[PATCH for-xen-4.5 v4 18/18] xen/x86: add multiboot2 protocol support

[Daniel Kiper <daniel.kiper@oracle.com>]

Add multiboot2 protocol support. Alter min memory limit handling as we
now may not find it from either multiboot (v1) or multiboot2.

This way we are laying the foundation for EFI + GRUB2 + Xen development.

Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
---
v4 - suggestions/fixes:
   - use macro to get multiboot2 data
     (suggested by Jan Beulich),
   - use named constant in assembly files
     (suggested by Andrew Cooper),
   - rearrange condition for multiboot protocol version
     detection; fallback to multiboot(1) if protocol
     is unknown
     (suggested by Andrew Cooper),
   - improve multiboot2 header comment in head.S
     (suggested by Jan Beulich).

v3 - suggestions/fixes:
   - rearrange assembly a bit
     (suggested by Andrew Cooper),
   - define only used structs in multiboot2.h
     (suggested by Andrew Cooper),
   - improve commit comment
     (suggested by Andrew Cooper),
   - further patch split rearrangement
     (suggested by Andrew Cooper).

v2 - suggestions/fixes:
   - use "for" instead of "while" for loops
     (suggested by Jan Beulich),
   - properly parenthesize macro arguments
     (suggested by Jan Beulich),
   - change some local variables types
     (suggested by Jan Beulich),
   - use meaningful labels
     (suggested by Andrew Cooper and Jan Beulich),
   - use local labels
     (suggested by Jan Beulich),
   - fix coding style
     (suggested by Jan Beulich),
   - patch split rearrangement
     (suggested by Andrew Cooper and Jan Beulich).
---
 xen/arch/x86/boot/Makefile        |    3 +-
 xen/arch/x86/boot/head.S          |  132 ++++++++++++++++++++++++++++++--
 xen/arch/x86/boot/reloc.c         |  119 ++++++++++++++++++++++++++++-
 xen/arch/x86/x86_64/asm-offsets.c |    6 ++
 xen/include/xen/multiboot2.h      |  153 +++++++++++++++++++++++++++++++++++++
 5 files changed, 401 insertions(+), 12 deletions(-)
 create mode 100644 xen/include/xen/multiboot2.h

diff --git a/xen/arch/x86/boot/Makefile b/xen/arch/x86/boot/Makefile
index e6ff2b7..031a758 100644
--- a/xen/arch/x86/boot/Makefile
+++ b/xen/arch/x86/boot/Makefile
@@ -1,7 +1,8 @@
 obj-bin-y += head.o
 
 RELOC_DEPS = $(BASEDIR)/include/asm-x86/config.h $(BASEDIR)/include/xen/compiler.h \
-	     $(BASEDIR)/include/xen/multiboot.h $(BASEDIR)/include/asm-x86/mbd.h
+	     $(BASEDIR)/include/xen/multiboot.h $(BASEDIR)/include/xen/multiboot2.h \
+	     $(BASEDIR)/include/asm-x86/mbd.h
 
 export RELOC_DEPS
 
diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index 12e41f9..e9a5955 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -1,5 +1,6 @@
 #include <xen/config.h>
 #include <xen/multiboot.h>
+#include <xen/multiboot2.h>
 #include <public/xen.h>
 #include <asm/asm_defns.h>
 #include <asm/desc.h>
@@ -33,6 +34,82 @@ ENTRY(start)
         /* Checksum: must be the negated sum of the first two fields. */
         .long   -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS)
 
+/*** MULTIBOOT2 HEADER ****/
+/* Some ideas are taken from grub-2.00/grub-core/tests/boot/kernel-i386.S file. */
+        .align  MULTIBOOT2_HEADER_ALIGN
+
+.Lmultiboot2_header:
+        /* Magic number indicating a Multiboot2 header. */
+        .long   MULTIBOOT2_HEADER_MAGIC
+        /* Architecture: i386. */
+        .long   MULTIBOOT2_ARCHITECTURE_I386
+        /* Multiboot2 header length. */
+        .long   .Lmultiboot2_header_end - .Lmultiboot2_header
+        /* Multiboot2 header checksum. */
+        .long   -(MULTIBOOT2_HEADER_MAGIC + MULTIBOOT2_ARCHITECTURE_I386 + \
+                        (.Lmultiboot2_header_end - .Lmultiboot2_header))
+
+        /* Multiboot2 tags... */
+.Lmultiboot2_info_req:
+        /* Multiboot2 information request tag. */
+        .short  MULTIBOOT2_HEADER_TAG_INFORMATION_REQUEST
+        .short  MULTIBOOT2_HEADER_TAG_REQUIRED
+        .long   .Lmultiboot2_info_req_end - .Lmultiboot2_info_req
+        .long   MULTIBOOT2_TAG_TYPE_MMAP
+.Lmultiboot2_info_req_end:
+
+        /*
+         * Align Xen image and modules at page boundry.
+         *
+         * .balignl MULTIBOOT2_TAG_ALIGN, MULTIBOOT2_TAG_TYPE_END is a hack
+         * to avoid bug related to Multiboot2 information request tag in earlier
+         * versions of GRUB2.
+         *
+         * DO NOT MOVE THIS TAG! ANY CHANGE HERE MAY BREAK COMPATIBILITY
+         * WITH EARLIER GRUB2 VERSIONS!
+         *
+         * Earlier versions of GRUB2 incorrectly calculate Multiboot2 information
+         * request tag size and read past the end of it 8 bytes. It means that
+         * these 8 bytes must contain something valid in terms of request tag.
+         * Fortunately next tag has MULTIBOOT2_TAG_TYPE_MMAP meaning as a request
+         * and as is it does not change anything in our request because we asked
+         * for that thing above. However, if request tag ends at unaligned address
+         * and .align is used then compiler may put random value in void before
+         * first tag. This could not be accepted by earlier versions of GRUB2 and
+         * Xen load would fail. So, use .balignl and forcibly fill this void with
+         * something valid in terms of request tag. However, this thing should not
+         * change our request in significant way. MULTIBOOT2_TAG_TYPE_END satisfies
+         * these assumptions because GRUB2 must provide ending tag for list of
+         * arguments even if it was not explicitly requested.
+         */
+        .balignl MULTIBOOT2_TAG_ALIGN, MULTIBOOT2_TAG_TYPE_END
+        .short   MULTIBOOT2_HEADER_TAG_MODULE_ALIGN
+        .short   MULTIBOOT2_HEADER_TAG_REQUIRED
+        .long    8 /* Tag size. */
+
+        /* Console flags tag. */
+        .align  MULTIBOOT2_TAG_ALIGN
+        .short  MULTIBOOT2_HEADER_TAG_CONSOLE_FLAGS
+        .short  MULTIBOOT2_HEADER_TAG_OPTIONAL
+        .long   12 /* Tag size. */
+        .long   MULTIBOOT2_CONSOLE_FLAGS_EGA_TEXT_SUPPORTED
+
+        /* Framebuffer tag. */
+        .align  MULTIBOOT2_TAG_ALIGN
+        .short  MULTIBOOT2_HEADER_TAG_FRAMEBUFFER
+        .short  MULTIBOOT2_HEADER_TAG_OPTIONAL
+        .long   20 /* Tag size. */
+        .long   0 /* Number of the columns - no preference. */
+        .long   0 /* Number of the lines - no preference. */
+        .long   0 /* Number of bits per pixel - no preference. */
+
+        /* Multiboot2 header end tag. */
+        .align  MULTIBOOT2_TAG_ALIGN
+        .short  MULTIBOOT2_HEADER_TAG_END
+        .short  0
+        .long   8 /* Tag size. */
+.Lmultiboot2_header_end:
+
         .section .init.rodata, "a", @progbits
         .align 4
 
@@ -81,10 +158,54 @@ __start:
         mov     %ecx,%es
         mov     %ecx,%ss
 
+        /* Assume multiboot[12].mem_lower is 0 if not set by bootloader */
+        xor     %edx,%edx
+
         /* Check for Multiboot bootloader */
         cmp     $MULTIBOOT_BOOTLOADER_MAGIC,%eax
-        jne     not_multiboot
+        je      multiboot_proto
+
+        /* Check for Multiboot2 bootloader */
+        cmp     $MULTIBOOT2_BOOTLOADER_MAGIC,%eax
+        je      multiboot2_proto
+
+        jmp     not_multiboot
+
+multiboot_proto:
+        /* Get mem_lower from Multiboot information */
+        testb   $MBI_MEMLIMITS,(%ebx)
+        jz      trampoline_setup    /* not available? BDA value will be fine */
+
+        mov     MBI_mem_lower(%ebx),%edx
+        jmp     trampoline_setup
+
+multiboot2_proto:
+        /* Get Multiboot2 information address */
+        mov     %ebx,%ecx
+
+        /* Skip Multiboot2 information fixed part */
+        add     $MBI2_fixed_sizeof,%ecx
+
+0:
+        /* Get mem_lower from Multiboot2 information */
+        cmpl    $MULTIBOOT2_TAG_TYPE_BASIC_MEMINFO,(%ecx)
+        jne     1f
+
+        mov     MBI2_mem_lower(%ecx),%edx
+        jmp     trampoline_setup
 
+1:
+        /* Is it the end of Multiboot2 information? */
+        cmpl    $MULTIBOOT2_TAG_TYPE_END,(%ecx)
+        je      trampoline_setup
+
+        /* Go to next Multiboot2 information tag */
+        add     MBI2_tag_size(%ecx),%ecx
+        add     $(MULTIBOOT2_TAG_ALIGN-1),%ecx
+        and     $~(MULTIBOOT2_TAG_ALIGN-1),%ecx
+        jmp     0b
+
+trampoline_setup:
         /* Set up trampoline segment 64k below EBDA */
         movzwl  0x40e,%ecx          /* EBDA segment */
         cmp     $0xa000,%ecx        /* sanity check (high) */
@@ -99,9 +220,6 @@ __start:
          * Compare the value in the BDA with the information from the
          * multiboot structure (if available) and use the smallest.
          */
-        testb   $MBI_MEMLIMITS,(%ebx)
-        jz      2f                  /* not available? BDA value will be fine */
-        mov     MBI_mem_lower(%ebx),%edx
         cmp     $0x100,%edx         /* is the multiboot value too small? */
         jb      2f                  /* if so, do not use it */
         shl     $10-4,%edx
@@ -116,11 +234,11 @@ __start:
         shl     $4, %ecx
         mov     %ecx,sym_phys(trampoline_phys)
 
-        /* Save the Multiboot info struct (after relocation) for later use. */
+        /* Save the Multiboot data (after relocation) for later use. */
         mov     $sym_phys(cpu0_stack)+1024,%esp
-        mov     %ecx,%eax
+        push    %eax                /* Multiboot magic */
         push    %ebx                /* Multiboot information address */
-        call    reloc               /* %eax contains trampoline address */
+        call    reloc               /* %ecx contains trampoline address */
         mov     %eax,sym_phys(mbd_pa)
 
         /* Initialize BSS (no nasty surprises!) */
diff --git a/xen/arch/x86/boot/reloc.c b/xen/arch/x86/boot/reloc.c
index 9792fcd..4984b00 100644
--- a/xen/arch/x86/boot/reloc.c
+++ b/xen/arch/x86/boot/reloc.c
@@ -5,19 +5,26 @@
  * and modules. This is most easily done early with paging disabled.
  *
  * Copyright (c) 2009, Citrix Systems, Inc.
+ * Copyright (c) 2013, 2014 Oracle Corp.
  *
  * Authors:
  *    Keir Fraser <keir@xen.org>
+ *    Daniel Kiper
  */
 
-/* entered with %eax = BOOT_TRAMPOLINE */
+/*
+ * This entry point is entered from xen/arch/x86/boot/head.S with:
+ *   - %eax = MULTIBOOT_MAGIC,
+ *   - %ebx = MULTIBOOT_INFORMATION_ADDRESS,
+ *   - %ecx = BOOT_TRAMPOLINE.
+ */
 asm (
     "    .text                         \n"
     "    .globl _start                 \n"
     "_start:                           \n"
     "    call 1f                       \n"
     "1:  pop  %ebx                     \n"
-    "    mov  %eax,alloc-1b(%ebx)      \n"
+    "    mov  %ecx,alloc-1b(%ebx)      \n"
     "    jmp  reloc                    \n"
     );
 
@@ -31,12 +38,19 @@ asm (
     );
 
 typedef unsigned int u32;
+typedef unsigned long long u64;
 
 #include "../../../include/xen/compiler.h"
 #include "../../../include/xen/multiboot.h"
+#include "../../../include/xen/multiboot2.h"
 
 #include "../../../include/asm/mbd.h"
 
+#define ALIGN_UP(addr, align) \
+                (((addr) + (typeof(addr))(align) - 1) & ~((typeof(addr))(align) - 1))
+
+#define get_mb2_data(tag, type, member) (((type *)(tag))->member)
+
 static u32 alloc_struct(u32 bytes)
 {
     u32 s;
@@ -127,12 +141,109 @@ static mbd_t *mb_mbd(mbd_t *mbd, multiboot_info_t *mbi)
     return mbd;
 }
 
-static mbd_t __used *reloc(void *mbi)
+static mbd_t *mb2_mbd(mbd_t *mbd, void *mbi)
+{
+    boot_module_t *mbd_mods;
+    memory_map_t *mmap_dst;
+    multiboot2_memory_map_t *mmap_src;
+    multiboot2_tag_t *tag;
+    u32 ptr;
+    unsigned int i, mod_idx = 0;
+
+    /* Skip Multiboot2 information fixed part. */
+    tag = mbi + sizeof(multiboot2_fixed_t);
+
+    for ( ; ; )
+    {
+        if ( tag->type == MULTIBOOT2_TAG_TYPE_MODULE )
+            ++mbd->mods_nr;
+        else if ( tag->type == MULTIBOOT2_TAG_TYPE_END )
+        {
+            mbd->mods = alloc_struct(mbd->mods_nr * sizeof(boot_module_t));
+            mbd_mods = (boot_module_t *)mbd->mods;
+            break;
+        }
+
+        /* Go to next Multiboot2 information tag. */
+        tag = (multiboot2_tag_t *)(ALIGN_UP((u32)tag + tag->size, MULTIBOOT2_TAG_ALIGN));
+    }
+
+    /* Skip Multiboot2 information fixed part. */
+    tag = mbi + sizeof(multiboot2_fixed_t);
+
+    for ( ; ; )
+    {
+        switch ( tag->type )
+        {
+        case MULTIBOOT2_TAG_TYPE_BOOT_LOADER_NAME:
+            ptr = (u32)get_mb2_data(tag, multiboot2_tag_string_t, string);
+            mbd->boot_loader_name = copy_string(ptr);
+            break;
+
+        case MULTIBOOT2_TAG_TYPE_CMDLINE:
+            ptr = (u32)get_mb2_data(tag, multiboot2_tag_string_t, string);
+            mbd->cmdline = copy_string(ptr);
+            break;
+
+        case MULTIBOOT2_TAG_TYPE_BASIC_MEMINFO:
+            mbd->mem_lower = get_mb2_data(tag, multiboot2_tag_basic_meminfo_t, mem_lower);
+            mbd->mem_upper = get_mb2_data(tag, multiboot2_tag_basic_meminfo_t, mem_upper);
+            break;
+
+        case MULTIBOOT2_TAG_TYPE_MMAP:
+            mbd->mmap_size = get_mb2_data(tag, multiboot2_tag_mmap_t, size);
+            mbd->mmap_size -= sizeof(multiboot2_tag_mmap_t);
+            mbd->mmap_size += sizeof(((multiboot2_tag_mmap_t){0}).entries);
+            mbd->mmap_size /= get_mb2_data(tag, multiboot2_tag_mmap_t, entry_size);
+            mbd->mmap_size *= sizeof(memory_map_t);
+
+            mbd->mmap = alloc_struct(mbd->mmap_size);
+
+            mmap_src = get_mb2_data(tag, multiboot2_tag_mmap_t, entries);
+            mmap_dst = (memory_map_t *)mbd->mmap;
+
+            for ( i = 0; i < mbd->mmap_size / sizeof(memory_map_t); ++i )
+            {
+                mmap_dst[i].size = sizeof(memory_map_t);
+                mmap_dst[i].size -= sizeof(((memory_map_t){0}).size);
+                mmap_dst[i].base_addr_low = (u32)mmap_src[i].addr;
+                mmap_dst[i].base_addr_high = (u32)(mmap_src[i].addr >> 32);
+                mmap_dst[i].length_low = (u32)mmap_src[i].len;
+                mmap_dst[i].length_high = (u32)(mmap_src[i].len >> 32);
+                mmap_dst[i].type = mmap_src[i].type;
+            }
+            break;
+
+        case MULTIBOOT2_TAG_TYPE_MODULE:
+            mbd_mods[mod_idx].start = get_mb2_data(tag, multiboot2_tag_module_t, mod_start);
+            mbd_mods[mod_idx].end = get_mb2_data(tag, multiboot2_tag_module_t, mod_end);
+            ptr = (u32)get_mb2_data(tag, multiboot2_tag_module_t, cmdline);
+            mbd_mods[mod_idx].cmdline = copy_string(ptr);
+            mbd_mods[mod_idx].relocated = 0;
+            ++mod_idx;
+            break;
+
+        case MULTIBOOT2_TAG_TYPE_END:
+            return mbd;
+
+        default:
+            break;
+        }
+
+        /* Go to next Multiboot2 information tag. */
+        tag = (multiboot2_tag_t *)(ALIGN_UP((u32)tag + tag->size, MULTIBOOT2_TAG_ALIGN));
+    }
+}
+
+static mbd_t __used *reloc(void *mbi, u32 mb_magic)
 {
     mbd_t *mbd;
 
     mbd = (mbd_t *)alloc_struct(sizeof(*mbd));
     zero_struct((u32)mbd, sizeof(*mbd));
 
-    return mb_mbd(mbd, mbi);
+    if ( mb_magic == MULTIBOOT2_BOOTLOADER_MAGIC )
+        return mb2_mbd(mbd, mbi);
+    else
+        return mb_mbd(mbd, mbi);
 }
diff --git a/xen/arch/x86/x86_64/asm-offsets.c b/xen/arch/x86/x86_64/asm-offsets.c
index 7364dd6..ac4ce93 100644
--- a/xen/arch/x86/x86_64/asm-offsets.c
+++ b/xen/arch/x86/x86_64/asm-offsets.c
@@ -10,6 +10,7 @@
 #include <xen/sched.h>
 #include <xen/bitops.h>
 #include <xen/multiboot.h>
+#include <xen/multiboot2.h>
 #include <compat/xen.h>
 #include <asm/fixmap.h>
 #include <asm/hardirq.h>
@@ -167,5 +168,10 @@ void __dummy__(void)
     OFFSET(MBI_mem_lower, multiboot_info_t, mem_lower);
     BLANK();
 
+    DEFINE(MBI2_fixed_sizeof, sizeof(multiboot2_fixed_t));
+    OFFSET(MBI2_tag_size, multiboot2_tag_t, size);
+    OFFSET(MBI2_mem_lower, multiboot2_tag_basic_meminfo_t, mem_lower);
+    BLANK();
+
     OFFSET(MBD_cmdline, mbd_t, cmdline);
 }
diff --git a/xen/include/xen/multiboot2.h b/xen/include/xen/multiboot2.h
new file mode 100644
index 0000000..95eaa76
--- /dev/null
+++ b/xen/include/xen/multiboot2.h
@@ -0,0 +1,153 @@
+/*
+ *  Copyright (C) 1999,2003,2007,2008,2009,2010  Free Software Foundation, Inc.
+ *
+ *  multiboot2.h - Multiboot 2 header file.
+ *
+ *  Based on grub-2.00/include/multiboot2.h file.
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy
+ *  of this software and associated documentation files (the "Software"), to
+ *  deal in the Software without restriction, including without limitation the
+ *  rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ *  sell copies of the Software, and to permit persons to whom the Software is
+ *  furnished to do so, subject to the following conditions:
+ *
+ *  The above copyright notice and this permission notice shall be included in
+ *  all copies or substantial portions of the Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL ANY
+ *  DEVELOPER OR DISTRIBUTOR BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ *  WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+ *  IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef __MULTIBOOT2_H__
+#define __MULTIBOOT2_H__
+
+/* The magic field should contain this.  */
+#define MULTIBOOT2_HEADER_MAGIC			0xe85250d6
+
+/* This should be in %eax on x86 architecture.  */
+#define MULTIBOOT2_BOOTLOADER_MAGIC		0x36d76289
+
+/* How many bytes from the start of the file we search for the header.  */
+#define MULTIBOOT2_SEARCH			32768
+
+/* Multiboot 2 header alignment. */
+#define MULTIBOOT2_HEADER_ALIGN			8
+
+/* Alignment of multiboot 2 modules.  */
+#define MULTIBOOT2_MOD_ALIGN			0x00001000
+
+/* Alignment of the multiboot 2 info structure.  */
+#define MULTIBOOT2_INFO_ALIGN			0x00000008
+
+/* Multiboot 2 architectures. */
+#define MULTIBOOT2_ARCHITECTURE_I386	0
+#define MULTIBOOT2_ARCHITECTURE_MIPS32	4
+
+/* Header tag types. */
+#define MULTIBOOT2_HEADER_TAG_END			0
+#define MULTIBOOT2_HEADER_TAG_INFORMATION_REQUEST	1
+#define MULTIBOOT2_HEADER_TAG_ADDRESS			2
+#define MULTIBOOT2_HEADER_TAG_ENTRY_ADDRESS		3
+#define MULTIBOOT2_HEADER_TAG_CONSOLE_FLAGS		4
+#define MULTIBOOT2_HEADER_TAG_FRAMEBUFFER		5
+#define MULTIBOOT2_HEADER_TAG_MODULE_ALIGN		6
+#define MULTIBOOT2_HEADER_TAG_EFI_BS			7
+
+/* Header tag flags. */
+#define MULTIBOOT2_HEADER_TAG_REQUIRED	0
+#define MULTIBOOT2_HEADER_TAG_OPTIONAL	1
+
+/* Header console tag console_flags. */
+#define MULTIBOOT2_CONSOLE_FLAGS_CONSOLE_REQUIRED	1
+#define MULTIBOOT2_CONSOLE_FLAGS_EGA_TEXT_SUPPORTED	2
+
+/* Flags set in the 'flags' member of the multiboot header.  */
+#define MULTIBOOT2_TAG_TYPE_END			0
+#define MULTIBOOT2_TAG_TYPE_CMDLINE		1
+#define MULTIBOOT2_TAG_TYPE_BOOT_LOADER_NAME	2
+#define MULTIBOOT2_TAG_TYPE_MODULE		3
+#define MULTIBOOT2_TAG_TYPE_BASIC_MEMINFO	4
+#define MULTIBOOT2_TAG_TYPE_BOOTDEV		5
+#define MULTIBOOT2_TAG_TYPE_MMAP		6
+#define MULTIBOOT2_TAG_TYPE_VBE			7
+#define MULTIBOOT2_TAG_TYPE_FRAMEBUFFER		8
+#define MULTIBOOT2_TAG_TYPE_ELF_SECTIONS	9
+#define MULTIBOOT2_TAG_TYPE_APM			10
+#define MULTIBOOT2_TAG_TYPE_EFI32		11
+#define MULTIBOOT2_TAG_TYPE_EFI64		12
+#define MULTIBOOT2_TAG_TYPE_SMBIOS		13
+#define MULTIBOOT2_TAG_TYPE_ACPI_OLD		14
+#define MULTIBOOT2_TAG_TYPE_ACPI_NEW		15
+#define MULTIBOOT2_TAG_TYPE_NETWORK		16
+#define MULTIBOOT2_TAG_TYPE_EFI_MMAP		17
+#define MULTIBOOT2_TAG_TYPE_EFI_BS		18
+
+/* Multiboot 2 tag alignment. */
+#define MULTIBOOT2_TAG_ALIGN			8
+
+/* Memory types. */
+#define MULTIBOOT2_MEMORY_AVAILABLE		1
+#define MULTIBOOT2_MEMORY_RESERVED		2
+#define MULTIBOOT2_MEMORY_ACPI_RECLAIMABLE	3
+#define MULTIBOOT2_MEMORY_NVS			4
+#define MULTIBOOT2_MEMORY_BADRAM		5
+
+/* Framebuffer types. */
+#define MULTIBOOT2_FRAMEBUFFER_TYPE_INDEXED	0
+#define MULTIBOOT2_FRAMEBUFFER_TYPE_RGB		1
+#define MULTIBOOT2_FRAMEBUFFER_TYPE_EGA_TEXT	2
+
+#ifndef __ASSEMBLY__
+typedef struct {
+    u32 total_size;
+    u32 reserved;
+} multiboot2_fixed_t;
+
+typedef struct {
+    u32 type;
+    u32 size;
+} multiboot2_tag_t;
+
+typedef struct {
+    u32 type;
+    u32 size;
+    char string[0];
+} multiboot2_tag_string_t;
+
+typedef struct {
+    u32 type;
+    u32 size;
+    u32 mem_lower;
+    u32 mem_upper;
+} multiboot2_tag_basic_meminfo_t;
+
+typedef struct __packed {
+    u64 addr;
+    u64 len;
+    u32 type;
+    u32 zero;
+} multiboot2_memory_map_t;
+
+typedef struct {
+    u32 type;
+    u32 size;
+    u32 entry_size;
+    u32 entry_version;
+    multiboot2_memory_map_t entries[0];
+} multiboot2_tag_mmap_t;
+
+typedef struct {
+    u32 type;
+    u32 size;
+    u32 mod_start;
+    u32 mod_end;
+    char cmdline[0];
+} multiboot2_tag_module_t;
+#endif /* __ASSEMBLY__ */
+
+#endif /* __MULTIBOOT2_H__ */
-- 
1.7.10.4