. The “Operation” Property

de.pengutronix.rauc.Installer:Operation
Operation  readable   s

Represents the current (global) operation RAUC performs. Possible values are idle or installing.

10.8.7.2. The “LastError” Property

de.pengutronix.rauc.Installer:LastError
LastError  readable   s

Holds the last message of the last error that occurred.

10.8.7.3. The “Progress” Property

de.pengutronix.rauc.Installer:Progress
Progress  readable   (isi)

Provides installation progress information in the form

(percentage, message, nesting depth)

Refer Processing Progress Data section.

10.8.7.4. The “Compatible” Property

de.pengutronix.rauc.Installer:Compatible
Compatible  readable   s

Represents the system’s compatible. This can be used to check for usable bundles.

10.8.7.5. The “Variant” Property

de.pengutronix.rauc.Installer:Variant
Variant  readable   s

Represents the system’s variant. This can be used to select parts of an bundle.

10.8.7.6. The “BootSlot” Property

de.pengutronix.rauc.Installer:BootSlot
BootSlot  readable   s

Contains the information RAUC uses to identify the booted slot. It is derived from the kernel command line. This can either be the slot name (e.g. rauc.slot=rootfs.0) or the root device path (e.g. root=PARTUUID=0815). If the root= kernel command line option is used, the symlink is resolved to the block device (e.g. /dev/mmcblk0p1).

10.9. RAUC’s Basic Update Procedure

Performing an update using the default RAUC mechanism will work as follows:

  1. Startup, read system configuration
  2. Determine slot states
  3. Verify bundle signature (reject if invalid)
  4. Mount bundle (SquashFS)
  5. Parse and verify manifest
  6. Determine target install group
    1. Execute pre install handler (optional)
  7. Verify bundle compatible against system compatible (reject if not matching)
  8. Mark target slots as non-bootable for bootloader
  9. Iterate over each image specified in the manifest
    1. Determine update handler (based on image and slot type)
    2. Try to mount slot and read slot status information
      1. Skip update if new image hash matches hash of installed one
    3. Perform slot update (image copy / mkfs+tar extract / …)
    4. Try to write slot status information
  10. Mark target slots as new primary boot source for the bootloader
    1. Execute post install handler (optional)
  11. Unmount bundle
  12. Terminate successfully if no error occurred

10.10. Bootloader Interaction

RAUC comes with a generic interface for interacting with the bootloader. It handles all slots that have a bootname property set.

It provides two base functions:

  1. Setting state ‘good’ or ‘bad’, reflected by API routine r_boot_set_state() and command line tool option rauc status mark <good/bad>
  2. Marking a slot ‘primary’, reflected by API routine r_boot_set_primary() and command line tool option rauc status mark-active

The default flow of how they will be called during the installation of a new bundle (on Slot ‘A’) looks as follows:

_images/bootloader-interaction_install.svg

The aim of setting state ‘bad’ is to disable a slot in a way that the bootloader will not select it for booting anymore. As shown above this is either the case before an installation to make the update atomic from the bootloader’s perspective, or optionally after the installation and a reboot into the new system, when a service detects that the system is in an unusable state. This potentially allows falling back to a working system.

The aim of setting a slot ‘primary’ is to let the bootloader select this slot upon next reboot in case of having completed the installation successfully. An alternative to directly marking a slot primary after installation is to manually mark it primary at a later point in time, e.g. to let a complete set of devices change their software revision at the same time.

Setting the slot ‘good’ is relevant for the first boot but for all subsequent boots, too. In most cases, this interaction with the bootloader is required by the mechanism that enables fallback capability; rebooting a system one or several times without calling rauc status mark-good will let the bootloader boot an alternative system or abort boot operation (depending on configuration). Usually, bootloaders implement this fallback mechanism by some kind of counters they maintain and decrease upon each boot. In these cases marking good means resetting these counters.

A normal reboot of the system will look as follows:

_images/bootloader-interaction_boot.svg

Some bootloaders do not require explicitly setting state ‘good’ as they are able to differentiate between a POR and a watchdog reset, for example.

What the high-level functions described above actually do mainly depends on the underlying bootloader used and the capabilities it provides. Below is a short description about behavior of each bootloader interface currently implemented:

10.10.1. U-Boot

The U-Boot implementation assumes to have variables BOOT_ORDER and BOOT_x_LEFT handled by the bootloader scripting.

state bad:Sets the BOOT_x_LEFT variable of the slot to 0 and removes it from the BOOT_ORDER list
state good:Sets the BOOT_x_LEFT variable back to its default value (3).
primary:Moves the slot from its current position in the list in BOOT_ORDER to the first place and sets BOOT_x_LEFT to its initial value (3). If BOOT_ORDER was unset before, it generates a new list of all slots known to RAUC with the one to activate at the first position.

10.10.2. Barebox

The barebox implementation assumes using barebox bootchooser.

state bad:Sets both the bootstate.systemX.priority and bootstate.systemX.remaining_attempts to 0.
state good:Sets the bootstate.systemX.remaining_attempts to its default value (3).
primary:Sets bootstate.systemX.priority to 20 and all other priorities that were non-zero before to 10. It also sets bootstate.systemX.remaining_attempts to its initial value (3).

10.10.3. GRUB

state bad:Sets slot x_OK to 0 and resets x_TRY to 0.
state good:Sets slot x_OK to 1 and resets x_TRY to 0.
primary:Sets slot x_OK to 1 and resets x_TRY to 0. Sets ORDER to contain slot x as first element and all other after.

10.10.4. EFI

state bad:

Removes the slot from BootOrder

state good:

Prepends the slot to the BootOrder list. This behaves slightly different than the other implementations because we use BootNext for allowing setting primary with an initial fallback option. Setting state good is then used to persist this.

primary:

Sets the slot as BootNext by default. This will make the slot being booted upon next reboot only!

The behavior is different when efi-use-bootnext is set to false. Then this prepends the slot to the BootOrder list as described for ‘state good’.

Note

EFI implementations differ in how they handle new or unbootable targets etc. It may also depend on the actual implementation if EFI variable writing is atomic or not. Thus make sure your EFI works as expected and required.