libkrun · caxu-rh · Jun 4, 2026
@@ -0,0 +1,37 @@
+name: Build macOS kernel (experimental)
+on:
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  build:
+    name: Build aarch64 kernel on macOS
+    runs-on: macos-latest
+    steps:
+      - name: Code checkout
+        uses: actions/checkout@v6
+
+      - name: Create case-sensitive build volume
+        run: |
+          hdiutil create -size 8g -type SPARSE -fs "Case-sensitive APFS" -volname libkrunfw-cs "$RUNNER_TEMP/libkrunfw-cs.sparseimage"
+          hdiutil attach "$RUNNER_TEMP/libkrunfw-cs.sparseimage" -mountpoint "$RUNNER_TEMP/libkrunfw-cs" -nobrowse
+          rsync -a ./ "$RUNNER_TEMP/libkrunfw-cs/libkrunfw/"
+          echo "BUILD_DIR=$RUNNER_TEMP/libkrunfw-cs/libkrunfw" >> "$GITHUB_ENV"
+
+      - name: Install dependencies
+        run: |
+          brew install gnu-sed gnu-tar llvm lld make bc bison flex
+          python3 -m venv "${BUILD_DIR}/.venv"
+          source "${BUILD_DIR}/.venv/bin/activate"
+          pip3 install pyelftools
+
+      - name: Build libkrunfw
+        working-directory: ${{ env.BUILD_DIR }}
+        run: |
+          for pkg in gnu-sed gnu-tar; do
+            PATH="$(brew --prefix)/opt/${pkg}/libexec/gnubin:$PATH"
+          done
+          PATH="$(brew --prefix)/opt/llvm/bin:$PATH"
+          export PATH
+          source .venv/bin/activate
+          make MACOS_BUILDER=native
@@ -2,6 +2,7 @@ __pycache__
 *.pyc
 *~
 libkrunfw.so*
+libkrunfw.*.dylib
 kernel.c
 vmlinux
 /tarballs

@@ -13,6 +13,19 @@ KERNEL_FLAGS = KBUILD_BUILD_TIMESTAMP=$(TIMESTAMP)
 KERNEL_FLAGS += KBUILD_BUILD_USER=root
 KERNEL_FLAGS += KBUILD_BUILD_HOST=libkrunfw
 
+ifeq ($(origin OS),command line)
+    # Use the explicit OS value from command line (e.g. make OS=Windows)
+else
+    OS := $(shell uname -s)
+endif
+ifeq ($(OS),Darwin)
+    ifeq ($(origin MACOS_BUILDER),command line)
+        # Use the explicit MACOS_BUILDER value from command line (e.g. MACOS_BUILDER=native)
+    else
+        MACOS_BUILDER := krunvm
+    endif
+endif
+
 ifeq ($(SEV),1)
     VARIANT = -sev
     KERNEL_PATCHES += $(shell find patches-tee/ -name "0*.patch" | sort)
@@ -23,13 +36,13 @@ ifeq ($(TDX),1)
 endif
 
 HOSTARCH = $(shell uname -m)
-ifeq ($(origin OS),command line)
-    # Use the explicit OS value from command line (e.g. make OS=Windows)
-else
-    OS := $(shell uname -s)
-endif
 ifeq ($(ARCH),)
 	GUESTARCH := $(HOSTARCH)
+ifeq ($(OS),Darwin)
+ifeq ($(HOSTARCH),arm64)
+	GUESTARCH := aarch64
+endif
+endif
 	STRIP := strip
 else ifeq ($(ARCH),arm64)
 	GUESTARCH := aarch64
@@ -81,6 +94,30 @@ ifeq ($(PREFIX),)
     PREFIX := /usr/local
 endif
 
+ifeq ($(OS),Darwin)
+ifeq ($(MACOS_BUILDER),native)
+    # Native macOS kernel build tools (override on the make command line).
+    KERNEL_MAKE ?= gmake
+    KERNEL_CC ?= clang
+    KERNEL_LD ?= ld.lld
+    KERNEL_AR ?= llvm-ar
+    KERNEL_NM ?= llvm-nm
+    KERNEL_OBJCOPY ?= llvm-objcopy
+    KERNEL_OBJDUMP ?= llvm-objdump
+    KERNEL_STRIP ?= llvm-strip
+    KERNEL_READELF ?= llvm-readelf
+    KERNEL_HOSTCC ?= $(KERNEL_CC)
+
+    KERNEL_KBUILD_FLAGS = LLVM=1 ARCH=arm64 \
+        CC=$(KERNEL_CC) LD=$(KERNEL_LD) AR=$(KERNEL_AR) NM=$(KERNEL_NM) \
+        OBJCOPY=$(KERNEL_OBJCOPY) OBJDUMP=$(KERNEL_OBJDUMP) STRIP=$(KERNEL_STRIP) \
+        READELF=$(KERNEL_READELF) HOSTCC=$(KERNEL_HOSTCC) \
+        $(KERNEL_FLAGS)
+    MACOS_HOST_INCLUDE = $(CURDIR)/include/macos-host
+    KERNEL_HOSTFLAGS = HOSTCFLAGS="-I$(MACOS_HOST_INCLUDE) -D_UUID_T -D__GETHOSTUUID_H"
+endif
+endif
+
 ifeq ($(SEV),1)
     QBOOT_BINARY = qboot/sev/bios.bin
     QBOOT_C_BUNDLE = qboot.c
@@ -106,20 +143,42 @@ $(KERNEL_SOURCES): $(KERNEL_TARBALL)
 	tar xf $(KERNEL_TARBALL)
 	for patch in $(KERNEL_PATCHES); do patch -p1 -d $(KERNEL_SOURCES) < "$$patch"; done
 	cp config-libkrunfw$(VARIANT)_$(GUESTARCH) $(KERNEL_SOURCES)/.config
+ifeq ($(OS),Darwin)
+ifeq ($(MACOS_BUILDER),native)
+	cd $(KERNEL_SOURCES) && $(KERNEL_MAKE) $(KERNEL_KBUILD_FLAGS) $(KERNEL_HOSTFLAGS) olddefconfig
+else
+	cd $(KERNEL_SOURCES) ; $(MAKE) olddefconfig
+endif
+else
 	cd $(KERNEL_SOURCES) ; $(MAKE) olddefconfig
+endif
 
 $(KERNEL_BINARY_$(GUESTARCH)): $(KERNEL_SOURCES)
+ifeq ($(OS),Darwin)
+ifeq ($(MACOS_BUILDER),native)
+	cd $(KERNEL_SOURCES) && rm -f .version && $(KERNEL_MAKE) $(MAKEFLAGS) $(KERNEL_KBUILD_FLAGS) $(KERNEL_HOSTFLAGS)
+else
 	cd $(KERNEL_SOURCES) ; rm -f .version ; $(MAKE) $(MAKEFLAGS) $(KERNEL_FLAGS)
+endif
+else
+	cd $(KERNEL_SOURCES) ; rm -f .version ; $(MAKE) $(MAKEFLAGS) $(KERNEL_FLAGS)
+endif
 
 ifeq ($(OS),Darwin)
+ifeq ($(MACOS_BUILDER),krunvm)
 $(KERNEL_C_BUNDLE):
-	@echo "Building on macOS, using ./build_on_krunvm.sh"
+	@echo "Building on macOS using krunvm (./build_on_krunvm.sh)"
 	./build_on_krunvm.sh
 else
 $(KERNEL_C_BUNDLE): $(KERNEL_BINARY_$(GUESTARCH))
 	@echo "Generating $(KERNEL_C_BUNDLE) from $(KERNEL_BINARY_$(GUESTARCH))..."
 	@python3 bin2cbundle.py --os $(OS) -t $(KBUNDLE_TYPE_$(GUESTARCH)) $(KERNEL_BINARY_$(GUESTARCH)) kernel.c
 endif
+else
+$(KERNEL_C_BUNDLE): $(KERNEL_BINARY_$(GUESTARCH))
+	@echo "Generating $(KERNEL_C_BUNDLE) from $(KERNEL_BINARY_$(GUESTARCH))..."
+	@python3 bin2cbundle.py --os $(OS) -t $(KBUNDLE_TYPE_$(GUESTARCH)) $(KERNEL_BINARY_$(GUESTARCH)) kernel.c
+endif
 
 ifeq ($(SEV),1)
 $(QBOOT_C_BUNDLE): $(QBOOT_BINARY)

@@ -34,13 +34,12 @@ sudo make SEV=1 install
 
 ### macOS
 
-#### Requirements
+#### Building the library using krunvm
 
 Compiling a Linux kernel natively on macOS is not an easy feat. For this reason, the recommended way for building ```libkrunfw``` in this platform is by already having installed a binary version of [krunvm](https://github.com/containers/krunvm) and its dependencies ([libkrun](https://github.com/containers/libkrun), and ```libkrunfw``` itself), such as the one available in the [krunvm Homebrew repo](https://github.com/slp/homebrew-krun), and then executing the [build_on_krunvm.sh](build_on_krunvm.sh) script found in this repository.
 
 This will create a lightweight Linux VM using ```krunvm``` with the current working directory mapped inside it, and build the kernel on it.
 
-#### Building the library using krunvm
 ```
 ./build_on_krunvm.sh
 make
@@ -54,6 +53,30 @@ BUILDER=debian ./build_on_krunvm.sh
 
 In general, `./build_on_krunvm.sh` will always delegate to `./build_on_krunvm_${BUILDER}.sh` so additional environments can be added like this if needed.
 
+#### Building the library natively (experimental)
+
+The Linux kernel can be compiled natively on macOS. You will need some dependencies:
+* LLVM toolchain (`clang`, `lld`, etc.) (the version provided by Apple may not work)
+* GNU `make`
+* GNU `sed`
+* GNU `tar`
+* A case-sensitive file system
+
+The name of the `make`, `cc`, and some other executables can be overridden as arguments to the Makefile. If needed, you can also prepend to the `PATH` so that GNU versions of executables are chosen at higher priority.
+
+```
+# Create a case-sensitive disk image and mount it
+hdiutil create -size 8g -type SPARSE -fs "Case-sensitive APFS" -volname libkrunfw-cs ../libkrunfw-cs.sparseimage
+hdiutil attach ../libkrunfw-cs.sparseimage
+
+# Copy this source tree into the mounted disk image
+rsync -a ./ /Volumes/libkrunfw-cs/
+
+# Set up paths to the dependencies as needed, for example
+export PATH=/path/to/dir/containing/gnu/sed:/path/to/dir/containing/gnu/tar:$PATH
+make MACOS_BUILDER=native
+```
+
 ### Windows (cross-compilation from Linux)
 
 #### Requirements

@@ -0,0 +1,6 @@
+Vendored from https://github.com/bee-headers/headers.
+
+* elf.h — GNU Lesser General Public License v2.1 only (from GNU C Library)
+* endian.h, byteswap.h — GNU General Public License v2.0 only
+
+See the top-level LICENSE-GPL-2.0-only and LICENSE-LGPL-2.1-only files in this repository.
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _BYTESWAP_H
+#define _BYTESWAP_H 1
+
+#define bswap_16 __builtin_bswap16
+#define bswap_32 __builtin_bswap32
+#define bswap_64 __builtin_bswap64
+
+#endif /* _BYTESWAP_H */