Configuration¶

VAJAX supports user-level and project-level configuration via TOML files, plus environment variable overrides.

Config Files¶

VAJAX loads configuration from two locations (later overrides earlier):

Source	Path	Use case
User config	`~/.config/vajax/config.toml`	Personal model paths, global preferences
Project config	`vajax.toml` in working directory	Per-project model paths

On Linux/macOS, the user config follows the XDG Base Directory Specification — set $XDG_CONFIG_HOME to override the default ~/.config location.

On Windows, the user config is at %APPDATA%\vajax\config.toml.

Config Schema¶

`[models]` — Search Paths¶

# ~/.config/vajax/config.toml

[models]
# Additional directories to search for .va model files and .sim includes.
# Each path is a directory that may contain .va files directly
# or in subdirectories matching the model name.
paths = [
    "/path/to/my/models",
    "/opt/vacask/devices",
    "~/pdk/models",        # Tilde expansion is supported
]

These paths are used for both load statements (Verilog-A .va models) and include statements (netlist .sim files). Paths that don't exist are silently skipped (logged at DEBUG level).

Environment Variables¶

Model paths¶

VAJAX_MODEL_PATH — colon-separated (; on Windows) list of directories to search for .va model files. These are searched before config file paths.

# Single directory
export VAJAX_MODEL_PATH=/path/to/my/models

# Multiple directories
export VAJAX_MODEL_PATH=/path/to/models1:/path/to/models2

# Windows (PowerShell)
$env:VAJAX_MODEL_PATH = "C:\models1;C:\models2"

Other environment variables¶

Variable	Description
`VAJAX_CACHE_DIR`	Override cache directory (default: `~/.cache/vajax/`)
`VAJAX_NO_PROGRESS`	Set to `1` to disable progress bars
`JAX_PLATFORMS`	Force JAX platform: `cpu`, `cuda`, `gpu`
`JAX_ENABLE_X64`	Enable float64: `1` or `0`

Search Order¶

Both load (VA models) and include (netlist files) use the same search order:

Netlist directory — relative to the file containing the load/include statement
VAJAX_MODEL_PATH — environment variable directories
Config file [models].paths — project config first, then user config
Bundled models — vajax/devices/models/ (resistor, capacitor, etc.)
Vendor directories — vendor/OpenVAF/integration_tests, vendor/VACASK/devices

The first match wins. This means you can override bundled models by placing your version in an earlier search path.

Examples¶

Point to a local PDK¶

# vajax.toml (in project directory)
[models]
paths = ["/opt/pdk/sky130/models"]

Use VACASK models from a separate install¶

# ~/.config/vajax/config.toml
[models]
paths = ["/usr/local/share/vacask/devices"]

Temporary override for a single run¶

VAJAX_MODEL_PATH=/tmp/test_models vajax circuit.sim

Programmatic Access¶

from vajax.user_config import get_config, get_model_paths

# Get merged config dict
config = get_config()

# Get resolved model search paths (existing directories only)
paths = get_model_paths()