Initial commit

.gitignore

@@ -0,0 +1,7 @@
+.zig-cache
+zig-cache
+zig-out
+
+*.efi
+*.pdb
+*.img

Makefile

@@ -0,0 +1,76 @@
+IMG_FILE := bootable.img
+IMG_SIZE_MB := 100
+EFI_FILE := bootx64.efi
+MNT_DIR := esp_mnt
+USB_DEV ?= /dev/sdX
+
+.PHONY: all clean flash
+
+# The default target, which is to build the image file.
+all: $(EFI_FILE)
+	@echo "--- Creating blank disk image: $(IMG_FILE) ($(IMG_SIZE_MB)MB)..."
+	dd if=/dev/zero of=$(IMG_FILE) bs=1M count=$(IMG_SIZE_MB) status=none
+
+	sudo -v
+
+	@echo "--- Creating GPT and EFI System Partition..."
+	# Use sgdisk for non-interactive partitioning.
+	# --new=1:0:0 creates partition 1, starting at the first available sector and filling the disk.
+	# --typecode=1:ef00 sets the partition type to 'EFI System'.
+	sudo sgdisk --new=1:0:0 --typecode=1:ef00 $(IMG_FILE)
+
+	@# This block handles setting up, using, and cleaning up a loop device and mount point.
+	@# 'set -e' ensures the script will exit immediately if a command fails.
+	@# The trap command guarantees that we unmount the partition and detach the loop device on exit,
+	@# even if an error occurs.
+	set -e; \
+	LOOP_DEV=$$(sudo losetup --partscan --show --find $(IMG_FILE)); \
+	trap 'echo "--- Cleaning up mount point and loop device..."; sudo umount $(MNT_DIR) 2>/dev/null || true; sudo losetup -d $$LOOP_DEV 2>/dev/null || true; rm -rf $(MNT_DIR);' EXIT; \
+	\
+	echo "--- Using loop device: $$LOOP_DEV"; \
+	echo "--- Formatting EFI partition (FAT32)..."; \
+	sudo mkfs.vfat -F32 $${LOOP_DEV}p1; \
+	\
+	echo "--- Mounting partition..."; \
+	mkdir -p $(MNT_DIR); \
+	sudo mount $${LOOP_DEV}p1 $(MNT_DIR); \
+	\
+	echo "--- Copying EFI executable to EFI/BOOT/BOOTX64.EFI..."; \
+	sudo mkdir -p $(MNT_DIR)/EFI/BOOT; \
+	sudo cp $(EFI_FILE) $(MNT_DIR)/EFI/BOOT/BOOTX64.EFI; \
+	\
+	echo "--- Syncing filesystem..."; \
+	sync;
+
+	@echo "\nSuccess! Bootable image created: $(IMG_FILE)"
+
+$(EFI_FILE):
+	zig build-exe -OReleaseFast -target x86_64-uefi-msvc --name bootx64 main.zig
+
+# Rule to flash the image to a USB device.
+flash: $(IMG_FILE)
+	@if [ "$(USB_DEV)" = "/dev/sdX" ]; then \
+		echo "\nERROR: USB_DEV is not set."; \
+		echo "Please specify the target device, e.g., 'make flash USB_DEV=/dev/sdb'"; \
+		exit 1; \
+	fi
+	@echo "\n!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"
+	@echo "!! WARNING: This will ERASE ALL DATA on $(USB_DEV) !!"
+	@echo "!! Verify that this is the correct device before proceeding.   !!"
+	@echo "!! Press Ctrl+C to cancel, or Enter to continue.             !!"
+	@echo "!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"
+	@read
+	sudo dd if=$(IMG_FILE) of=$(USB_DEV) bs=4M status=progress conv=fsync
+
+# Rule to clean up all generated files and temporary directories.
+clean:
+	@echo "--- Cleaning up..."
+	@-sudo umount $(MNT_DIR) >/dev/null 2>&1 || true
+	@-rm -rf $(MNT_DIR)
+	@-if losetup -j $(IMG_FILE) > /dev/null 2>&1; then \
+		LOOP_DEV=$$(losetup -j $(IMG_FILE) | cut -d: -f1); \
+		echo "Detaching loop device $$LOOP_DEV..."; \
+		sudo losetup -d $$LOOP_DEV; \
+	fi
+	@-rm -f $(IMG_FILE)
+	@echo "Cleanup complete."

build.sh

@@ -0,0 +1,57 @@
+#!/bin/bash
+set -e
+
+# This script creates a bootable EFI image file
+# It replicates the logic from the 'all' target of the Makefile
+
+IMG_FILE="bootable.img"
+IMG_SIZE_MB=100
+EFI_FILE="bootx64.efi"
+MNT_DIR="esp_mnt"
+
+# Make sure we have sudo privileges
+sudo -v
+
+echo ">>> Checking for source file: ${EFI_FILE}..."
+if [ ! -f "${EFI_FILE}" ]; then
+    echo "Error: Source file '${EFI_FILE}' not found."
+    echo "Please place your EFI executable in this directory."
+    exit 1
+fi
+
+echo ">>> Creating blank disk image: ${IMG_FILE} (${IMG_SIZE_MB}MB)..."
+dd if=/dev/zero of="${IMG_FILE}" bs=1M count=${IMG_SIZE_MB} status=none
+
+echo ">>> Creating GPT and EFI System Partition..."
+sudo sgdisk --new=1:0:0 --typecode=1:ef00 "${IMG_FILE}"
+
+# Set up a trap to ensure cleanup happens even if the script fails
+cleanup() {
+    echo ">>> Cleaning up..."
+    # The '|| true' prevents the script from exiting if umount fails (e.g., not mounted)
+    sudo umount "${MNT_DIR}" 2>/dev/null || true
+    if [ -n "${LOOP_DEV}" ]; then
+        sudo losetup -d "${LOOP_DEV}" 2>/dev/null || true
+    fi
+    rm -rf "${MNT_DIR}"
+}
+
+trap cleanup EXIT
+
+echo ">>> Setting up loop device..."
+LOOP_DEV=$(sudo losetup --partscan --show --find "${IMG_FILE}")
+echo ">>> Using loop device: ${LOOP_DEV}"
+
+echo ">>> Formatting EFI partition (FAT32)..."
+sudo mkfs.vfat -F32 "${LOOP_DEV}p1"
+
+echo ">>> Mounting partition..."
+mkdir -p "${MNT_DIR}"
+sudo mount "${LOOP_DEV}p1" "${MNT_DIR}"
+
+echo ">>> Copying EFI executable to EFI/BOOT/BOOTX64.EFI..."
+sudo mkdir -p "${MNT_DIR}/EFI/BOOT"
+sudo cp "${EFI_FILE}" "${MNT_DIR}/EFI/BOOT/BOOTX64.EFI"
+
+echo ">>> Syncing filesystem..."
+sync

build.zig

@@ -0,0 +1,20 @@
+const std = @import("std");
+
+pub fn build(b: *std.Build) void {
+    const uefi_target = b.resolveTargetQuery(.{
+        .cpu_arch = .x86_64,
+        .os_tag = .uefi,
+        .abi = .msvc,
+    });
+
+    const exe = b.addExecutable(.{
+        .name = "bootx64.efi",
+        .root_module = b.createModule(.{
+            .root_source_file = b.path("main.zig"),
+            .optimize = .ReleaseFast,
+            .target = uefi_target,
+        }),
+    });
+
+    b.default_step.dependOn(&exe.step);
+}

justfile

@@ -0,0 +1,56 @@
+#!/usr/bin/env just --justfile
+
+IMG_FILE    := 'small.img'
+IMG_SIZE_MB := '36'
+EFI_NAME    := 'bootx64'
+EFI_FILE    := 'bootx64.efi'
+MNT_DIR     := 'esp_mnt'
+
+default: image
+
+build:
+    @echo ">>> Building UEFI executable ({{EFI_FILE}})..."
+    zig build-exe -OReleaseFast -target x86_64-uefi-msvc --name {{EFI_NAME}} main.zig
+
+_image-init:
+    echo ">>> Creating blank disk image: {{IMG_FILE}} ({{IMG_SIZE_MB}}MB)..."
+    #dd if=/dev/zero of={{IMG_FILE}} bs=1M count={{IMG_SIZE_MB}}
+    fallocate -l {{IMG_SIZE_MB}}M {{IMG_FILE}}
+
+    sudo -v
+
+    echo ">>> Creating GPT and EFI System Partition..."
+    sudo sgdisk --new=1:0:0 --typecode=1:ef00 {{IMG_FILE}}
+
+image: build _image-init
+    #!/usr/bin/env bash
+    set -euo pipefail
+
+    LOOP_DEV=$(sudo losetup --partscan --show --find {{IMG_FILE}})
+    trap 'sudo umount {{MNT_DIR}} 2>/dev/null || true; sudo losetup -d "$LOOP_DEV" 2>/dev/null || true; rm -rf {{MNT_DIR}};' EXIT
+
+    echo ">>> Using loop device: $LOOP_DEV"
+    echo ">>> Formatting EFI partition (FAT32)..."
+    sudo mkfs.vfat -F32 "${LOOP_DEV}p1"
+
+    echo ">>> Mounting partition..."
+    mkdir -p {{MNT_DIR}}
+    sudo mount "${LOOP_DEV}p1" {{MNT_DIR}}
+
+    echo ">>> Copying EFI executable to EFI/BOOT/BOOTX64.EFI..."
+    sudo mkdir -p {{MNT_DIR}}/EFI/BOOT
+    sudo cp {{EFI_FILE}} {{MNT_DIR}}/EFI/BOOT/BOOTX64.EFI
+
+    echo ">>> Syncing filesystem..."
+    sync
+
+    echo "Success! Bootable image created: {{IMG_FILE}}"
+
+run: image
+    qemu-system-x86_64 -bios /usr/share/ovmf/OVMF.fd -drive format=raw,file={{IMG_FILE}}
+
+clean:
+    @echo ">>> Cleaning up..."
+    -rm -vrf zig-cache zig-out
+    -rm -vf *.img bootx64*
+    @echo ">>> Cleanup complete."

main.zig

@@ -0,0 +1,13 @@
+const std = @import("std");
+const uefi = std.os.uefi;
+
+const W = std.unicode.utf8ToUtf16LeStringLiteral;
+
+pub fn main() void {
+    const con_out = uefi.system_table.con_out.?;
+    con_out.reset(false) catch unreachable;
+    _ = con_out.outputString(W("Hi :D\r\n")) catch unreachable;
+
+    const boot_services = uefi.system_table.boot_services.?;
+    boot_services.stall(5 * 1000 * 1000) catch unreachable;
+}