feat(boot): load separate x86 kernel image from UEFI bootloader

Makefile

@@ -1,12 +1,14 @@
 SHELL := /bin/bash
 
 CC := clang
+ELF_LD := ld.lld
 LD := lld-link
 ARCH ?= x86_64
 
 ifeq ($(ARCH),x86_64)
 ARCH_DIR := arch/x86
 EFI_ARCH_TARGET := x86_64-unknown-windows
+KERNEL_ARCH_TARGET := x86_64-unknown-none-elf
 BOOT_EFI_NAME := BOOTX64.EFI
 else
 $(error Unsupported ARCH '$(ARCH)')
@@ -16,6 +18,8 @@ BUILD_DIR := build
 EFI_DIR := $(BUILD_DIR)/image/EFI/BOOT
 BOOT_EFI := $(EFI_DIR)/$(BOOT_EFI_NAME)
 BOOT_OBJ := $(BUILD_DIR)/arch/boot/main.obj
+KERNEL_ELF := $(BUILD_DIR)/image/kernel.elf
+KERNEL_OBJS := $(BUILD_DIR)/arch/kernel/entry.o $(BUILD_DIR)/kernel/main.o
 DEBUG_LOG := $(BUILD_DIR)/debug.log
 OVMF_CODE ?= /usr/share/OVMF/OVMF_CODE_4M.fd
 OVMF_VARS_TEMPLATE ?= /usr/share/OVMF/OVMF_VARS_4M.fd
@@ -34,6 +38,23 @@ CFLAGS := \
 	-Iinclude \
 	-I$(ARCH_DIR)/include
 
+KERNEL_CFLAGS := \
+	-target $(KERNEL_ARCH_TARGET) \
+	-ffreestanding \
+	-fno-stack-protector \
+	-fno-builtin \
+	-fno-pic \
+	-mno-red-zone \
+	-Wall \
+	-Wextra \
+	-Werror \
+	-Iinclude \
+	-I$(ARCH_DIR)/include
+
+KERNEL_ASFLAGS := \
+	-target $(KERNEL_ARCH_TARGET) \
+	-ffreestanding
+
 LDFLAGS := \
 	/subsystem:efi_application \
 	/entry:efi_main \
@@ -42,19 +63,34 @@ LDFLAGS := \
 	/machine:x64 \
 	/out:$(BOOT_EFI)
 
+KERNEL_LDFLAGS := \
+	-m elf_x86_64 \
+	-nostdlib \
+	-T $(ARCH_DIR)/kernel/linker.ld \
+	-o $(KERNEL_ELF)
+
 .PHONY: all clean run run-headless dirs
 
-all: $(BOOT_EFI)
+all: $(BOOT_EFI) $(KERNEL_ELF)
 
 dirs:
-	mkdir -p $(BUILD_DIR)/arch/boot $(EFI_DIR)
+	mkdir -p $(BUILD_DIR)/arch/boot $(BUILD_DIR)/arch/kernel $(BUILD_DIR)/kernel $(EFI_DIR)
 
-$(BOOT_OBJ): $(ARCH_DIR)/boot/main.c $(ARCH_DIR)/include/efi.h include/tianole/boot_info.h | dirs
+$(BOOT_OBJ): $(ARCH_DIR)/boot/main.c $(ARCH_DIR)/include/efi.h include/tianole/boot_info.h include/tianole/elf.h | dirs
 	$(CC) $(CFLAGS) -c $< -o $@
 
 $(BOOT_EFI): $(BOOT_OBJ) | dirs
 	$(LD) $(LDFLAGS) $<
 
+$(BUILD_DIR)/arch/kernel/entry.o: $(ARCH_DIR)/kernel/entry.S | dirs
+	$(CC) $(KERNEL_ASFLAGS) -c $< -o $@
+
+$(BUILD_DIR)/kernel/main.o: kernel/main.c include/tianole/boot_info.h | dirs
+	$(CC) $(KERNEL_CFLAGS) -c $< -o $@
+
+$(KERNEL_ELF): $(KERNEL_OBJS) $(ARCH_DIR)/kernel/linker.ld | dirs
+	$(ELF_LD) $(KERNEL_LDFLAGS) $(KERNEL_OBJS)
+
 $(OVMF_VARS): | dirs
 	cp $(OVMF_VARS_TEMPLATE) $@
 

arch/x86/boot/main.c

@@ -1,16 +1,18 @@
 #include "efi.h"
+#include "tianole/elf.h"
 #include "tianole/boot_info.h"
 
-static efi_char16_t banner_text[] = {
+typedef void __attribute__((sysv_abi)) (*kernel_entry_fn_t)(const tianole_boot_info_t *);
+
+static efi_char16_t boot_banner_text[] = {
     'T', 'i', 'a', 'n', 'o', 'l', 'e', ' ',
     'x', '8', '6', ' ', 'b', 'o', 'o', 't',
-    ' ', 's', 't', 'u', 'b', ' ', 'l', 'o',
-    'a', 'd', 'e', 'd', '.', '\r', '\n', 0
+    'l', 'o', 'a', 'd', 'e', 'r', '.', '\r', '\n', 0
 };
 
-static const tianole_boot_info_t boot_info = {
-    .version = TIANOLE_BOOT_INFO_VERSION,
-    .boot_flags = 0,
+static efi_char16_t kernel_path_text[] = {
+    '\\', 'k', 'e', 'r', 'n', 'e', 'l', '.',
+    'e', 'l', 'f', 0
 };
 
 static inline void debug_putc(char ch) {
@@ -26,19 +28,240 @@ static void debug_puts(const char *text) {
     }
 }
 
-static void debug_boot_info(const tianole_boot_info_t *info) {
-    (void)info;
-    debug_puts("boot_info.version=1\n");
+static void *mem_copy(void *dst, const void *src, uint64_t size) {
+    uint8_t *out = (uint8_t *)dst;
+    const uint8_t *in = (const uint8_t *)src;
+    uint64_t i;
+
+    for (i = 0; i < size; ++i) {
+        out[i] = in[i];
+    }
+
+    return dst;
+}
+
+static void mem_zero(void *dst, uint64_t size) {
+    uint8_t *out = (uint8_t *)dst;
+    uint64_t i;
+
+    for (i = 0; i < size; ++i) {
+        out[i] = 0;
+    }
+}
+
+static efi_status open_root(
+    efi_handle image_handle,
+    efi_system_table_t *system_table,
+    efi_file_protocol_t **root
+) {
+    efi_guid_t loaded_image_guid = efi_loaded_image_protocol_guid();
+    efi_guid_t simple_fs_guid = efi_simple_file_system_protocol_guid();
+    efi_loaded_image_protocol_t *loaded_image;
+    efi_simple_file_system_protocol_t *fs;
+    efi_status status;
+
+    status = system_table->boot_services->handle_protocol(
+        image_handle,
+        &loaded_image_guid,
+        (void **)&loaded_image
+    );
+    if (status != EFI_SUCCESS) {
+        return status;
+    }
+
+    status = system_table->boot_services->handle_protocol(
+        loaded_image->device_handle,
+        &simple_fs_guid,
+        (void **)&fs
+    );
+    if (status != EFI_SUCCESS) {
+        return status;
+    }
+
+    return fs->open_volume(fs, root);
+}
+
+static efi_status read_entire_file(
+    efi_system_table_t *system_table,
+    efi_file_protocol_t *root,
+    efi_char16_t *path,
+    void **buffer,
+    uint64_t *size
+) {
+    efi_guid_t file_info_guid = efi_file_info_guid();
+    efi_file_protocol_t *file;
+    efi_file_info_t *file_info;
+    efi_uintn_t info_size;
+    efi_uintn_t read_size;
+    efi_status status;
+
+    status = root->open(root, &file, path, EFI_OPEN_MODE_READ, 0);
+    if (status != EFI_SUCCESS) {
+        return status;
+    }
+
+    info_size = 0;
+    status = file->get_info(file, &file_info_guid, &info_size, 0);
+    if (status != EFI_BUFFER_TOO_SMALL) {
+        file->close(file);
+        return status;
+    }
+
+    status = system_table->boot_services->allocate_pool(EFI_LOADER_DATA, info_size, (void **)&file_info);
+    if (status != EFI_SUCCESS) {
+        file->close(file);
+        return status;
+    }
+
+    status = file->get_info(file, &file_info_guid, &info_size, file_info);
+    if (status != EFI_SUCCESS) {
+        file->close(file);
+        return status;
+    }
+
+    *size = file_info->file_size;
+    status = system_table->boot_services->allocate_pool(EFI_LOADER_DATA, *size, buffer);
+    if (status != EFI_SUCCESS) {
+        file->close(file);
+        return status;
+    }
+
+    read_size = *size;
+    status = file->read(file, &read_size, *buffer);
+    file->close(file);
+    if (status != EFI_SUCCESS) {
+        return status;
+    }
+
+    if (read_size != *size) {
+        return EFI_LOAD_ERROR;
+    }
+
+    return EFI_SUCCESS;
+}
+
+static efi_status validate_kernel_elf(const elf64_ehdr_t *ehdr) {
+    if (*(const uint32_t *)ehdr->ident != ELF_MAGIC) {
+        return EFI_LOAD_ERROR;
+    }
+    if (ehdr->ident[4] != ELFCLASS64 || ehdr->ident[5] != ELFDATA2LSB) {
+        return EFI_LOAD_ERROR;
+    }
+    if (ehdr->ident[6] != EV_CURRENT || ehdr->version != EV_CURRENT) {
+        return EFI_LOAD_ERROR;
+    }
+    if (ehdr->type != ET_EXEC || ehdr->machine != EM_X86_64) {
+        return EFI_LOAD_ERROR;
+    }
+    if (ehdr->phentsize != sizeof(elf64_phdr_t)) {
+        return EFI_LOAD_ERROR;
+    }
+
+    return EFI_SUCCESS;
+}
+
+static efi_status load_kernel_image(
+    efi_system_table_t *system_table,
+    const void *kernel_image,
+    uint64_t kernel_size,
+    kernel_entry_fn_t *entry_out
+) {
+    const elf64_ehdr_t *ehdr = (const elf64_ehdr_t *)kernel_image;
+    const elf64_phdr_t *phdrs;
+    uint16_t index;
+    efi_status status;
+
+    if (kernel_size < sizeof(*ehdr)) {
+        return EFI_LOAD_ERROR;
+    }
+
+    status = validate_kernel_elf(ehdr);
+    if (status != EFI_SUCCESS) {
+        return status;
+    }
+
+    phdrs = (const elf64_phdr_t *)((const uint8_t *)kernel_image + ehdr->phoff);
+
+    for (index = 0; index < ehdr->phnum; ++index) {
+        const elf64_phdr_t *phdr = &phdrs[index];
+        efi_physical_address_t segment_base;
+        uint64_t page_count;
+
+        if (phdr->type != PT_LOAD) {
+            continue;
+        }
+
+        if (phdr->memsz < phdr->filesz) {
+            return EFI_LOAD_ERROR;
+        }
+        if (phdr->offset + phdr->filesz > kernel_size) {
+            return EFI_LOAD_ERROR;
+        }
+
+        segment_base = phdr->paddr;
+        page_count = (phdr->memsz + 0xfffULL) >> 12;
+        status = system_table->boot_services->allocate_pages(
+            EFI_ALLOCATE_ADDRESS,
+            EFI_LOADER_DATA,
+            page_count,
+            &segment_base
+        );
+        if (status != EFI_SUCCESS) {
+            return status;
+        }
+
+        mem_zero((void *)(uintptr_t)phdr->paddr, phdr->memsz);
+        mem_copy(
+            (void *)(uintptr_t)phdr->paddr,
+            (const uint8_t *)kernel_image + phdr->offset,
+            phdr->filesz
+        );
+    }
+
+    *entry_out = (kernel_entry_fn_t)(uintptr_t)ehdr->entry;
+    return EFI_SUCCESS;
 }
 
 efi_status EFIAPI efi_main(efi_handle image_handle, efi_system_table_t *system_table) {
-    (void)image_handle;
+    efi_file_protocol_t *root;
+    void *kernel_image;
+    uint64_t kernel_size;
+    kernel_entry_fn_t kernel_entry;
+    tianole_boot_info_t boot_info = {
+        .version = TIANOLE_BOOT_INFO_VERSION,
+        .boot_flags = TIANOLE_BOOT_FLAG_BOOT_SERVICES_ACTIVE,
+    };
+    efi_status status;
 
-    system_table->con_out->output_string(system_table->con_out, banner_text);
-    debug_puts("Tianole x86 boot stub loaded.\n");
-    debug_boot_info(&boot_info);
+    system_table->con_out->output_string(system_table->con_out, boot_banner_text);
+    debug_puts("Tianole x86 bootloader loaded.\n");
 
+    status = open_root(image_handle, system_table, &root);
+    if (status != EFI_SUCCESS) {
+        debug_puts("failed: open_root\n");
+        return status;
+    }
+
+    status = read_entire_file(system_table, root, kernel_path_text, &kernel_image, &kernel_size);
+    root->close(root);
+    if (status != EFI_SUCCESS) {
+        debug_puts("failed: read kernel.elf\n");
+        return status;
+    }
+
+    status = load_kernel_image(system_table, kernel_image, kernel_size, &kernel_entry);
+    if (status != EFI_SUCCESS) {
+        debug_puts("failed: load kernel image\n");
+        return status;
+    }
+
+    debug_puts("jumping to kernel entry\n");
+    kernel_entry(&boot_info);
+
+    debug_puts("kernel returned unexpectedly\n");
     for (;;) {
         system_table->boot_services->stall(1000 * 1000);
     }
+
+    return EFI_SUCCESS;
 }

arch/x86/include/efi.h

@@ -7,8 +7,28 @@ typedef uint64_t efi_status;
 typedef void *efi_handle;
 typedef uint16_t efi_char16_t;
 typedef uint64_t efi_uintn_t;
+typedef uint64_t efi_physical_address_t;
 
 #define EFI_SUCCESS 0
+#define EFI_LOAD_ERROR 0x8000000000000001ULL
+#define EFI_INVALID_PARAMETER 0x8000000000000002ULL
+#define EFI_BUFFER_TOO_SMALL 0x8000000000000005ULL
+#define EFI_OUT_OF_RESOURCES 0x8000000000000009ULL
+#define EFI_NOT_FOUND 0x800000000000000eULL
+
+#define EFI_ALLOCATE_ADDRESS 2
+#define EFI_LOADER_DATA 4
+#define EFI_OPEN_MODE_READ 0x0000000000000001ULL
+
+#define EFI_FILE_INFO_ID 0x09576e92
+#define EFI_FILE_INFO_ID_A 0x6d3f
+#define EFI_FILE_INFO_ID_B 0x11d2
+#define EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_GUID_A 0x964e5b22
+#define EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_GUID_B 0x6459
+#define EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_GUID_C 0x11d2
+#define EFI_LOADED_IMAGE_PROTOCOL_GUID_A 0x5b1b31a1
+#define EFI_LOADED_IMAGE_PROTOCOL_GUID_B 0x9562
+#define EFI_LOADED_IMAGE_PROTOCOL_GUID_C 0x11d2
 
 #if defined(__x86_64__)
 #define EFIAPI __attribute__((ms_abi))
@@ -16,6 +36,13 @@ typedef uint64_t efi_uintn_t;
 #define EFIAPI
 #endif
 
+typedef struct {
+    uint32_t data1;
+    uint16_t data2;
+    uint16_t data3;
+    uint8_t data4[8];
+} efi_guid_t;
+
 typedef struct {
     uint64_t signature;
     uint32_t revision;
@@ -26,6 +53,10 @@ typedef struct {
 
 typedef struct efi_simple_text_output_protocol efi_simple_text_output_protocol_t;
 typedef struct efi_boot_services efi_boot_services_t;
+typedef struct efi_simple_file_system_protocol efi_simple_file_system_protocol_t;
+typedef struct efi_file_protocol efi_file_protocol_t;
+typedef struct efi_loaded_image_protocol efi_loaded_image_protocol_t;
+typedef struct efi_system_table efi_system_table_t;
 
 struct efi_simple_text_output_protocol {
     void *reset;
@@ -35,14 +66,87 @@ struct efi_simple_text_output_protocol {
     );
 };
 
+typedef struct {
+    uint64_t size;
+    uint64_t file_size;
+    uint64_t physical_size;
+    uint64_t create_time[2];
+    uint64_t last_access_time[2];
+    uint64_t modification_time[2];
+    uint64_t attribute;
+    efi_char16_t file_name[1];
+} efi_file_info_t;
+
+struct efi_file_protocol {
+    uint64_t revision;
+    efi_status(EFIAPI *open)(
+        efi_file_protocol_t *self,
+        efi_file_protocol_t **new_handle,
+        efi_char16_t *file_name,
+        uint64_t open_mode,
+        uint64_t attributes
+    );
+    efi_status(EFIAPI *close)(efi_file_protocol_t *self);
+    void *delete_;
+    efi_status(EFIAPI *read)(
+        efi_file_protocol_t *self,
+        efi_uintn_t *buffer_size,
+        void *buffer
+    );
+    void *write;
+    void *get_position;
+    void *set_position;
+    efi_status(EFIAPI *get_info)(
+        efi_file_protocol_t *self,
+        efi_guid_t *information_type,
+        efi_uintn_t *buffer_size,
+        void *buffer
+    );
+    void *set_info;
+    void *flush;
+};
+
+struct efi_simple_file_system_protocol {
+    uint64_t revision;
+    efi_status(EFIAPI *open_volume)(
+        efi_simple_file_system_protocol_t *self,
+        efi_file_protocol_t **root
+    );
+};
+
+struct efi_loaded_image_protocol {
+    uint32_t revision;
+    efi_handle parent_handle;
+    efi_system_table_t *system_table;
+    efi_handle device_handle;
+    void *file_path;
+    void *reserved;
+    uint32_t load_options_size;
+    void *load_options;
+    void *image_base;
+    uint64_t image_size;
+    uint32_t image_code_type;
+    uint32_t image_data_type;
+    void *unload;
+};
+
 struct efi_boot_services {
     efi_table_header_t hdr;
     void *raise_tpl;
     void *restore_tpl;
-    void *allocate_pages;
+    efi_status(EFIAPI *allocate_pages)(
+        int type,
+        int memory_type,
+        efi_uintn_t pages,
+        efi_physical_address_t *memory
+    );
     void *free_pages;
     void *get_memory_map;
-    void *allocate_pool;
+    efi_status(EFIAPI *allocate_pool)(
+        int pool_type,
+        efi_uintn_t size,
+        void **buffer
+    );
     void *free_pool;
     void *create_event;
     void *set_timer;
@@ -53,7 +157,11 @@ struct efi_boot_services {
     void *install_protocol_interface;
     void *reinstall_protocol_interface;
     void *uninstall_protocol_interface;
-    void *handle_protocol;
+    efi_status(EFIAPI *handle_protocol)(
+        efi_handle handle,
+        efi_guid_t *protocol,
+        void **interface
+    );
     void *reserved;
     void *register_protocol_notify;
     void *locate_handle;
@@ -69,7 +177,7 @@ struct efi_boot_services {
     void *set_watchdog_timer;
 };
 
-typedef struct {
+struct efi_system_table {
     efi_table_header_t hdr;
     efi_char16_t *firmware_vendor;
     uint32_t firmware_revision;
@@ -83,6 +191,33 @@ typedef struct {
     efi_boot_services_t *boot_services;
     uint64_t number_of_table_entries;
     void *configuration_table;
-} efi_system_table_t;
+};
+
+static inline efi_guid_t efi_file_info_guid(void) {
+    return (efi_guid_t){
+        .data1 = EFI_FILE_INFO_ID,
+        .data2 = EFI_FILE_INFO_ID_A,
+        .data3 = EFI_FILE_INFO_ID_B,
+        .data4 = {0x8e, 0x39, 0x00, 0xa0, 0xc9, 0x69, 0x72, 0x3b},
+    };
+}
+
+static inline efi_guid_t efi_simple_file_system_protocol_guid(void) {
+    return (efi_guid_t){
+        .data1 = EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_GUID_A,
+        .data2 = EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_GUID_B,
+        .data3 = EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_GUID_C,
+        .data4 = {0x8e, 0x39, 0x00, 0xa0, 0xc9, 0x69, 0x72, 0x3b},
+    };
+}
+
+static inline efi_guid_t efi_loaded_image_protocol_guid(void) {
+    return (efi_guid_t){
+        .data1 = EFI_LOADED_IMAGE_PROTOCOL_GUID_A,
+        .data2 = EFI_LOADED_IMAGE_PROTOCOL_GUID_B,
+        .data3 = EFI_LOADED_IMAGE_PROTOCOL_GUID_C,
+        .data4 = {0x8e, 0x3f, 0x00, 0xa0, 0xc9, 0x69, 0x72, 0x3b},
+    };
+}
 
 #endif

arch/x86/kernel/entry.S

@@ -0,0 +1,17 @@
+.global _start
+.type _start, @function
+
+.section .text
+_start:
+    lea kernel_stack_top(%rip), %rsp
+    call kernel_main
+
+1:
+    hlt
+    jmp 1b
+
+.section .bss
+.balign 16
+kernel_stack:
+    .skip 16384
+kernel_stack_top:

arch/x86/kernel/linker.ld

@@ -0,0 +1,23 @@
+ENTRY(_start)
+
+SECTIONS
+{
+    . = 0x200000;
+
+    .text : ALIGN(4K) {
+        *(.text .text.*)
+    }
+
+    .rodata : ALIGN(4K) {
+        *(.rodata .rodata.*)
+    }
+
+    .data : ALIGN(4K) {
+        *(.data .data.*)
+    }
+
+    .bss : ALIGN(4K) {
+        *(COMMON)
+        *(.bss .bss.*)
+    }
+}

docs/roadmap.md

@@ -149,6 +149,12 @@
 - 屏幕和 `debug.log` 有可见输出
 - 程序可常驻，便于调试
 
+当前已经开始进入第 1 阶段：
+
+- 代码结构已经为 `bootloader -> kernel` 交接预留边界
+- `boot_info` 已经作为项目自有交接结构存在
+- `arch/x86/` 已经承载当前架构专用启动代码
+
 当前还没有完成：
 
 - 独立 `kernel` 接管

include/tianole/boot_info.h

@@ -14,5 +14,6 @@ typedef struct {
 } tianole_boot_info_t;
 
 #define TIANOLE_BOOT_INFO_VERSION 1u
+#define TIANOLE_BOOT_FLAG_BOOT_SERVICES_ACTIVE (1u << 0)
 
 #endif

include/tianole/elf.h

@@ -0,0 +1,44 @@
+#ifndef TIANOLE_ELF_H
+#define TIANOLE_ELF_H
+
+#include <stdint.h>
+
+#define ELF_MAGIC 0x464c457fu
+#define ELFCLASS64 2
+#define ELFDATA2LSB 1
+#define EV_CURRENT 1
+
+#define ET_EXEC 2
+#define EM_X86_64 62
+
+#define PT_LOAD 1
+
+typedef struct {
+    unsigned char ident[16];
+    uint16_t type;
+    uint16_t machine;
+    uint32_t version;
+    uint64_t entry;
+    uint64_t phoff;
+    uint64_t shoff;
+    uint32_t flags;
+    uint16_t ehsize;
+    uint16_t phentsize;
+    uint16_t phnum;
+    uint16_t shentsize;
+    uint16_t shnum;
+    uint16_t shstrndx;
+} elf64_ehdr_t;
+
+typedef struct {
+    uint32_t type;
+    uint32_t flags;
+    uint64_t offset;
+    uint64_t vaddr;
+    uint64_t paddr;
+    uint64_t filesz;
+    uint64_t memsz;
+    uint64_t align;
+} elf64_phdr_t;
+
+#endif

kernel/main.c

@@ -1,4 +1,33 @@
-/*
- * Kernel code starts in the next stage.
- * The initial milestone is a verified UEFI boot path.
- */
+#include <stdint.h>
+
+#include "tianole/boot_info.h"
+
+static inline void debug_putc(char ch) {
+    __asm__ volatile("outb %0, $0xe9" : : "a"(ch));
+}
+
+static void debug_puts(const char *text) {
+    while (*text != '\0') {
+        if (*text == '\n') {
+            debug_putc('\r');
+        }
+        debug_putc(*text++);
+    }
+}
+
+void kernel_main(const tianole_boot_info_t *boot_info) {
+    debug_puts("kernel_main entered\n");
+    if (boot_info != 0 && boot_info->version == TIANOLE_BOOT_INFO_VERSION) {
+        debug_puts("boot_info.version ok\n");
+    } else {
+        debug_puts("boot_info.version invalid\n");
+    }
+
+    if (boot_info != 0 && (boot_info->boot_flags & TIANOLE_BOOT_FLAG_BOOT_SERVICES_ACTIVE) != 0) {
+        debug_puts("boot services still active\n");
+    }
+
+    for (;;) {
+        __asm__ volatile("hlt");
+    }
+}