Let's try to start parsing ELFs!

.gitignore

@@ -5,3 +5,5 @@ toolchain/
 initrd/boot/moon.elf
 kernel/bin/moon.elf
 initrd/sys/moon.sym
+initrd/bin/**
+apps/bin/**

Makefile

@@ -1,10 +1,12 @@
-build: $(LUNA_ROOT)/kernel/bin/moon.elf
+build: $(LUNA_ROOT)/kernel/bin/moon.elf apps-build
 
-clean: moon-clean initrd-clean
+clean: moon-clean initrd-clean apps-clean
 
 initrd-clean:
 	rm -f $(LUNA_ROOT)/initrd/boot/moon.elf $(LUNA_ROOT)/Luna.iso
+	rm -rf $(LUNA_ROOT)/initrd/bin
 
-install: $(LUNA_ROOT)/initrd/boot/moon.elf
+install: $(LUNA_ROOT)/initrd/boot/moon.elf apps-install
 
 include kernel/Makefile
+include apps/Makefile

apps/Makefile

@@ -0,0 +1,31 @@
+APPS := init
+
+APPS_DIR := $(LUNA_ROOT)/apps
+APPS_OBJ := $(APPS_DIR)/lib
+APPS_BIN := $(APPS_DIR)/bin
+
+REAL_APPS := $(patsubst %, $(APPS_BIN)/%, $(APPS))
+
+ASMC := nasm
+ASMFLAGS := -felf64
+
+LD := x86_64-elf-ld
+APP_LDFLAGS := -T$(APPS_DIR)/apps.ld -nostdlib
+
+$(APPS_OBJ)/%.o: $(APPS_DIR)/%.asm
+	@mkdir -p $(@D)
+	$(ASMC) $(ASMFLAGS) -o $@ $^
+
+$(APPS_BIN)/%: $(APPS_OBJ)/%.o
+	@mkdir -p $(@D)
+	$(LD) $(APP_LDFLAGS) -o $@ $^
+
+apps-build: $(REAL_APPS)
+
+apps-install: $(REAL_APPS)
+	@mkdir -p $(LUNA_ROOT)/initrd/bin
+	cp $(REAL_APPS) $(LUNA_ROOT)/initrd/bin
+
+apps-clean:
+	rm -f $(APPS_OBJ)/*
+	rm -f $(APPS_BIN)/*

apps/apps.ld

@@ -0,0 +1,21 @@
+ENTRY(_start)
+OUTPUT_FORMAT(elf64-x86-64)
+
+SECTIONS
+{
+    . = 0x10000;
+    .text : ALIGN(16) {
+        KEEP(*(.text.boot)) *(.text .text.*)   /* code */
+        *(.rodata .rodata.*)                   /* data */
+    }
+    .data : ALIGN(16) {
+        *(.data .data.*)
+    }
+    .bss (NOLOAD) : {                          /* bss */
+        . = ALIGN(16);
+        *(.bss .bss.*)
+        *(COMMON)
+    }
+
+    /DISCARD/ : { *(.eh_frame) *(.comment) }
+}

apps/init.asm

@@ -0,0 +1,5 @@
+section .text
+global _start
+_start:
+    mov rax, 0
+    int 42h