[BOOT] Parse multiboot information

kernel/boot/boot.S

@@ -1,6 +1,13 @@
 .intel_syntax noprefix
 #include <mem.h>
 
+.section .data
+// Some room to store the bootloader return values
+MultiBootMagic:
+  .quad 0x0
+MultiBootData:
+  .quad 0x0
+
 // Some info from here: http://os.phil-opp.com/multiboot-kernel.html
 .section .text
 .global _start
@@ -8,6 +15,9 @@
 _start:
   cli
 
+  // Save eax and ebx in memory
+  mov V2P(MultiBootMagic), eax
+  mov V2P(MultiBootData), ebx
 
   // Check if long mode is available
   // Otherwise, there's no point in continuing
@@ -74,6 +84,12 @@ long_mode_start:
   mov rax, 0x0
   mov [V2P(BootP4)], rax
 
+  // Get the saved bootloader data and pass to kmain
+  movabs rax, MultiBootMagic
+  mov rdi, rax
+  movabs rax, MultiBootData
+  mov rsi, rax
+
   // Call c kernel code
   .extern kmain
   call kmain

kernel/boot/kmain.c

@@ -1,21 +1,14 @@
 #include <debug.h>
+#include <multiboot.h>
+#include <mem.h>
 
-int kmain(void)
+int kmain(uint64_t multiboot_magic, void *multiboot_data)
 {
   debug_init();
   debug_ok("MITTOS64 kernel booted\n");
   debug_build_time();
   debug_git_info();
-
-  // Test the printf functions
-  debug("binary:%b octal:%o dec:%d\n", 0xAA55, 0123, 456);
-  debug("hex:%x string:%s char:%c\n", 0xabcd, "Hello", 'T');
-  debug("pointer:%x\n", kmain);
-
-  debug_info("An information string\n");
-  debug_ok("%s prints ok\n", "This string");
-  debug_warning("A warning message\n");
-  debug_error("%d is less than %x\n", 12, 17);
+  multiboot_init(multiboot_magic, P2V(multiboot_data));
 
   debug_info("BOOT COMPLETE\n");
   for(;;)asm("hlt");

kernel/boot/multiboot.c

@@ -0,0 +1,94 @@
+#include <stdint.h>
+#include <multiboot.h>
+#include <mem.h>
+#include <debug.h>
+
+struct mboot_data_st mboot_data;
+
+
+void parse_multiboot1()
+{
+  mboot1_info *data = mboot_data.data;
+  if(data->flags & (1<<2))
+  {
+    debug_ok("MBOOT1 - commandline\n");
+    mboot_data.commandline = P2V(data->cmdline);
+  }
+  if(data->flags & (1<<9))
+  {
+    debug_ok("MBOOT1 - bootloader\n");
+    mboot_data.bootloader = P2V(data->bootloader_name);
+  }
+}
+
+char *mboot_tags_type[] = {
+  "", // 0
+  "Boot command line", // 1
+  "Boot loader name", // 2
+  "Module", // 3
+  "Basic memory information", // 4
+  "BIOS Boot device", // 5
+  "Memory map", // 6
+  "VBE info", // 7
+  "Framebuffer info", // 8
+  "ELF-Symbols", //9
+  "APM table", // 10
+  "EFI 32-bit system table pointer", // 11
+  "EFI 64-bit system table pointer", // 12
+  "SMBIOS tables", // 13
+  "ACPI old RSDP", // 14
+  "ACPI new RSDP", // 15
+  "Networking information", // 16
+  "EFI memory map", // 17
+  "EFI boot services not terminated",
+};
+void parse_multiboot2()
+{
+  mboot2_tags_head *data = mboot_data.data;
+  mboot2_tag_basic *tag = (void *)(data + 1);
+  while(tag->type != 0)
+  {
+    switch(tag->type)
+    {
+      case MBOOT2_CMDLINE:
+        mboot_data.commandline = tag->data;
+        debug_ok("MBOOT2 - handle ");
+        break;
+      case MBOOT2_BOOTLOADER:
+        mboot_data.bootloader = tag->data;
+        debug_ok("MBOOT2 - handle ");
+        break;
+      default:
+        debug_warning("MBOOT2 - ignore ");
+        break;
+    }
+    if(tag->type <= 18)
+      debug("%s (%d bytes)\n", mboot_tags_type[tag->type], tag->size);
+    else
+      debug("Unknown tag: %d (%d bytes)\n", tag->type, tag->size);
+    tag = next_tag(tag);
+  }
+}
+
+void multiboot_init(uint64_t magic, void *data)
+{
+  mboot_data.data = data;
+  debug_info("MBOOT - Magic:%x\n", magic);
+  if(magic == MBOOT1_MAGIC2)
+  {
+    debug_info("MBOOT - Multiboot version 1\n");
+    mboot_data.version = 1;
+    parse_multiboot1();
+  } else if (magic == MBOOT2_MAGIC2) {
+    debug_info("MBOOT - Multiboot version 2\n");
+    mboot_data.version = 2;
+    parse_multiboot2();
+  } else {
+    debug_error("PANIC - NOT A MULTIBOOT COMPLIANT BOOTLOADER\n");
+    for(;;);
+  }
+  if(mboot_data.commandline)
+    debug_info("MBOOT - Command line: %s\n", mboot_data.commandline);
+  if(mboot_data.bootloader)
+    debug_info("MBOOT - Bootloader: %s\n", mboot_data.bootloader);
+}

kernel/include/mem.h

@@ -13,6 +13,8 @@
   #include <stdint.h>
   #define V2P(a) ((uintptr_t)(a) - KERNEL_OFFSET)
   #define P2V(a) ((void *)((uintptr_t)(a) + KERNEL_OFFSET))
+  // returns an address n bytes after the target of pointer p
+  #define incptr(p, n) ((void *)(((uintptr_t)(p)) + (n)))
 #endif
 
 // Paging

kernel/include/multiboot.h

@@ -12,3 +12,66 @@
 #define MBOOT2_LENGTH (MultiBootHeaderEnd - MultiBootHeader)
 #define MBOOT2_CHECKSUM -(MBOOT2_MAGIC + MBOOT2_ARCH + MBOOT2_LENGTH)
 
+#ifndef __ASSEMBLER__
+#include <stdint.h>
+
+// MULTIBOOT 1
+  typedef struct {
+    uint32_t flags;
+    uint32_t mem_lower;
+    uint32_t mem_upper;
+    uint32_t boot_device;
+    uint32_t cmdline;
+    uint32_t mods_count;
+    uint32_t mods_addr;
+    uint32_t symbol_num;
+    uint32_t symbol_size;
+    uint32_t symbol_addr;
+    uint32_t symbol_shndx;
+    uint32_t mmap_len;
+    uint32_t mmap_addr;
+    uint32_t drives_len;
+    uint32_t drives_addr;
+    uint32_t config_table;
+    uint32_t bootloader_name;
+    uint32_t apm_table;
+    uint32_t vbe_control_info;
+    uint32_t vbe_mode_info;
+    uint32_t vbe_mode;
+    uint32_t vbe_interface_seg;
+    uint32_t vbe_interface_off;
+    uint32_t vbe_interface_len;
+  } mboot1_info;
+
+// MULTIBOOT 2
+
+  typedef struct {
+    uint32_t total_size;
+    uint32_t reserved;
+  } mboot2_tags_head;
+
+  typedef struct {
+    uint32_t type;
+    uint32_t size;
+    char data[];
+  } mboot2_tag_basic;
+
+
+  #define MBOOT2_CMDLINE 1
+  #define MBOOT2_BOOTLOADER 2
+
+  // Multiboot tags are padded to a multiple of 8 bytes
+  #define next_tag(tag) ((void *)((((uintptr_t)tag) + tag->size + 7) & ~0x7))
+
+  extern char *mboot_tags_type[];
+  struct mboot_data_st{
+    int version;
+    void *data;
+    char *commandline;
+    char *bootloader;
+  };
+  extern struct mboot_data_st mboot_data;
+
+  void multiboot_init(uint64_t magic, void *data);
+
+#endif