init.c: port to FreeBSD, try to load json config from /dev/iso9660/KRUN_CONFIG

Makefile: add optional BSD build target

Signed-off-by: Jan Noha <nohajc@gmail.com>

Author: nohajc

.gitignore

@@ -17,3 +17,4 @@ examples/consoles
 examples/rootfs_fedora
 test-prefix
 /linux-sysroot
+/freebsd-sysroot

Makefile

@@ -55,11 +55,15 @@ ifeq ($(AWS_NITRO),1)
 	FEATURE_FLAGS := --features aws-nitro,net
 endif
 
+CLANG = /usr/bin/clang
+
 OS = $(shell uname -s)
 ARCH = $(shell uname -m)
 DEBIAN_DIST ?= bookworm
 ROOTFS_DIR = linux-sysroot
 GCC_VERSION ?= 12
+FREEBSD_VERSION ?= 14.3-RELEASE
+FREEBSD_ROOTFS_DIR = freebsd-sysroot
 
 KRUN_BINARY_Linux = libkrun$(VARIANT).so.$(FULL_VERSION)
 KRUN_SONAME_Linux = libkrun$(VARIANT).so.$(ABI_VERSION)
@@ -101,7 +105,7 @@ endif
     GCC_TRIPLET = $(subst arm64,aarch64,$(ARCH))-linux-gnu
     GCC_LIB_DIR = $(abspath $(SYSROOT_LINUX))/usr/lib/gcc/$(GCC_TRIPLET)/$(GCC_VERSION)
     # Cross-compile on macOS with the LLVM linker (brew install lld)
-    CC_LINUX=/usr/bin/clang -target $(GCC_TRIPLET) -fuse-ld=lld -Wl,-strip-debug --sysroot $(abspath $(SYSROOT_LINUX)) -B$(GCC_LIB_DIR) -L$(GCC_LIB_DIR) -Wno-c23-extensions
+    CC_LINUX=$(CLANG) -target $(GCC_TRIPLET) -fuse-ld=lld -Wl,-strip-debug --sysroot $(abspath $(SYSROOT_LINUX)) -B$(GCC_LIB_DIR) -L$(GCC_LIB_DIR) -Wno-c23-extensions
 else
     # Build on Linux host
     CC_LINUX=$(CC)
@@ -115,6 +119,28 @@ AWS_NITRO_INIT_BINARY= init/aws-nitro/init
 $(AWS_NITRO_INIT_BINARY): $(AWS_NITRO_INIT_SRC)
 	$(CC) -O2 -static -s -Wall $(AWS_NITRO_INIT_LD_FLAGS) -o $@ $(AWS_NITRO_INIT_SRC) $(AWS_NITRO_INIT_LD_FLAGS)
 
+ifeq ($(OS),Darwin)
+# If SYSROOT_BSD is not set and we're on macOS, generate sysroot automatically
+ifeq ($(SYSROOT_BSD),)
+    SYSROOT_BSD = $(FREEBSD_ROOTFS_DIR)
+    SYSROOT_BSD_TARGET = $(FREEBSD_ROOTFS_DIR)/.sysroot_ready
+else
+    SYSROOT_BSD_TARGET =
+endif
+    # Cross-compile on macOS with the LLVM linker (brew install lld)
+    CC_BSD=$(CLANG) -target $(ARCH)-unknown-freebsd -fuse-ld=lld -stdlib=libc++ -Wl,-strip-debug --sysroot $(SYSROOT_BSD)
+else
+    # Build on FreeBSD host
+    CC_BSD=$(CC)
+    SYSROOT_BSD_TARGET =
+endif
+
+ifeq ($(BUILD_BSD_INIT),1)
+INIT_BINARY_BSD = init/init-freebsd
+$(INIT_BINARY_BSD): $(INIT_SRC) $(SYSROOT_BSD_TARGET)
+	$(CC_BSD) -std=c23 -O2 -static -Wall $(INIT_DEFS) -lutil -o $@ $(INIT_SRC) $(INIT_DEFS)
+endif
+
 # Sysroot preparation rules for cross-compilation on macOS
 DEBIAN_PACKAGES = libc6 libc6-dev libgcc-$(GCC_VERSION)-dev linux-libc-dev
 ROOTFS_TMP = $(ROOTFS_DIR)/.tmp
@@ -143,11 +169,27 @@ $(PACKAGES_FILE):
 	@mkdir -p $(ROOTFS_TMP)
 	@curl -fL -o $@ https://deb.debian.org/debian/dists/$(DEBIAN_DIST)/main/binary-$(ARCH)/Packages.xz
 
+# FreeBSD sysroot preparation rules for cross-compilation on macOS
+FREEBSD_BASE_TXZ = $(FREEBSD_ROOTFS_DIR)/base.txz
+
+.INTERMEDIATE: $(FREEBSD_BASE_TXZ)
+
+$(FREEBSD_ROOTFS_DIR)/.sysroot_ready: $(FREEBSD_BASE_TXZ)
+	@echo "Extracting FreeBSD base to $(FREEBSD_ROOTFS_DIR)..."
+	@cd $(FREEBSD_ROOTFS_DIR) && tar xJf base.txz 2>/dev/null || true
+	@touch $@
+
+$(FREEBSD_BASE_TXZ):
+	@echo "Downloading FreeBSD $(FREEBSD_VERSION) base for $(ARCH)..."
+	@mkdir -p $(FREEBSD_ROOTFS_DIR)
+	@curl -fL -o $@ https://download.freebsd.org/releases/$(ARCH)/$(FREEBSD_VERSION)/base.txz
+
 clean-sysroot:
 	rm -rf $(ROOTFS_DIR)
+	rm -rf $(FREEBSD_ROOTFS_DIR)
 
 
-$(LIBRARY_RELEASE_$(OS)): $(SYSROOT_TARGET)
+$(LIBRARY_RELEASE_$(OS)): $(SYSROOT_TARGET) $(INIT_BINARY_BSD)
 	cargo build --release $(FEATURE_FLAGS)
 ifeq ($(SEV),1)
 	mv target/release/libkrun.so target/release/$(KRUN_BASE_$(OS))
@@ -166,7 +208,7 @@ endif
 endif
 	cp target/release/$(KRUN_BASE_$(OS)) $(LIBRARY_RELEASE_$(OS))
 
-$(LIBRARY_DEBUG_$(OS)): $(SYSROOT_TARGET)
+$(LIBRARY_DEBUG_$(OS)): $(SYSROOT_TARGET) $(INIT_BINARY_BSD)
 	cargo build $(FEATURE_FLAGS)
 ifeq ($(SEV),1)
 	mv target/debug/libkrun.so target/debug/$(KRUN_BASE_$(OS))
@@ -198,6 +240,9 @@ install: libkrun.pc
 	cd $(DESTDIR)$(PREFIX)/$(LIBDIR_$(OS))/ ; ln -sf $(KRUN_BINARY_$(OS)) $(KRUN_SONAME_$(OS)) ; ln -sf $(KRUN_SONAME_$(OS)) $(KRUN_BASE_$(OS))
 
 clean:
+ifeq ($(BUILD_BSD_INIT),1)
+	rm -f $(INIT_BINARY_BSD)
+endif
 	cargo clean
 	rm -rf test-prefix
 	cd tests; cargo clean