Static Executables¶

You can produce cross-compiled static executable with dk Exe YourModule.Name where YourModule.Name is the name of your module.

Linking goes through each layer of object files, top to bottom. Any unresolved symbols must be resolved in a layer below it. Only symbols that are needed by the main() function are included in your final executable.

Layer	Asset	Description	Generating Project
Bytecode objects		`ocamlc` generated `.bc` file, converted to multiple object files.	Your project
Bytecode runtime	`dksdk-foundations/<TARGET>-{d,r}/{lib}foundation-databases-<TARGET>-{debug,release}.{a,lib}`	The OCaml runtime and DkSDK-specific replacements and extensions of the OCaml runtime	`dksdk-foundations`
C packages	`dksdk-c-packages/<TARGET>/runtime_static.zip`	Third-party C libraries	`dksdk-c-packages`
dksdk_os	`dksdk-os/<TARGET>/os.zip`	DkSDK Memory Allocation and Logging	`dksdk-ffi-c`
sysroot	`dksdk-os/<TARGET>/sysroot[-api<ANDROID_API_LEVEL>].zip`	System Libraries like the C runtime library	`dksdk-ffi-c`

Layers¶

sysroot layer¶

Operating System	Sysroot Provenance	Licenses Required	Packages	Libraries
Linux	Debian dpkg-cross	LGPLv2.1 GCC Runtime Exception	libc6-dev-amd64-cross libc6-dev-arm64-cross libc6-dev-i386-cross	`libc`, `libm`, `libdl` - GNU libc `libgcc` - GCC Runtime
Android	`./dk dksdk.android.ndk.download`	Android Software Development Kit License Agreement	Android NDK r23b API 21	`libc` - Android Bionic C library.
macOS	must be macOS machine	Xcode and Apple SDKs Agreement
Windows	xwin	MICROSOFT VISUAL C++ 2015 - 2022 RUNTIME		`Crypt32`, `Normaliz`

dksdk_os layer¶

The libraries in the dksdk_os layer provide the implementation of the C headers:

dksdk_os/mem.h
dksdk_os/align.h
dksdk_os/err.h
dksdk_os/logger.h
dksdk_os/loggerconf.h

C packages layer¶

The following C package static libraries are created with vcpkg or cmake:

ssl - Linux only. OpenSSL for curl.
crypto - Linux only. OpenSSL for curl.
nghttp2 - HTTP/2.
z - zlib. Compression for curl.
zstd - Compression for curl.
brotlidec - Compression for curl.
brotlicommon - Compression for curl.
cares - c-ares. Asynchronous DNS resolver.

Bytecode runtime layer¶

This layer is the set of object files for:

The conventional "INRIA" OCaml bytecode runtime, minus any objects in the DkSDK runtime below. The INRIA bytecode libraries are:
- libcamlrun
- libunix
- libthreads
- libcamlstr
The DkSDK runtime which includes:
- static libraries for curl, sqlite3 and ev
- static libraries for stubs between OCaml packages and C:
  - xdg
  - ctypes
  - sqlite3
  - curl
  - integers
  - spawn
  - shexp
  - base
  - posixat
  - tiny_httpd
  - mtime
  - cstruct
  - ptime
  - bigstringaf
  - lwt
  - checkseum
  - stdint
  - digestif
  - mirage-crypto
  - MlFront_ZipFile
  - terminal
- the DkSDK FFI OCaml static library
- a static library "bytemain" containing:
  - the main() C function
  - DkSDK startup objects
  - DkSDK replacements for symbols that are incompatible with static executables:
    - sqlite3_enable_load_extension
  - DkSDK replacement for OCaml callbacks (source available alongside the asset)
  - DkSDK replacement for bytecode interpreter (source available alongside the asset)

Bytecode objects layer¶

The object files are a product of the following steps:

The traditional OCaml .bc bytecode file is compiled with ocamlc from the source code of your project.
dk uses the LLVM Machine Code project to create several object files from the .bc bytecode file.