---
sidebar_label: dcr.toml overview
---
# dcr.toml
Main project configuration file. Located at the project root.
## Structure
```toml
[package]
# required fields
[build]
# build settings
[build.debug] # optional: debug override
[build.release] # optional: release override
[build.linux] # optional: Linux override
[build.windows] # optional: Windows override
[build.windows.debug] # target + profile combination
[toolchain]
# compiler/linker paths
[dependencies]
# project dependencies
[workspace]
# multi-package configuration
[run]
# run settings
[archive]
# optional: pack FAT disk image after build
```
## [package]
| Field | Required | Description |
|-------|----------|-------------|
| `name` | yes | Project name |
| `version` | yes | Semantic version |
| `type` | no | `app`, `lib`, `none` (defaults to `"none"`) |
| `license` | no | SPDX license identifier |
| `author` | no | Author |
```toml
[package]
name = "my-app"
version = "0.1.0"
type = "app"
license = "MIT"
author = "John Doe"
```
## [build]
...
- `build.qt` — (bool) Enable automatic Qt meta-object handling (MOC, UIC, RCC). Requires `qt6` modules installed via `pkg-config`.
| Field | Default | Description |
|-------|---------|-------------|
| `language` | `"c"` | `"c"`, `"c++"`, `"cpp"`, `"cxx"`, `"asm"`, `"llvm_ir"`, `"llvm-ir"`, `"ll"` (optional, defaults to `"c"`) |
| `standard` | `"c11"` | C standard (`c11`, `c17`, `c23`) |
| `cxx_standard` | — | C++ standard (`c++17`, `c++20`, `c++23`) |
| `compiler` | `"clang"` | Preferred compiler (optional, defaults to `"clang"`) |
| `kind` | `"bin"` | `bin`, `staticlib`, `sharedlib`, `efi`, `elf`, `none`, `custom`, `flat-bin` |
| `target` | host | Target triple for cross-compilation |
| `platform` | `"native"` | `native`, `efi` |
| `cflags` | `[]` | Additional C/C++/ASM flags |
| `ldflags` | `[]` | Additional linker flags |
| `filename` | `""` | Custom output file name |
| `extension` | `""` | Custom file extension (for `flat-bin`, default is `bin`) |
| `roots` | `["src"]` | Source roots: directories and/or individual source/header files |
| `exclude` | `[]` | Exclude patterns |
| `include` | `[]` | Additional include directories |
| `src_disable` | `false` | Disable auto source discovery |
| `inherit` | `false` | Inherit build from workspace root |
| `clean` | `[]` | Glob patterns for custom clean paths |
| `out_dir` | `""` | Custom output directory |
| `workspace_only` | `false` | Workspace-only, not built standalone (no `language`/`compiler` required) |
| `freestanding` | `false` | Compile in freestanding mode (`-ffreestanding` + `-nostdlib -static`) |
| `opt_level` | — | Optimization level: `0`-`3`, `"s"`, `"z"` (derived from profile if omitted) |
| `debug` | profile-based | Emit debug symbols (`-g`): `true` in debug, `false` in release |
| `lto` | `false` | Link-time optimization (`-flto` for both compiler and linker) |
| `strip` | `false` | Strip symbols from output (`-s` in ldflags) |
| `warnings` | `[]` | Warning flags (e.g. `"all"`, `"extra"`, `"pedantic"`); engine adds `-Wall -Wextra` in debug if empty |
| `panic` | `""` | Panic strategy: `"abort"` disables exceptions and unwind tables |
| `codegen-units` | `""` | Max parallel compilation jobs (`"0"` = auto) |
| `qt` | `false` | Enable automatic Qt meta-object handling (MOC, UIC, RCC) |
Settings from raw config (not in typed struct):
- `pkg_config` — list of pkg-config packages
- `ldscript` — linker script path
- `build.steps` / `build.post_steps` — codegen steps
## Per-language overrides: `[build.c]`, `[build.cxx]`, `[build.asm]`, `[build.llvm_ir]`
Each language can have its own table that overrides the flat `[build]` settings:
```toml
[build]
compiler = "clang"
standard = "c11"
[build.c]
standard = "c23"
compiler = "gcc"
[build.cxx]
standard = "c++23"
compiler = "g++"
[build.asm]
compiler = "nasm"
flags = ["-felf64"]
[build.llvm_ir]
compiler = "llc"
```
The flat `[build]` acts as fallback; per-language tables take precedence for their language.
Example:
```toml
[build]
language = "c++"
standard = "c23"
cxx_standard = "c++23"
compiler = "clang"
kind = "sharedlib"
cflags = ["-Wall", "-Wextra"]
opt_level = "z"
lto = true
strip = true
panic = "abort"
codegen-units = "2"
```
## [toolchain]
```toml
[toolchain]
cc = "/usr/bin/clang"
cxx = "/usr/bin/clang++"
as = "/usr/bin/as"
ar = "/usr/bin/ar"
ld = "/usr/bin/ld.lld"
```
Raw config also supports `uic`, `moc`, `rcc` for Qt codegen.
## [dependencies]
See [dependencies](/docs/reference/dependencies).
## [run]
```toml
[run]
cmd = "./target/{profile}/{name}"
```
Substitutions:
- `{version}` — package version
- `{version_major}`, `{version_minor}`, `{version_patch}`, `{version_suffix}`, `{version_suffix_dash}` — version parts
- `{profile}` — debug / release
- `{name}` — package name
Default `cmd` = `./target/{profile}/{name}` (macOS/Windows) or `./target/<triple>/<profile>/<name>` (Linux).
## [workspace]
See [workspaces](/docs/reference/workspaces).
## [archive]
Optional post-build step: format a FAT volume and copy built artifacts into a disk image. Runs after a successful package build (and after workspace member builds that define `[archive]`).
Requires DCR built with the `archive` Cargo feature (`cargo build --features archive`). Release binaries include this feature.
| Field | Required | Description |
|-------|----------|-------------|
| `output` | yes | Image path relative to project root (`{profile}` allowed) |
| `format` | yes | `fat12`, `fat16`, or `fat32` |
| `size` | no | Image size: bytes or `K`/`KB`/`M`/`MB`/`G`/`GB` (default `1474560` ≈ 1.44 MiB) |
| `offset` | no | Byte offset of the FAT volume inside the image (default `0`) |
| `label` | no | Volume label (max 11 chars, default `VOLUME`) |
| `bootsector` | no | Path to a 512-byte boot sector written at offset 0 when `offset` is 0 (`{profile}` allowed) |
| `layout` | no | List of `{ from, to }` entries (files or globs → path inside the volume) |
```toml
[archive]
output = "target/{profile}/disk.img"
format = "fat12"
size = "1440K"
label = "MYOS"
bootsector = "target/{profile}/boot.bin"
[[archive.layout]]
from = "target/{profile}/kernel.bin"
to = "KERNEL.BIN"
[[archive.layout]]
from = "assets/*"
to = "/"
```
Typical pairing with `kind = "flat-bin"` (NASM `-f bin`) for bootloaders and pure-ASM OS images.
## `flat-bin` (kind)
Produces a raw binary (default extension `bin`) for boot sectors, kernels, and freestanding payloads.
### Assemblers
| Tool | Language / compiler | How flat-bin is produced |
|------|---------------------|--------------------------|
| NASM | `language = "asm"`, `compiler = "nasm"` | `-f bin` → `<stem>.bin` |
| FASM | `compiler = "fasm"` | direct write (use `format binary` in source) |
| GAS | `compiler = "as"` / `"gas"` | assemble → `objcopy -O binary` |
| MASM | `compiler = "ml"` / `"ml64"` | assemble → `objcopy -O binary` |
| LLC | `language = "llvm_ir"`, `compiler = "llc"` | `-filetype=obj` → `objcopy -O binary` |
```toml
[build]
language = "asm"
compiler = "nasm"
kind = "flat-bin"
extension = "bin"
roots = ["src/boot.asm"]
```
### C / C++
Compile all sources, link with `-nostdlib -static` (plus your `ldflags` / `ldscript`), then convert the intermediate ELF/PE with `objcopy -O binary` to `<filename|name>.bin`.
```toml
[build]
language = "c"
compiler = "clang"
kind = "flat-bin"
freestanding = true
filename = "kernel"
extension = "bin"
ldscript = "linker.ld"
ldflags = ["-T", "linker.ld"]
```
Notes:
- Multi-file **ASM** packages emit one `<stem>.bin` per source; **C/C++** emit a single project binary.
- `objcopy` tools tried in order: `llvm-objcopy`, `objcopy`, `gobjcopy`.
- Incompatible with `build.qt = true`.
- `dcr run` rejects `flat-bin` (not a host executable).