Re: [PATCH 04/18] xen/x86: add multiboot2 protocol support

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 30/01/15 17:54, Daniel Kiper wrote:
> 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>

I have not reviewed the multiboot2 protocol in detail, but it appears
sane and I presume it is suitably tested and works.

As far as the mb1/mb2 interaction goes, this is looking far better.

Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

> ---
>  xen/arch/x86/boot/Makefile        |    3 +-
>  xen/arch/x86/boot/head.S          |  104 ++++++++++++++++++++--
>  xen/arch/x86/boot/reloc.c         |  174 ++++++++++++++++++++++++++++++++-----
>  xen/arch/x86/x86_64/asm-offsets.c |    6 ++
>  xen/include/xen/multiboot2.h      |  169 +++++++++++++++++++++++++++++++++++
>  5 files changed, 429 insertions(+), 27 deletions(-)
>  create mode 100644 xen/include/xen/multiboot2.h
>
> diff --git a/xen/arch/x86/boot/Makefile b/xen/arch/x86/boot/Makefile
> index 5fdb5ae..0efa7d2 100644
> --- a/xen/arch/x86/boot/Makefile
> +++ b/xen/arch/x86/boot/Makefile
> @@ -1,6 +1,7 @@
>  obj-bin-y += head.o
>  
> -RELOC_DEPS = $(BASEDIR)/include/asm-x86/config.h $(BASEDIR)/include/xen/multiboot.h
> +RELOC_DEPS = $(BASEDIR)/include/asm-x86/config.h $(BASEDIR)/include/xen/compiler.h \
> +	     $(BASEDIR)/include/xen/multiboot.h $(BASEDIR)/include/xen/multiboot2.h
>  
>  head.o: reloc.S
>  
> diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
> index 6180783..7861057 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>
> @@ -32,6 +33,59 @@ ENTRY(start)
>          .long   MULTIBOOT_HEADER_FLAGS
>          /* 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_BASIC_MEMINFO
> +        .long   MULTIBOOT2_TAG_TYPE_MMAP
> +.Lmultiboot2_info_req_end:
> +
> +        .align  MULTIBOOT2_TAG_ALIGN
> +        .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 +135,51 @@ __start:
>          mov     %ecx,%es
>          mov     %ecx,%ss
>  
> +        /* Bootloaders may set multiboot[12].mem_lower to a nonzero value */
> +        xor     %edx,%edx
> +
>          /* Check for Multiboot bootloader */
>          cmp     $MULTIBOOT_BOOTLOADER_MAGIC,%eax
> -        jne     not_multiboot
> +        je      multiboot1_proto
>  
> +        /* Check for Multiboot2 bootloader */
> +        cmp     $MULTIBOOT2_BOOTLOADER_MAGIC,%eax
> +        je      multiboot2_proto
> +
> +        jmp     not_multiboot
> +
> +multiboot1_proto:
> +        /* Get mem_lower from Multiboot information */
> +        testb   $MBI_MEMLIMITS,(%ebx)
> +        jz      trampoline_setup    /* not available? BDA value will be fine */
> +
> +        mov     MB_mem_lower(%ebx),%edx
> +        jmp     trampoline_setup
> +
> +multiboot2_proto:
> +        /* Skip Multiboot2 information fixed part */
> +        lea     MB2_fixed_sizeof(%ebx),%ecx
> +
> +0:
> +        /* Get mem_lower from Multiboot2 information */
> +        cmpl    $MULTIBOOT2_TAG_TYPE_BASIC_MEMINFO,(%ecx)
> +        jne     1f
> +
> +        mov     MB2_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     MB2_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 +194,6 @@ __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     MB_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
> @@ -118,9 +210,9 @@ __start:
>  
>          /* Save the Multiboot info struct (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(multiboot_ptr)
>  
>          /* Initialize BSS (no nasty surprises!) */
> diff --git a/xen/arch/x86/boot/reloc.c b/xen/arch/x86/boot/reloc.c
> index f964cda..4b89838 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, 2015 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"
>      );
>  
> @@ -31,7 +38,16 @@ 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"
> +
> +#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)
>  {
> @@ -49,6 +65,11 @@ static u32 alloc_struct(u32 bytes)
>      return s;
>  }
>  
> +static void zero_struct(u32 s, u32 bytes)
> +{
> +    asm volatile("rep stosb" : "+D" (s), "+c" (bytes) : "a" (0) : "memory");
> +}
> +
>  static u32 copy_struct(u32 src, u32 bytes)
>  {
>      u32 dst, dst_asm;
> @@ -74,40 +95,153 @@ static u32 copy_string(u32 src)
>      return copy_struct(src, p - (char *)src + 1);
>  }
>  
> -multiboot_info_t *reloc(multiboot_info_t *mbi_old)
> +static multiboot_info_t *mbi_mbi(void *mbi_in)
>  {
> -    multiboot_info_t *mbi = (multiboot_info_t *)copy_struct((u32)mbi_old, sizeof(*mbi));
>      int i;
> +    multiboot_info_t *mbi_out;
>  
> -    if ( mbi->flags & MBI_CMDLINE )
> -        mbi->cmdline = copy_string(mbi->cmdline);
> +    mbi_out = (multiboot_info_t *)copy_struct((u32)mbi_in, sizeof(*mbi_out));
>  
> -    if ( mbi->flags & MBI_MODULES )
> +    if ( mbi_out->flags & MBI_CMDLINE )
> +        mbi_out->cmdline = copy_string(mbi_out->cmdline);
> +
> +    if ( mbi_out->flags & MBI_MODULES )
>      {
>          module_t *mods = (module_t *)copy_struct(
> -            mbi->mods_addr, mbi->mods_count * sizeof(module_t));
> +            mbi_out->mods_addr, mbi_out->mods_count * sizeof(module_t));
>  
> -        mbi->mods_addr = (u32)mods;
> +        mbi_out->mods_addr = (u32)mods;
>  
> -        for ( i = 0; i < mbi->mods_count; i++ )
> +        for ( i = 0; i < mbi_out->mods_count; i++ )
>          {
>              if ( mods[i].string )
>                  mods[i].string = copy_string(mods[i].string);
>          }
>      }
>  
> -    if ( mbi->flags & MBI_MEMMAP )
> -        mbi->mmap_addr = copy_struct(mbi->mmap_addr, mbi->mmap_length);
> +    if ( mbi_out->flags & MBI_MEMMAP )
> +        mbi_out->mmap_addr = copy_struct(mbi_out->mmap_addr, mbi_out->mmap_length);
>  
> -    if ( mbi->flags & MBI_LOADERNAME )
> -        mbi->boot_loader_name = copy_string(mbi->boot_loader_name);
> +    if ( mbi_out->flags & MBI_LOADERNAME )
> +        mbi_out->boot_loader_name = copy_string(mbi_out->boot_loader_name);
>  
>      /* Mask features we don't understand or don't relocate. */
> -    mbi->flags &= (MBI_MEMLIMITS |
> -                   MBI_CMDLINE |
> -                   MBI_MODULES |
> -                   MBI_MEMMAP |
> -                   MBI_LOADERNAME);
> +    mbi_out->flags &= (MBI_MEMLIMITS |
> +                       MBI_CMDLINE |
> +                       MBI_MODULES |
> +                       MBI_MEMMAP |
> +                       MBI_LOADERNAME);
>  
> -    return mbi;
> +    return mbi_out;
> +}
> +
> +static multiboot_info_t *mbi2_mbi(void *mbi_in)
> +{
> +    module_t *mbi_out_mods;
> +    memory_map_t *mmap_dst;
> +    multiboot2_memory_map_t *mmap_src;
> +    multiboot2_tag_t *tag;
> +    multiboot_info_t *mbi_out;
> +    u32 ptr;
> +    unsigned int i, mod_idx = 0;
> +
> +    mbi_out = (multiboot_info_t *)alloc_struct(sizeof(*mbi_out));
> +    zero_struct((u32)mbi_out, sizeof(*mbi_out));
> +
> +    /* Skip Multiboot2 information fixed part. */
> +    tag = mbi_in + sizeof(multiboot2_fixed_t);
> +
> +    for ( ; ; )
> +    {
> +        if ( tag->type == MULTIBOOT2_TAG_TYPE_MODULE )
> +            ++mbi_out->mods_count;
> +        else if ( tag->type == MULTIBOOT2_TAG_TYPE_END )
> +        {
> +            mbi_out->flags = MBI_MODULES;
> +            mbi_out->mods_addr = alloc_struct(mbi_out->mods_count * sizeof(module_t));
> +            mbi_out_mods = (module_t *)mbi_out->mods_addr;
> +            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_in + sizeof(multiboot2_fixed_t);
> +
> +    for ( ; ; )
> +    {
> +        switch ( tag->type )
> +        {
> +        case MULTIBOOT2_TAG_TYPE_BOOT_LOADER_NAME:
> +            mbi_out->flags |= MBI_LOADERNAME;
> +            ptr = (u32)get_mb2_data(tag, multiboot2_tag_string_t, string);
> +            mbi_out->boot_loader_name = copy_string(ptr);
> +            break;
> +
> +        case MULTIBOOT2_TAG_TYPE_CMDLINE:
> +            mbi_out->flags |= MBI_CMDLINE;
> +            ptr = (u32)get_mb2_data(tag, multiboot2_tag_string_t, string);
> +            mbi_out->cmdline = copy_string(ptr);
> +            break;
> +
> +        case MULTIBOOT2_TAG_TYPE_BASIC_MEMINFO:
> +            mbi_out->flags |= MBI_MEMLIMITS;
> +            mbi_out->mem_lower = get_mb2_data(tag, multiboot2_tag_basic_meminfo_t, mem_lower);
> +            mbi_out->mem_upper = get_mb2_data(tag, multiboot2_tag_basic_meminfo_t, mem_upper);
> +            break;
> +
> +        case MULTIBOOT2_TAG_TYPE_MMAP:
> +            mbi_out->flags |= MBI_MEMMAP;
> +            mbi_out->mmap_length = get_mb2_data(tag, multiboot2_tag_mmap_t, size);
> +            mbi_out->mmap_length -= sizeof(multiboot2_tag_mmap_t);
> +            mbi_out->mmap_length += sizeof(((multiboot2_tag_mmap_t){0}).entries);
> +            mbi_out->mmap_length /= get_mb2_data(tag, multiboot2_tag_mmap_t, entry_size);
> +            mbi_out->mmap_length *= sizeof(memory_map_t);
> +
> +            mbi_out->mmap_addr = alloc_struct(mbi_out->mmap_length);
> +
> +            mmap_src = get_mb2_data(tag, multiboot2_tag_mmap_t, entries);
> +            mmap_dst = (memory_map_t *)mbi_out->mmap_addr;
> +
> +            for ( i = 0; i < mbi_out->mmap_length / 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:
> +            mbi_out_mods[mod_idx].mod_start = get_mb2_data(tag, multiboot2_tag_module_t, mod_start);
> +            mbi_out_mods[mod_idx].mod_end = get_mb2_data(tag, multiboot2_tag_module_t, mod_end);
> +            ptr = (u32)get_mb2_data(tag, multiboot2_tag_module_t, cmdline);
> +            mbi_out_mods[mod_idx].string = copy_string(ptr);
> +            mbi_out_mods[mod_idx].reserved = 0;
> +            ++mod_idx;
> +            break;
> +
> +        case MULTIBOOT2_TAG_TYPE_END:
> +            return mbi_out;
> +
> +        default:
> +            break;
> +        }
> +
> +        /* Go to next Multiboot2 information tag. */
> +        tag = (multiboot2_tag_t *)(ALIGN_UP((u32)tag + tag->size, MULTIBOOT2_TAG_ALIGN));
> +    }
> +}
> +
> +static multiboot_info_t __used *reloc(void *mbi_in, u32 mb_magic)
> +{
> +    if ( mb_magic == MULTIBOOT2_BOOTLOADER_MAGIC )
> +        return mbi2_mbi(mbi_in);
> +    else
> +        return mbi_mbi(mbi_in);
>  }
> diff --git a/xen/arch/x86/x86_64/asm-offsets.c b/xen/arch/x86/x86_64/asm-offsets.c
> index 447c650..ca3712f 100644
> --- a/xen/arch/x86/x86_64/asm-offsets.c
> +++ b/xen/arch/x86/x86_64/asm-offsets.c
> @@ -13,6 +13,7 @@
>  #include <asm/fixmap.h>
>  #include <asm/hardirq.h>
>  #include <xen/multiboot.h>
> +#include <xen/multiboot2.h>
>  
>  #define DEFINE(_sym, _val)                                                 \
>      asm volatile ("\n.ascii\"==>#define " #_sym " %0 /* " #_val " */<==\"" \
> @@ -166,4 +167,9 @@ void __dummy__(void)
>      OFFSET(MB_flags, multiboot_info_t, flags);
>      OFFSET(MB_cmdline, multiboot_info_t, cmdline);
>      OFFSET(MB_mem_lower, multiboot_info_t, mem_lower);
> +    BLANK();
> +
> +    DEFINE(MB2_fixed_sizeof, sizeof(multiboot2_fixed_t));
> +    OFFSET(MB2_tag_size, multiboot2_tag_t, size);
> +    OFFSET(MB2_mem_lower, multiboot2_tag_basic_meminfo_t, mem_lower);
>  }
> diff --git a/xen/include/xen/multiboot2.h b/xen/include/xen/multiboot2.h
> new file mode 100644
> index 0000000..09ee64e
> --- /dev/null
> +++ b/xen/include/xen/multiboot2.h
> @@ -0,0 +1,169 @@
> +/*
> + *  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
> +#define MULTIBOOT2_HEADER_TAG_ENTRY_ADDRESS_EFI32	8
> +#define MULTIBOOT2_HEADER_TAG_ENTRY_ADDRESS_EFI64	9
> +
> +/* 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
> +#define MULTIBOOT2_TAG_TYPE_EFI32_IH		19
> +#define MULTIBOOT2_TAG_TYPE_EFI64_IH		20
> +
> +/* 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;
> +    u64 pointer;
> +} multiboot2_tag_efi64_t;
> +
> +typedef struct {
> +    u32 type;
> +    u32 size;
> +    u64 pointer;
> +} multiboot2_tag_efi64_ih_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__ */