Build iwasm

WAMR vmcore is the runtime library set that loads and runs Wasm modules. This guide walks you through building the WAMR vmcore.

References:

• how to build iwasm: build for Linux, Windows, macOS, and more

• Blog: Introduction to WAMR running modes

building configurations

Include the script runtime_lib.cmake from build-scripts into your CMakeLists.txt to pull vmcore into your build.

# add this into your CMakeLists.txt
include (${WAMR_ROOT_DIR}/build-scripts/runtime_lib.cmake)
add_library(vmlib ${WAMR_RUNTIME_LIB_SOURCE})

The runtime_lib.cmake script exposes variables that control WAMR runtime features. Set them in CMakeLists.txt or pass them on the cmake command line.

# Set flags in CMakeLists.txt
set(WAMR_BUILD_AOT 1)
set(WAMR_BUILD_JIT 0)
set(WAMR_BUILD_LIBC_BUILTIN 1)
set(WAMR_BUILD_LIBC_WASI 1)
# Include the runtime lib script
include (${WAMR_ROOT_DIR}/build-scripts/runtime_lib.cmake)
add_library(vmlib ${WAMR_RUNTIME_LIB_SOURCE})

All compilation flags

Compilation flags	Description
WAMR_APP_THREAD_STACK_SIZE_MAX	Maximum stack size for app threads
WAMR_BH_LOG	Host defined logging
WAMR_BH_VPRINTF	Host defined vprintf
WAMR_BUILD_ALLOC_WITH_USAGE	Allocation with usage tracking
WAMR_BUILD_ALLOC_WITH_USER_DATA	Allocation with user data
WAMR_BUILD_AOT	AoT compilation(wamrc)
WAMR_BUILD_AOT	AoT runtime
WAMR_BUILD_AOT_INTRINSICS	AoT intrinsics
WAMR_BUILD_AOT_STACK_FRAME	AoT stack frame
WAMR_BUILD_AOT_VALIDATOR	AoT validator
WAMR_BUILD_BULK_MEMORY	bulk memory
WAMR_BUILD_COPY_CALL_STACK	copy call stack
WAMR_BUILD_CUSTOM_NAME_SECTION	name section
WAMR_BUILD_DEBUG_AOT	debug AoT
WAMR_BUILD_DEBUG_INTERP	debug interpreter
WAMR_BUILD_DUMP_CALL_STACK	dump call stack
WAMR_BUILD_DYNAMIC_AOT_DEBUG	dynamic AoT debugging
WAMR_BUILD_EXCE_HANDLING	exception handling
WAMR_BUILD_EXTENDED_CONST_EXPR	extended constant expressions
WAMR_BUILD_FAST_INTERP	fast interpreter
WAMR_BUILD_FAST_JIT	fast JIT
WAMR_BUILD_FAST_JIT_DUMP	fast JIT dump
WAMR_BUILD_GC	garbage collection
WAMR_BUILD_GC_HEAP_VERIFY	garbage collection heap verification
WAMR_BUILD_GC_HEAP_SIZE_DEFAULT	default garbage collection heap size
WAMR_BUILD_GLOBAL_HEAP_POOL	global heap pool
WAMR_BUILD_GLOBAL_HEAP_SIZE	global heap size
WAMR_BUILD_INSTRUCTION_METERING	instruction metering
WAMR_BUILD_INTERP	interpreter
WAMR_BUILD_INVOKE_NATIVE_GENERAL	FFI general
WAMR_BUILD_JIT	JIT compilation
WAMR_BUILD_LAZY_JIT	lazy JIT compilation
WAMR_BUILD_LIBC_BUILTIN	libc builtin functions
WAMR_BUILD_LIBC_EMCC	libc emcc compatibility
WAMR_BUILD_LIBC_UVWASI	libc uvwasi compatibility
WAMR_BUILD_LIBC_WASI	wasi libc
WAMR_BUILD_LIB_PTHREAD	pthread library
WAMR_BUILD_LIB_PTHREAD_SEMAPHORE	pthread semaphore support
WAMR_BUILD_LIB_RATS	RATS library
WAMR_BUILD_LIB_WASI_THREADS	wasi threads
WAMR_BUILD_LINUX_PERF	Linux performance counters
WAMR_BUILD_LIME1	LIME1 runtime
WAMR_BUILD_LOAD_CUSTOM_SECTION	loading custom sections
WAMR_BUILD_MEMORY64	memory64 support
WAMR_BUILD_MEMORY_PROFILING	memory profiling
WAMR_BUILD_MINI_LOADER ⚠️ ❗	mini loader
WAMR_BUILD_MODULE_INST_CONTEXT	module instance context
WAMR_BUILD_MULTI_MEMORY	multi-memory support
WAMR_BUILD_MULTI_MODULE	multi-module support
WAMR_BUILD_PERF_PROFILING	performance profiling
WAMR_BUILD_PLATFORM	Default platform
WAMR_BUILD_QUICK_AOT_ENTRY	quick AOT entry
WAMR_BUILD_REF_TYPES	reference types
WAMR_BUILD_SANITIZER	sanitizer
WAMR_BUILD_SGX_IPFS	Intel Protected File System support
WAMR_BUILD_SHARED_HEAP	shared heap
WAMR_BUILD_SHARED_MEMORY	shared memory
WAMR_BUILD_SHRUNK_MEMORY	shrunk memory
WAMR_BUILD_SIMD	SIMD support
WAMR_BUILD_SIMDE	SIMD E extensions
WAMR_BUILD_SPEC_TEST	spec test
WAMR_BUILD_STACK_GUARD_SIZE	Stack guard size
WAMR_BUILD_STATIC_PGO	Static PGO
WAMR_BUILD_STRINGREF	String reference support
WAMR_BUILD_TAIL_CALL	Tail call optimization
WAMR_BUILD_TARGET	Default target architecture
WAMR_BUILD_THREAD_MGR	Thread manager
WAMR_BUILD_WAMR_COMPILER	WAMR compiler
WAMR_BUILD_WASI_EPHEMERAL_NN	WASI ephemeral NN
WAMR_BUILD_WASI_NN	WASI NN
WAMR_BUILD_WASI_NN_EXTERNAL_DELEGATE_PATH	External delegate path for WASI NN
WAMR_BUILD_WASI_NN_ENABLE_GPU	GPU support for WASI NN
WAMR_BUILD_WASI_NN_LLAMACPP	LLAMA CPP for WASI NN
WAMR_BUILD_WASI_NN_ONNX	ONNX for WASI NN
WAMR_BUILD_WASI_NN_OPENVINO	OpenVINO for WASI NN
WAMR_BUILD_WASI_NN_TFLITE	TFLite for WASI NN
WAMR_BUILD_WASM_CACHE	WASM cache
WAMR_CONFIGURABLE_BOUNDS_CHECKS ⚠️ ❗	Configurable bounds checks
WAMR_DISABLE_APP_ENTRY	Disable app entry
WAMR_DISABLE_HW_BOUND_CHECK	Disable hardware bound check
WAMR_DISABLE_STACK_HW_BOUND_CHECK	Disable stack hardware bound check
WAMR_DISABLE_WAKEUP_BLOCKING_OP	Disable wakeup blocking operation
WAMR_DISABLE_WRITE_GS_BASE	Disable write GS base
WAMR_TEST_GC	Test garbage collection

Privileged Features ⚠️ ❗

Privileged Features are powerful options that can boost performance or add capabilities but lower security by compromising isolation. Use them with care and test thoroughly.

config.h

Above compilation flags map to macros in config.h. For example, WAMR_BUILD_AOT maps to WAMR_BUILD_AOT in config.h. The build system sets these macros automatically based on your CMake settings. If your build doesn't set those flags, default values in config.h apply.

Configure platform and architecture

• WAMR_BUILD_PLATFORM: set the target platform. Match the platform folder name under core/shared/platform.

• WAMR_BUILD_TARGET: set the target CPU architecture. Supported targets: X86_64, X86_32, AARCH64, ARM, THUMB, XTENSA, ARC, RISCV32, RISCV64, and MIPS.

  • For ARM and THUMB, use <arch>[<sub-arch>][_VFP]. <sub-arch> is the ARM sub-architecture. _VFP means arguments and returns use VFP coprocessor registers s0-s15 (d0-d7). Both are optional, for example ARMV7, ARMV7_VFP, THUMBV7, or THUMBV7_VFP.

  • For AARCH64, use <arch>[<sub-arch>]. VFP is on by default. <sub-arch> is optional, for example AARCH64, AARCH64V8, or AARCH64V8.1.

  • For RISCV64, use <arch>[_abi]. _abi is optional. Supported: RISCV64, RISCV64_LP64D, and RISCV64_LP64. RISCV64 and RISCV64_LP64D both use LP64D (LP64 with hardware floating-point for FLEN=64). RISCV64_LP64 uses LP64 (integer calling convention only; no hardware floating-point calling convention).

  • For RISCV32, use <arch>[_abi]. _abi is optional. Supported: RISCV32, RISCV32_ILP32D, RISCV32_ILP32F, and RISCV32_ILP32. RISCV32 and RISCV32_ILP32D both use ILP32D (ILP32 with hardware floating-point for FLEN=64). RISCV32_ILP32F uses ILP32F (ILP32 with hardware floating-point for FLEN=32). RISCV32_ILP32 uses ILP32 (integer calling convention only).

cmake -DWAMR_BUILD_PLATFORM=linux -DWAMR_BUILD_TARGET=ARM

Configure interpreters

• WAMR_BUILD_INTERP=1/0: turn the WASM interpreter on or off.

• WAMR_BUILD_FAST_INTERP=1/0: pick fast (default) or classic interpreter.

[!NOTE] The fast interpreter runs ~2X faster than classic interpreter, but consumes about 2X memory to hold the pre-compiled code.

Configure AOT

• WAMR_BUILD_AOT=1/0: turn AOT on or off. Defaults to on.

• WAMR_BUILD_WAMR_COMPILER=1/0. It is used to wasm loader and compilation to indictate compiler mode.

Configure LLVM JIT

Comparing with fast JIT, LLVM JIT covers more architectures and produces better optimized code, but takes longer on cold start.

• WAMR_BUILD_JIT=1/0: turn LLVM JIT on or off. Defaults to off.

• WAMR_BUILD_LAZY_JIT=1/0: turn lazy JIT on or off. Defaults to off. With lazy JIT, functions are compiled in background threads before they are called, which can reduce startup time for large modules.

Configure Fast JIT

The fast JIT is a lightweight JIT that emits code quickly and tunes hot functions.

• WAMR_BUILD_FAST_JIT=1/0: turn Fast JIT on or off. Defaults to off.

• WAMR_BUILD_FAST_JIT_DUMP=1/0: dump fast JIT compiled code to stdout for debugging. Defaults to off.

[!WARNING] It currently covers only a few architectures (x86_64).

Configure Multi-tier JIT

Use fast jit as the first tier and LLVM JIT as the second tier.

• With WAMR_BUILD_FAST_JIT=1 and WAMR_BUILD_JIT=1, you get multi-tier JIT. Defaults to off.

[!WARNING] It currently covers only a few architectures (x86_64).

Configure LIBC

• WAMR_BUILD_LIBC_BUILTIN=1/0: build the built-in libc subset for WASM apps. Defaults to on.

• WAMR_BUILD_LIBC_WASI=1/0: build the WASI libc subset for WASM apps. Defaults to on.

• WAMR_BUILD_LIBC_UVWASI=1/0 (Experiment): build the WASI libc subset for WASM apps using uvwasi. Defaults to off.

• WAMR_BUILD_LIBC_EMCC=1/0: build the emcc-compatible libc subset for WASM apps. Defaults to off.

[!WARNING] WAMR is not a secure sandbox on every platform. On platforms where WAMR_BUILD_LIBC_WASI is unsupported (for example Windows), you can try the uvwasi-based WASI via WAMR_BUILD_LIBC_UVWASI, but it is unsafe.

Multi-Module feature

• WAMR_BUILD_MULTI_MODULE=1/0, default to off.

[!NOTE] See Multiple Modules as Dependencies for details.

[!WARNING] The multi-module feature is not supported in fast-jit or llvm-jit modes.

WASM mini loader

• WAMR_BUILD_MINI_LOADER=1/0, default to off.

[!NOTE] The mini loader skips integrity checks on the WASM binary. Make sure the file is valid yourself.

[!WARNING] This is a privileged feature that compromises security. Use it only when you trust the WASM binary source.

shared memory feature

• WAMR_BUILD_SHARED_MEMORY=1/0, default to off.

bulk memory feature

• WAMR_BUILD_BULK_MEMORY=1/0, default to off.

memory64 feature

• WAMR_BUILD_MEMORY64=1/0, default to off.

[!WARNING] Supported only in classic interpreter mode and AOT mode.

thread manager

• WAMR_BUILD_THREAD_MGR=1/0, default to off.

lib-pthread

• WAMR_BUILD_LIB_PTHREAD=1/0, default to off.

[!NOTE] When you enable lib pthread, required features such as shared memory and thread manager are enabled automatically. See WAMR pthread library for details.

lib-pthread-semaphore

• WAMR_BUILD_LIB_PTHREAD_SEMAPHORE=1/0, default to off.

[!NOTE] This depends on lib-pthread and turns it on automatically.

lib wasi-threads

• WAMR_BUILD_LIB_WASI_THREADS=1/0, default to off.

[!NOTE] Enabling lib wasi-threads also enables its dependencies shared memory and thread manager. See wasi-threads and Introduction to WAMR WASI threads for details.

lib wasi-nn

• WAMR_BUILD_WASI_NN=1/0, default to off.

• WAMR_BUILD_WASI_NN_LLAMACPP=1/0, default to off.

• WAMR_BUILD_WASI_NN_ONNX=1/0, default to off.

• WAMR_BUILD_WASI_NN_OPENVINO=1/0, default to off.

• WAMR_BUILD_WASI_NN_TFLITE=1/0, default to off.

[!NOTE] Using WAMR_BUILD_WASI_NN without WAMR_BUILD_WASI_EPHEMERAL_NN is deprecated and may be removed later. Please enable WAMR_BUILD_WASI_EPHEMERAL_NN too. See WASI-NN for details.

lib wasi-nn GPU mode

• WAMR_BUILD_WASI_NN_ENABLE_GPU=1/0, default to off.

lib wasi-nn external delegate mode

• WAMR_BUILD_WASI_NN_ENABLE_EXTERNAL_DELEGATE=1/0, default to off.

• WAMR_BUILD_WASI_NN_EXTERNAL_DELEGATE_PATH=Path to the external delegate shared library (for example libedgetpu.so.1.0 for Coral USB).

lib wasi-nn with wasi_ephemeral_nn module support

• WAMR_BUILD_WASI_EPHEMERAL_NN=1/0, default to on.

Disable boundary check with hardware trap

• WAMR_DISABLE_HW_BOUND_CHECK=1/0, default to on if the platform supports it. Otherwise, software boundary checks are used.

[!NOTE] By default only linux/darwin/android/windows/vxworks 64-bit platforms enable this hardware trap boundary check. On 32-bit platforms it is off even if the flag is 0. The wamrc tool omits boundary check instructions in AOT code for all 64-bit targets except SGX to improve speed. The boundary check covers linear memory access and native stack access unless WAMR_DISABLE_STACK_HW_BOUND_CHECK is set.

Disable native stack boundary check with hardware trap

• WAMR_DISABLE_STACK_HW_BOUND_CHECK=1/0, default to on if the platform supports it; same rule as WAMR_DISABLE_HW_BOUND_CHECK. Otherwise, software boundary checks are used.

[!NOTE] If hardware trap boundary checks are off (or WAMR_DISABLE_HW_BOUND_CHECK is 1), native stack boundary checks are also off regardless of WAMR_DISABLE_STACK_HW_BOUND_CHECK. If hardware trap boundary checks are on, this setting decides whether the native stack check is on.

Disable async wakeup of blocking operation

• WAMR_DISABLE_WAKEUP_BLOCKING_OP=1/0, default to on when the platform supports it.

[!NOTE] This feature lets blocking threads terminate asynchronously. If you disable it, blocking threads may never finish when asked to exit.

tail call feature

• WAMR_BUILD_TAIL_CALL=1/0, default to off.

128-bit SIMD feature

• WAMR_BUILD_SIMD=1/0, default to on.

• WAMR_BUILD_SIMDE=1/0, default to off.

SIMDE (SIMD Everywhere) implements SIMD operations in fast interpreter mode.

[!WARNING] Supported in AOT, JIT, and fast-interpreter modes with the SIMDe library.

SIMDe library for SIMD in fast interpreter

• WAMR_BUILD_LIB_SIMDE=1/0, default to off.

[!NOTE] When enabled, SIMDe (SIMD Everywhere) implements SIMD operations in fast interpreter mode.

Exception Handling

• WAMR_BUILD_EXCE_HANDLING=1/0, default to off.

[!NOTE] Current implementation supports only Legacy Wasm exception handling proposal, not the latest version.

[!WARNING] Exception handling currently works only in classic interpreter mode.

Garbage Collection

• WAMR_BUILD_GC=1/0, default to off.

• WAMR_BUILD_GC_HEAP_VERIFY=1/0, default to off. When enabled, verifies the heap during free.

• WAMR_BUILD_STRINGREF=1/0, default to off. When enabled, need to set WAMR_STRINGREF_IMPL_SOURCE as well

[!WARNING] Garbage collection is not supported in fast-jit mode and multi-tier-jit mode.

Set the Garbage Collection heap size

• WAMR_BUILD_GC_HEAP_SIZE_DEFAULT=n, default to 128 kB (131072).

Multi Memory

• WAMR_BUIL_MULTI_MEMORY=1/0, default to off.

[!WARNING] Multi memory is supported only in classic interpreter mode.

Name Section

• WAMR_BUILD_CUSTOM_NAME_SECTION=1/0: load function names from the custom name section. Default is off.

AOT stack frame feature

• WAMR_BUILD_AOT_STACK_FRAME=1/0, default to off.

[!NOTE] When enabled, AOT or JIT stack frames (similar to classic interpreter frames but storing only what is needed) are built during calls. Add --enable-dump-call-stack to wamrc when compiling AOT modules.

dump call stack feature

• WAMR_BUILD_DUMP_CALL_STACK=1/0, default to off.

[!NOTE] When enabled, the runtime dumps the call stack on exceptions.

• In interpreter mode, names come first from the custom name section. If that section is absent or disabled, names come from import/export sections.

• In AOT/JIT mode, names come from the import/export section. Export as many functions as possible (for wasi-sdk you can use -Wl,--export-all) when compiling the wasm module, and add --enable-dump-call-stack --emit-custom-sections=name to wamrc when compiling the AOT module.

memory profiling (Experiment)

• WAMR_BUILD_MEMORY_PROFILING=1/0, default to off.

[!NOTE] When enabled, call void wasm_runtime_dump_mem_consumption(wasm_exec_env_t exec_env) to dump memory usage. Currently only module, module_instance, and exec_env memory are measured; other components such as wasi-ctx, multi-module, and thread-manager are not included. See Memory usage estimation for a module.

performance profiling (Experiment)

• WAMR_BUILD_PERF_PROFILING=1/0, default to off.

[!NOTE] When enabled, call void wasm_runtime_dump_perf_profiling(wasm_module_inst_t module_inst) to dump per-function performance. Function name lookup follows the same order as the dump call stack feature. See Tune the performance of running wasm/aot file.

A pre-allocation for runtime and wasm apps

• WAMR_BUILD_GLOBAL_HEAP_POOL=1/0, default to off for iwasm apps except on Alios and Zephyr.

• WAMR_BUILD_GLOBAL_HEAP_SIZE=n, default to 10 MB (10485760) for iwasm apps, except Alios (256 kB), Riot (256 kB), and Zephyr (128 kB).

[!NOTE] When enabled, WAMR uses a big global heap for runtime and wasm apps instead of allocating memory from the system directly. This can reduce memory fragmentation and improve performance when many small allocations happen. The global heap is allocated at startup. WAMR_BUILD_GLOBAL_HEAP_POOL applies to iwasm apps in product-mini. For your own host app, set mem_alloc_type to Alloc_With_Pool if you want to use a global heap. The global heap is described in Memory model and memory usage tunning. WAMR_BUILD_GLOBAL_HEAP_SIZE applies to iwasm apps in product-mini. For your host app, set mem_alloc_option.pool with the size you want for the global heap. The global heap is described in Memory model and memory usage tunning.

Set maximum app thread stack size

• WAMR_APP_THREAD_STACK_SIZE_MAX=n, default to 8 MB (8388608).

[!NOTE] AOT boundary checks with hardware traps may use large stacks because the OS can grow stacks lazily when a guard page is hit. Use this setting to cap total stack use, for example -DWAMR_APP_THREAD_STACK_SIZE_MAX=131072 (128 KB).

Host defined vprintf

• WAMR_BH_VPRINTF=<vprintf_callback>, default to off.

[!NOTE] If you provide vprintf_callback, os_printf() and os_vprintf() on Linux, Darwin, Windows, VxWorks, Android, and esp-idf, plus WASI libc output, call your callback instead of libc vprintf(). Example outside the runtime lib:

int my_vprintf(const char *format, va_list ap)
{
    /* output to pre-opened file stream */
    FILE *my_file = ...;
    return vfprintf(my_file, format, ap);
    /* or output to pre-opened file descriptor */
    int my_fd = ...;
    return vdprintf(my_fd, format, ap);
    /* or output to string buffer and print the string */
    char buf[128];
    vsnprintf(buf, sizeof(buf), format, ap);
    return my_printf("%s", buf);
}

Then run cmake -DWAMR_BH_VPRINTF=my_vprintf .., or add the compiler macro BH_VPRINTF=my_vprintf (for example add_definitions(-DBH_VPRINTF=my_vprintf) in CMakeLists.txt). See basic sample for an example.

WAMR_BH_LOG=<log_callback>, default to off.

[!NOTE] If you provide log_callback, WAMR logs go there. Example:

void my_log(uint32 log_level, const char *file, int line, const char *fmt, ...)
{
    /* Usage of custom logger */
}

See basic sample for an example.

reference types feature

• WAMR_BUILD_REF_TYPES=1/0, default to on.

Exclude WAMR application entry functions

• WAMR_DISABLE_APP_ENTRY=1/0, default to off.

[!NOTE] The WAMR application entry (core/iwasm/common/wasm_application.c) wraps common steps to instantiate and run wasm functions and print results. These use platform APIs. this flag to skip the file if your platform lacks those APIs. Do not enable this flag when building product-mini.

source debugging features

• WAMR_BUILD_DEBUG_INTERP=1/0, default to off.

• WAMR_BUILD_DEBUG_AOT=1/0, default to off.

• WAMR_BUILD_DYNAMIC_AOT_DEBUG=1/0, default to off.

[!NOTE] Source debugging needs extra setup. See source_debugging.md and WAMR source debugging basic.

load wasm custom sections

• WAMR_BUILD_LOAD_CUSTOM_SECTION=1/0, default to off.

[!NOTE] By default, custom sections are ignored. WAMR_BUILD_LOAD_CUSTOM_SECTION so the embedder can read them via wasm_runtime_get_custom_section. If WAMR_BUILD_CUSTOM_NAME_SECTION is on, the custom name section is consumed by the runtime and unavailable to the embedder. For AoT files, pass --emit-custom-sections to wamrc to keep the sections; otherwise they are dropped.

Stack guard size

• WAMR_BUILD_STACK_GUARD_SIZE=n, default to N/A when not set.

[!NOTE] By default, stack guard size is 1K (1024) or 24K when uvwasi is enabled.

Disable writing the linear memory base address to x86 GS segment register

• WAMR_DISABLE_WRITE_GS_BASE=1/0, default to on if the platform supports it.

[!NOTE] By default only linux x86-64 enables this. On 32-bit platforms it stays off even if set to 0. On linux x86-64, writing the linear memory base to the GS segment can speed up linear memory access for LLVM AOT/JIT when --enable-segue=[<flags>] is passed to wamrc or iwasm.

See segue optimization for wamrc when generating the aot file for details.

User defined linear memory allocator

• WAMR_BUILD_ALLOC_WITH_USAGE=1/0, default to off.

• WAMR_BUILD_ALLOC_WITH_USER_DATA=1/0, default to off.

[!NOTE] By default, the system allocates linear memory. With this on and Alloc_With_Allocator selected, you can provide your own allocator.

running PGO(Profile-Guided Optimization) instrumented AOT file

• WAMR_BUILD_STATIC_PGO=1/0, default to off.

[!NOTE] See Use the AOT static PGO method.

linux perf support

• WAMR_BUILD_LINUX_PERF=1/0: enable linux perf support to generate flamegraphs for wasm app performance. Default is off.

[!NOTE] See Use linux-perf.

module instance context APIs

• WAMR_BUILD_MODULE_INST_CONTEXT=1/0: enable module instance context APIs so the embedder can set one or more contexts for a wasm module instance. Default is on.

    wasm_runtime_create_context_key
    wasm_runtime_destroy_context_key
    wasm_runtime_set_context
    wasm_runtime_set_context_spread
    wasm_runtime_get_context

[!NOTE] See wasm_export.h for details.

quick AOT/JTI entries

• WAMR_BUILD_QUICK_AOT_ENTRY=1/0: register quick call entries to speed up AOT/JIT function calls. Default is on.

[!NOTE] See Refine callings to AOT/JIT functions from host native.

AOT intrinsics

• WAMR_BUILD_AOT_INTRINSICS=1/0: turn on AOT intrinsic functions. Default is on. AOT code can call these when wamrc uses --disable-llvm-intrinsics or --enable-builtin-intrinsics=<intr1,intr2,...>.

[!NOTE] See Tuning the XIP intrinsic functions.

extended constant expression

• WAMR_BUILD_EXTENDED_CONST_EXPR=1/0, default to off.

[!NOTE] See Extended Constant Expressions.

bulk-memory-opt

• WAMR_BUILD_BULK_MEMORY_OPT=1/0, default to off.

[!NOTE] See bulk-memory-opt.

call-indirect-overlong

• WAMR_BUILD_CALL_INDIRECT_OVERLONG=1/0, default to off.

[!NOTE] See call-indirect-overlong.

Lime1 target

• WAMR_BUILD_LIME1=1/0, default to off.

[!NOTE] See Lime1.

Configurable memory access boundary check

• WAMR_CONFIGURABLE_BOUNDS_CHECKS=1/0, default to off.

[!WARNING] When enabled, you can run iwasm --disable-bounds-checks to turn off memory access boundary checks in interpreter mode. This is a privileged feature; use it carefully.

Shared heap among wasm apps and host native

• WAMR_BUILD_SHARED_HEAP=1/0, default to off.

[!NOTE] When enabled, you can create and attach shared heaps, and the following APIs become available:

   wasm_runtime_create_shared_heap
   wasm_runtime_attach_shared_heap
   wasm_runtime_detach_shared_heap
   wasm_runtime_shared_heap_malloc
   wasm_runtime_shared_heap_free

A wasm app can call these to use the shared heap attached to its module instance:

   void *shared_heap_malloc();
   void shared_heap_free(void *ptr);

[!WARNING] The shared-heap feature is not supported in fast-jit mode.

Shrunk the memory usage

• WAMR_BUILD_SHRUNK_MEMORY=1/0, default to on.

[!NOTE] When enabled, this reduces memory by shrinking linear memory, especially when memory.grow is unused and memory needs are predictable.

Instruction metering

• WAMR_BUILD_INSTRUCTION_METERING=1/0, default to off.

[!NOTE] This limits the number of instructions a wasm module instance can run. Call wasm_runtime_set_instruction_count_limit(...) before wasm_runtime_call_*(...) to enforce the cap.

[!WARNING] This is only supported in classic interpreter mode.

Invoke general FFI

• WAMR_BUILD_INVOKE_NATIVE_GENERAL=1/0, default to off.

By default, WAMR uses architecture-specific calling conventions to call native functions from WASM modules. When this feature is enabled, WAMR uses a general calling convention that works on all architectures but is slower. The details are in iwasm_common.cmake

Host defined log

• WAMR_BH_LOG=<log_callback>, default to off.

AOT Validator

• WAMR_BUILD_AOT_VALIDATOR=1/0, default to off.

[!NOTE] By default, WAMR believes AOT files are valid and unforged.

Copy Call Stack

• WAMR_BUILD_COPY_CALL_STACK=1/0, default to off.

[!NOTE] Unlike dump call stack, which prints the call stack on exceptions, this feature lets the embedder copy the call stack programmatically via wasm_runtime_dump_call_stack_to_buf().

Librats

• WAMR_BUILD_LIB_RATS=1/0, default to off.

librats is a C library designed to facilitate remote attestation for secure computing environments. It provides a framework for attesting the integrity of computing environments remotely, enabling trust establishment between different Trusted Execution Environments (TEEs).

[!WARNING] This is for Intel SGX platforms only.

Sanitizer

• WAMR_BUILD_SANITIZER=[ubsan|asan|tsan|posan], default is empty

Use one or more of the following sanitizers when building WAMR with sanitizer support: AddressSanitizer, UndefinedBehaviorSanitizer, ThreadSanitizer, or Pointer-Overflow Sanitizer.

Intel Protected File System

• WAMR_BUILD_SGX_IPFS=1/0, default to off.

[!WARNING] This is for Intel SGX platforms only.

Support spec test

• WAMR_BUILD_SPEC_TEST=1/0, default to off.

WASM Cache

• WAMR_BUILD_WASM_CACHE=1/0, default to off.

Test Garbage Collection

• WAMR_TEST_GC=1/0, default to off.

It is used to test garbage collection related APIs and features. Refer to iwasm_gc.cmake for details.

It is used to cache loaded wasm modules in memory to speed up module instantiation only in wasm-c-api.

Combination of configurations

You can mix settings. For example, to disable the interpreter, enable AOT and WASI, run:

cmake .. -DWAMR_BUILD_INTERP=0 -DWAMR_BUILD_AOT=1 -DWAMR_BUILD_LIBC_WASI=1 -DWAMR_BUILD_PLATFORM=linux

To enable the interpreter, disable AOT and WASI, and target X86_32, run:

cmake .. -DWAMR_BUILD_INTERP=1 -DWAMR_BUILD_AOT=0 -DWAMR_BUILD_LIBC_WASI=0 -DWAMR_BUILD_TARGET=X86_32

When enabling SIMD for fast interpreter mode, turn on both SIMD and the SIMDe library:

cmake .. -DWAMR_BUILD_INTERP=1 -DWAMR_BUILD_FAST_INTERP=1 -DWAMR_BUILD_SIMD=1 -DWAMR_BUILD_LIB_SIMDE=1

For Valgrind, start with these and add more as needed:

  #...
  -DCMAKE_BUILD_TYPE=Debug \
  -DWAMR_DISABLE_HW_BOUND_CHECK=0 \
  -DWAMR_DISABLE_WRITE_GS_BASE=0
  #...

To enable the minimal Lime1 feature set, turn off features that are on by default such as bulk memory and reference types:

cmake .. -DWAMR_BUILD_LIME1=1 -DWAMR_BUILD_BULK_MEMORY=0 -DWAMR_BUILD_REF_TYPES=0 -DDWAMR_BUILD_SIMD=0