Runtime Environment

Riescue’s Runtime Environment (referred to as the “Runtime”) is code included in the final test ELF binary. It initializes the execution environment, schedules tests, handles traps, and manages the End of Test (EOT).

Test vs Runtime

A test ELF can be divided into two parts: the Test and the Runtime. Test Code consists of discrete test cases to be ran in the Test Environment. After Test code is finished, it returns control back to the Runtime environment. It runs in the Test privilege mode.

The Runtime Environment or Runtime is generated by RiescueD and manages startup, scheduling, traps, and the end of test. It runs in the Handler privilege mode.

        %%{init: {'themeVariables': {'fontFamily': 'Fira Code', monospace;}}}%%
flowchart LR

Handler["Runtime<br/>(Handler Privilege)"]
Test["Test<br/>(Test Privilege)"]

Handler --> Test
Test   --> Handler

classDef mMode fill:#5164e0,stroke:#fa512e,stroke-width:3px,color:#fff
classDef handlerMode fill:#fa512e,stroke:#fa512e,stroke-width:3px,color:#000
classDef handlerBlock fill:#FEC3A4,stroke:#FEC3A4,stroke-width:3px,color:#0
classDef testMode fill:#7584e6,stroke:#7584e6,stroke-width:3px,color:#0
classDef testBlock fill:#C0C0E0,stroke:#C0C0E0,stroke-width:3px,color:#0

class Loader,EOT_Final mMode
class Handler handlerMode
class Test testMode

Test Code and Environment

Test Code is the code that is being tested. It can consist of hand written test cases in a directed test or generated by a test generator like RiescueC.

The environment used to run Test Code is the Test Environment. It consists of the paging mode, privilege mode, and virtualization support that a test should be ran with. The Test’s privilege mode or priv_mode is used to run all discrete tests. It can be of any privilege mode except VS , i.e. M, HS, U, or VU.

Test API

Test code runs in the Test privilege mode. It runs until the test ends with a pass or a failure. This can be done by calling the ;#test_passed() or ;#test_failed() directives.

Additionally, tests can request some functionality from the Runtime using the Test API. This includes:

Riescue Directives - used to control test execution
Test Macros - used to assert traps and access Runtime variables

Note

This also inlcudes the syscall API, but in the future this will be moved to macros to simplify the API.

Runtime Code and Environment

Runtime Code is the code that’s used to intialize the Test Environment and run Test Code. It’s ran in the Handler privilege mode which must be greater than or equal to the Test’s privilege mode. It can be M, HS, or VS.

Runtime API

Runtime is generated by RiescueD based on the Test’s configuration and consists of a few different components. Each component has an API that is called by other Runtime components. Test code shouldn’t be accessing these APIs directly.

It’s used to intialize the Test’s environment by setting up paging, virtualization, privilege mode, and trap handling. It has it’s own privilege mode it’s ran with, depending on the Test’s configuration. This Runtime privilege mode or runtime_priv_mode can be of a greater than or equal privilege as the Test’s priv_mode.

Configuration

Each test’s runtime is generated with a single configuration in mind. CLI shows the configuration options available on the command line. This configuration is contained in the FeatMgr class and is used to generate the correct Runtime code.

The input configuration includes:

priv_mode: The Test’s privilege mode
deleg_excp_to: The Runtime’s privilege mode and privilege mode for trap handling. All trap handling and OS code uses this privilege mode.
paging_mode: The Test’s paging mode
env: If the test is virtualized (using Hypervisor) or bare metal
mp: The Test’s multi-processing mode

The FeatMgr class contains all configuration needed to generate the correct Runtime code.

Test Modes

There are a few modes that can be used to generate the test ELF. Some modes cede more control than the default Runtime Environment

The different modes include: - default mode: Test Code + Runtime Code - wysiwyg mode: What You See Is What You Get - Test Code Only - linux mode: Test Code + Runtime’s Scheduler (no trap handling)

wysiwyg mode is useful for early bringup, minimal testbench support, and testing without privileged code.: linux mode is useful for testing with Linux support.

Runtime Components: