Hubris

Hubris is a microcontroller operating environment designed for deeply-embedded systems with reliability requirements. Its design was initially proposed in RFD41, but has evolved considerably since then.

Learning

Developer documentation is in Asciidoc in the doc/ directory. It gets rendered via GitHub pages, and is available at https://oxidecomputer.github.io/hubris .

Navigating

The repo is laid out as follows.

• app/ is where the top-level binary crates for applications live, e.g. app/gimlet contains the firmware crate for Gimlet. Generally speaking, if you want to build an image for something, look here.

• build/ contains the build system and supporting crates.

• chip/ contains peripheral definitions and debugging support files for individual microcontrollers.

• doc/ contains developer documentation.

• drv/ contains drivers, a mix of simple driver lib crates and fully-fledged server bin crates. Current convention is that drv/SYSTEM-DEVICE is the driver for DEVICE on SYSTEM (where SYSTEM is usually an SoC name), whereas drv/SYSTEM-DEVICE-server is the server bin crate.

• idl/ contains interface definitions written in Idol

• lib/ contains assorted utility libraries we've written. If you need to make a reusable crate that doesn't fit into one of the other directories, it probably belongs here.

• stage0/ is the bootloader/hypovisor, primarily for LPC55.

• support/ contains some interface and programming support files, like fake certificates and programmer firmware images.

• sys/ contains the "system" bits of Hubris, namely the kernel (sys/kern), the shared crate defining the ABI (sys/abi), and the user library used by tasks (sys/userlib).

• task/ contains reusable tasks that aren't drivers. The distinction between things that live in task vs in drv/something-server is fuzzy. Use your judgement.

• test/ contains the test framework and binary crates for building it for various boards.

• website/ contains the source code for the hubris website

Developing

We currently support Linux and Windows as first-tier platforms. macOS is also used on a daily basis by Oxide employees, but is not tested in CI. The build probably also works on Illumos; if anyone would like to step up to maintain support and a continuous build for Illumos or macOS, we'd love the help.

To submit changes for review, push them to a branch in a fork and submit a pull request to merge that branch into master. For details, see CONTRIBUING.md.

Prereqs

You will need:

• A rustup-based toolchain install. rustup will take care of automatically installing our pinned toolchain version, and the cross-compilation targets, when you first try to build.

• openocd (ideally 0.11) or (if using the LPC55) pyocd (0.27 or later). Note that the 0.10 release of OpenOCD predates the STLink v3. People are using various post-0.10, pre-0.11 builds provided by system package managers, with some success, but if your system isn't packaging 0.11 yet, pester them. If you're going to use Homebrew on macOS to install OpenOCD, you need to use brew install --head openocd to build the tip of the main branch rather than using the latest binary release. If you need to build from source, you can find OpenOCD v0.11.0 here. When running ./configure, make sure that you see that the ST-Link Programmer is set enabled (which should be the default).

• libusb, typically found from your system's package manager as libusb-1.0.0 or similar.

• libfdti1, found as libftdi1-dev or similar.

• arm-none-eabi-objcopy and arm-none-eabi-gdb, typically from your system's package manager using package names like arm-none-eabi-binutils/binutils-arm-none-eabi and arm-none-eabi-gdb/gdb-multiarch. macOS users can run brew install --cask gcc-arm-embedded to install the official ARM binaries.

• The Hubris debugger, Humility. Note that cargo install interacts strangely with the rust-toolchain.toml file present in the root of this repository; if you run the following command verbatim to install Humility, do so from a different directory:

  • cargo install --git https://github.com/oxidecomputer/humility.git --locked humility

Windows

There are three alternative ways to install OpenOCD:

See here for getting the source of openocd or get unofficial binaries.

Alternatively, you can install with chocolatey:

> choco install openocd

Lastly, you could install openocd with scoop:

> scoop bucket add extras
> scoop install openocd

Note: openocd installed via scoop has proven problematic for some users. If you experience problems, try installing via choco or from source (see above).

To use the ST-Link programmer, you'll probably need to install this driver.

It's not necessary to build and run Hubris, but if you want to communicate over a serial link (and that's not supported by your terminal), you'll want to use PuTTY; this guide does a good job of explaining how.

Build

We do not use cargo build or cargo run directly because they are too inflexible for our purposes. We have a complex multi-architecture build, which is a bit beyond them.

Instead, the repo includes a Cargo extension called xtask that namespaces our custom build commands.

cargo xtask dist TOMLFILE builds a distribution image for the application described by the TOML file.

• cargo xtask dist app/demo-stm32f4-discovery/app.toml - stm32f4-discovery
• cargo xtask dist app/demo-stm32f4-discovery/app-f3.toml - stm32f3-discovery
• cargo xtask dist app/lpc55xpresso/app.toml - lpcxpresso55s69
• cargo xtask dist app/demo-stm32g0-nucleo/app-g031.toml - stm32g031
• cargo xtask dist app/demo-stm32g0-nucleo/app-g070.toml - stm32g070
• cargo xtask dist app/demo-stm32g0-nucleo/app-g0b1.toml - stm32g0b1
• cargo xtask dist app/demo-stm32h7-nucleo/app-h743.toml - nucleo-ih743zi2
• cargo xtask dist app/demo-stm32h7-nucleo/app-h753.toml - nucleo-ih753zi
• cargo xtask dist app/gemini-bu/app.toml - Gemini bringup board

Iterating

Because a full image build can take 10 seconds or more, depending on what you've changed, when you're iterating on a task or kernel you'll probably want to build it separately. This is what cargo xtask build is for.

For instance, to build task-ping as it would be built in one of the images, but without building the rest of the demo, run:

$ cargo xtask build app/gimletlet/app.toml ping

Running clippy

The cargo xtask clippy subcommand can be used to run clippy against one or more tasks in the context of a particular image:

$ cargo xtask clippy app/gimletlet/app.toml ping pong

Adding a task

To create your own task, the easiest method is:

• Copy task/template to a new name.
• Edit its Cargo.toml with your name and a new package name.
• Add it to the list of workspace members in the root Cargo.toml.
• Add it to a system image by editing an app.toml file.
• Run cargo xtask build to compile it.

A typical app.toml entry for a small task that uses no memory-mapped peripherals would read

[tasks.name_for_task_in_this_image]
name = "my-task-target-name"
priority = 1
requires = {flash = 1024, ram = 1024}
start = true

Graphing task relationships and priorities

A graph can be generated that show the relationships of the various tasks and their priorities. The resulting file is in Graphvis's dot format. Dot source can be included in Asciidoctor source or rendered to a variety of formats.

To create and view an SVG graph for gimletlet on Ubuntu, ensure that the graphviz package is installed. Then generate the graph:

$ cargo xtask graph -o gimletlet.dot app/gimletlet/app.toml
$ dot -Tsvg gimletlet.dot > gimletlet.svg
$ xdg-open gimletlet.svg

Generating all graphs under Linux

Bash commands to generate all graphs:

  APPS=( $(find app -name '*.toml' ! -name Cargo.toml) )
  for app in "${APPS[@]}"
  do
    out=$(basename ${app//\//_} .toml).dot
    svg=$(basename $out .dot).svg
    cargo xtask graph -o $out $app
    dot -Tsvg $out > $svg
  done
  first="${APPS[0]}"
  out="$(basename ${first//\//_} .toml).dot"
  svg="$(basename $out .dot).svg"
  xdg-open "${svg}"

If eog is the default viewer, opening the first SVG in a directory will allow cycling through all of the available graphs using the same window.

Using Hubris

Hubris is tightly coupled to its debugger, Humility, which is used for the commands below either implicitly (in cargo xtask flash) or explicitly (in cargo xtask humility).

If the humility binary is not available on your $PATH, the HUBRIS_HUMILITY_PATH environment variable may be used to provide the path to the binary.

Flash

An image within a Hubris archive can be flashed directly onto a target board by running cargo xtask flash and specifying the appropriate TOML file. This will run cargo xtask dist and then pass the resulting build archive to humility flash. humility will invoke either OpenOCD or pyOCD to flash the image; the exact invocation depends on the board and is encoded in the build archive.

• LPCXpresso55S69: cargo xtask flash app/lpc55xpresso/app.toml
• STM32F4 Discovery board: cargo xtask flash app/demo-stm32f4-discovery/app.toml
• ST Nucleo-H743ZI2 board: cargo xtask flash app/demo-stm32h7-nucleo/app-h743.toml
• ST Nucleo-H753ZI board: cargo xtask flash app/demo-stm32h7-nucleo/app-h753.toml
• Gemini bringup board: cargo xtask flash app/gemini-bu/app.toml

Running Humility

Humility is run in situ by specifying an archive on a directly connected board, or postmortem by specifying a dump. As a convenience for development, Humility can also be run in situ by specifying the appropriate TOML, e.g. on a machine with an STM32F4 Discovery board directly attached:

$ cargo xtask humility app/demo-stm32f4-discovery/app.toml -- tasks
    Finished dev [optimized + debuginfo] target(s) in 0.17s
     Running `target/debug/xtask humility demo/app.toml -- tasks`
humility: attached via ST-Link
ID ADDR     TASK               GEN STATE    
 0 20000108 jefe                 0 Healthy(InRecv(None))     
 1 20000178 rcc_driver           0 Healthy(InRecv(None))     
 2 200001e8 usart_driver         0 Healthy(InRecv(None))     
 3 20000258 user_leds            0 Healthy(Runnable)          <-
 4 200002c8 ping                48 Healthy(Runnable)         
 5 20000338 pong                 0 Healthy(InRecv(None))     
 6 200003a8 idle                 0 Healthy(Runnable)         

Debugging with GDB

humility includes a gdb subcommand which attaches to a running system using arm-none-eabi-gdb, optionally running its own openocd instance based on configuration data in the build archive.

For convenience, there's also a cargo xtask gdb façade which calls humility with the appropriate build archive:

$ cargo xtask gdb app/demo-stm32f4-discovery/app.toml -- --run-openocd
# ... lots of output elided ...
task_idle::main () at task/idle/src/main.rs:14
14          loop {
Breakpoint 1 at 0x800434c: file /crates.io/cortex-m-rt-0.6.15/src/lib.rs, line 560.
Note: automatically using hardware breakpoints for read-only addresses.
semihosting is enabled

semihosting is enabled

(gdb)

Note that cargo xtask gdb will (by default) also run dist and flash, to ensure that the image on the chip is up to date. The -n/--noflash option skips these steps.

Testing Hubris

The Hubris kernel is tested with a dedicated test image that includes a test runner, assistant and test suite. The test image emits its results via ITM. While these results can be interpreted manually, humility test automates this. humility test itself is most easily run via cargo xtask test, which runs the equivalent of cargo xtask dist, cargo xtask flash and cargo xtask humility test. The exact invocation depends on the board:

• LPCXpresso55S69: cargo xtask test test test/tests-lpc55/app.toml
• STM32F3 Discovery board: cargo xtask test test/tests-stm32fx/app-f3.toml
  Note: for this board, SB10 must be soldered closed for ITM to work
• STM32F4 Discovery board: cargo xtask test test/tests-stm32fx/app.toml
• ST Nucleo-H743ZI2 board: cargo xtask test test/tests-stm32h7/app-h743.toml
• ST Nucleo-H753ZI board: cargo xtask test test/tests-stm32h7/app-h753.toml

Note: cargo xtask humility test runs OpenOCD to connect to the device. You must exit any other instances of OpenOCD that you have connected to the device before running tests.

See the documentation for humility test for details on test results.

Debugging tests

Output from tests is captured by humility test; sys_log!() calls to tests can be added and then captured in a humility test dump. To capture a dump from tests that are otherwise passing, use cargo xtask humility directly and pass the -d flag, e.g.:

$ cargo xtask humility test/tests-stm32fx/app.toml -- test -d
...
humility: attached via ST-Link
humility: TPIU sync packet found at offset 1
humility: ITM synchronization packet found at offset 12
humility: expecting 22 cases
humility: running test_send ... ok
...
humility: running test_timer_notify ... ok
humility: running test_timer_notify_past ... ok
humility: tests completed: pass
humility: test output dumped to hubris.testout.2

if one needs to both run GDB and the test suite, use cargo xtask gdb with the test image's TOML and the appropriate GDB file, and then place breakpoints at the test of interest.

Special cases

Gemini bringup board

See the Gemini Bringup Getting Started docs (internal Oxide repo)

STM32F3 Discovery boards

For the STM32F3 Discovery board, SB10 must be soldered closed for ITM to work! This solder bridge defaults to being open, which leaves SWO disconnected. See the STM32F3 Discovery User Manual (UM1570) for schematic and details.

LPCXpresso55S69 board

To use the LPCXpresso55S69, you will need pyOCD, version 0.27.0 or later.

The LPCXpresso55S69 is somewhat of a mess because the built-on on-chip debugger, LPC-Link2, does not correctly support SWO/SWV

If you have the stock LPC-Link2, it will report itself this way via pyocd list:

$ pyocd list
  #   Probe                                           Unique ID
-----------------------------------------------------------------
  0   NXP Semiconductors LPC-LINK2 CMSIS-DAP V5.361   JSAQCQIQ

It's also possible that you have the Segger J-Link firmware -- firmware that will make its odious presence known by prompting for you to accept license terms whenever running pyocd list!

$ pyocd list
  #   Probe                                                       Unique ID
-----------------------------------------------------------------------------
  0   Segger J-Link LPCXpresso V2 compiled Apr  4 2019 16:54:03   726424936

In either of these cases you must -- as a one-time step -- install new firmware on the LPC-Link2. The new firmware is a build of the (open source) DAPLink, which we affectionally call RickLink after the engineer who managed to get it all built -- no small feat!

There are two files that you will need, both contained in the Hubris repository:

• lpc4322_bl_crc.bin
• lpc4322_lpc55s69xpresso_if_rla_swo_hacks.bin

You will additionally need the LPCScrypt program from NXP.

Here are the steps to install RickLink:

1. Install the DFU jumper. This can be found next to the SWD header on the left side of the board; it is labelled "DFU".

2. Run scripts/boot_lpcscrypt from the installed LPCScrypt software:

$ /usr/local/lpcscrypt/scripts/boot_lpcscrypt 
Looking for DFU devices with VID 1fc9 PID 000c ...
dfu-util -d 1fc9:000c -c 1 -i 0 -t 2048 -R  -D /usr/local/lpcscrypt/scripts/../bin/LPCScrypt_228.bin.hdr
Booted LPCScrypt target (1fc9:000c) with /usr/local/lpcscrypt/scripts/../bin/LPCScrypt_228.bin.hdr
$

3. Run lpcscrypt clockslow:

$ /usr/local/lpcscrypt/bin/lpcscrypt clockslow
$

4. Run lpcscrypt program +w1 0x0 BankA to overwrite existing firmware

$ /usr/local/lpcscrypt/bin/lpcscrypt program +w1 0x0 BankA
................
Programmed 524288 bytes to 0x1a000000 in 2.610s (196.165KB/sec)
$

5. Run lpcscrypt program +c <path-to-lpc4322_bl_crc.bin> BankA:

$ /usr/local/lpcscrypt/bin/lpcscrypt program +c ~/hubris/support/lpc4322_bl_crc.bin BankA
..
Programmed 57344 bytes to 0x1a000000 in 0.827s (67.717KB/sec)
$

6. Assuming it is successful, remove the DFU jumper and disconnect/reconnect USB

7. There should now be a USB mass storage device named MAINTENANCE

# fdisk -l
Disk /dev/nvme0n1: 477 GiB, 512110190592 bytes, 1000215216 sectors
Disk model: Micron 2200S NVMe 512GB
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: A8653F99-39AB-4F67-A9C9-524A2864856E

Device             Start        End   Sectors   Size Type
/dev/nvme0n1p1      2048    1050623   1048576   512M EFI System
/dev/nvme0n1p2   1050624  967393279 966342656 460.8G Linux filesystem
/dev/nvme0n1p3 967393280 1000214527  32821248  15.7G Linux swap


Disk /dev/sda: 64.1 MiB, 67174400 bytes, 131200 sectors
Disk model: VFS
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00000000
# mount /dev/sda /mnt
# ls /mnt
DETAILS.TXT  PRODINFO.HTM
# cat /mnt/DETAILS.TXT
# DAPLink Firmware - see https://mbed.com/daplink
Unique ID: 02360b000d96e4fc00000000000000000000000097969905
HIC ID: 97969905
Auto Reset: 1
Automation allowed: 1
Overflow detection: 1
Daplink Mode: Interface
Interface Version: 0254
Bootloader Version: 0254
Git SHA: f499eb6ec4a847a2b78831fe1acc856fd8eb2f28
Local Mods: 1
USB Interfaces: MSD, CDC, HID, WebUSB
Bootloader CRC: 0x09974fb3
Interface CRC: 0x7174ab4c
Remount count: 0
URL: https://os.mbed.com/platforms/LPCXpresso55S69/

8. Copy lpc4322_lpc55s69xpresso_if_rla_swo_hacks.bin to the USB drive

$ sudo cp ~/hubris/support/lpc4322_lpc55s69xpresso_if_rla_swo_hacks.bin /mnt
$

9. Unmount (or otherwise sync) the USB drive:

# umount /mnt
#

10. Unplug and replug the USB cable.

Verify that you are on the new firmware by running pyocd list:

$ pyocd list
  #   Probe                        Unique ID                                         
-------------------------------------------------------------------------------------
  0   LPCXpresso55S69 [lpc55s69]   02360b000d96e4fc00000000000000000000000097969905  

LPC55S28 on Gemini carrier board

Note that the RickLink running on the LPCXpresso55S69 can also be used as the debugger for the LPC55S28 on the Gemini carrier board. To do this, first, follow all of the instructions above to get RickLink onto your LPCXpresso55S69. Then:

1. Using a soldering iron, solder a two-pin header on J5. J5 can be be found to the left of P1 and below the "Debugger" jumper (J3).

2. Put a jumper on the new header

3. Move the "Debugger" jumper (J3) to "Ext".

4. Use a SWD cable (10-pin 2x5 1.27mm pitch cable) to connect the SWD on the LPCXpresso55S69 to the SWD underneath the carrier board on Gemini (J202)

(To allow your RickLink to once again debug its local LPC55S69, remove the jumper on J5 and move J3 to "Loc".)

Multiple boards simultaneously

If multiple probes are attached, tools may struggle to find the right one at the right time. In particular, OpenOCD will pick the first one that it finds; to force OpenOCD to pick a particular probe, you can ascertain the serial number of the probe (e.g., from humility probe) and then specify that serial number in the corresponding openocd.cfg by adding, e.g.:

interface hla
hla_serial 271828182845904523536028

(Where 271828182845904523536028 is the serial number of the probe.)

Updating ST-Link Firmware if necessary

It is common that debugging dongles, and development boards with embedded debug hardware like the Nucleo series, are delivered with older firmware.

You will not be able to use Humilty with outdated ST-Link firmware. Humility will tell you this is the case, for example when attempting to use humility test:

...
Warn : Adding extra erase range, 0x08020060 .. 0x0803ffff
** Programming Finished **
** Verify Started **
** Verified OK **
** Resetting Target **
humility: test failed: The firmware on the probe is outdated
Error: test failed

Follow this "ST-LINK firmware upgrade" link to find software and instructions necessary to install current firmware.