Re: [PATCH v2 5/5] xen/x86: Add multiboot2 protocol support

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

On 24/09/14 18:19, Daniel Kiper wrote:
> Add multiboot2 protocol support. This way we are laying the foundation
> for EFI + GRUB2 + Xen development.
>
> Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>

Much clearer than before.

Can I suggest retroactively renaming the old multiboot bits to
multiboot1 to make a more marked difference between between
"multiboot1_proto" and "multiboot2_proto" ?

It would also be better to split the changing of multiboot1 and
shuffling of memory calculations away from the introduction of multiboot2.

> ---
> v2 - suggestions/fixes:
>    - use "for" instead of "while" for loops
>      (suggested by Jan Beulich),
>    - properly parenthesize macro arguments
>
>     char *boot_loader_name;
>      (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/head.S     |  117 +++++++++++++-
>  xen/arch/x86/boot/reloc.c    |  103 +++++++++++-
>  xen/include/xen/multiboot2.h |  354 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 567 insertions(+), 7 deletions(-)
>  create mode 100644 xen/include/xen/multiboot2.h
>
> diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
> index 7e48833..4331821 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 +34,68 @@ 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!
> +         */
> +        .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 +144,56 @@ __start:
>          mov     %ecx,%es
>          mov     %ecx,%ss
>  
> +        /* Assume multiboot[12].mem_lower is 0 if not set by bootloader */
> +        xor     %edx,%edx
> +

This change does not match its comment, and seems to have appeared from
nowhere.

>          /* 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     4(%ebx),%edx
> +        shl     $10-4,%edx
> +        jmp     trampoline_setup
>  
> +multiboot2_proto:
> +        /* Get Multiboot2 information address */
> +        mov     %ebx,%ecx
> +
> +        /* Skip Multiboot2 information fixed part */
> +        add     $8,%ecx
> +
> +0:
> +        /* Get mem_lower from Multiboot2 information */
> +        cmpl    $MULTIBOOT2_TAG_TYPE_BASIC_MEMINFO,(%ecx)
> +        jne     1f
> +
> +        mov     8(%ecx),%edx
> +        shl     $10-4,%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     4(%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) */
> @@ -99,12 +208,8 @@ __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     4(%ebx),%edx
> -        cmp     $0x100,%edx         /* is the multiboot value too small? */
> +        cmp     $0x4000,%edx        /* is the multiboot value too small? */

You are going to need some justification for changing this lower bound
of memory.

>          jb      2f                  /* if so, do not use it */
> -        shl     $10-4,%edx
>          cmp     %ecx,%edx           /* compare with BDA value */
>          cmovb   %edx,%ecx           /* and use the smaller */
>  
> diff --git a/xen/arch/x86/boot/reloc.c b/xen/arch/x86/boot/reloc.c
> index 35a991e..572421f 100644
> --- a/xen/arch/x86/boot/reloc.c
> +++ b/xen/arch/x86/boot/reloc.c
> @@ -19,9 +19,13 @@ 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))
> +
>  /*
>   * __HERE__ IS ENTRY POINT!!!
>   *
> @@ -143,6 +147,100 @@ static mbd_t *mb_mbd(mbd_t *mbd, multiboot_info_t *mbi)
>      return mbd;
>  }
>  
> +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(u32) * 2;
> +
> +    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(u32) * 2;
> +
> +    for ( ; ; )
> +    {
> +        switch ( tag->type )
> +        {
> +        case MULTIBOOT2_TAG_TYPE_BOOT_LOADER_NAME:
> +            ptr = (u32)((multiboot2_tag_string_t *)tag)->string;
> +            mbd->boot_loader_name = copy_string(ptr);
> +            break;
> +
> +        case MULTIBOOT2_TAG_TYPE_CMDLINE:
> +            ptr = (u32)((multiboot2_tag_string_t *)tag)->string;
> +            mbd->cmdline = copy_string(ptr);
> +            break;
> +
> +        case MULTIBOOT2_TAG_TYPE_BASIC_MEMINFO:
> +            mbd->mem_lower = ((multiboot2_tag_basic_meminfo_t *)tag)->mem_lower;
> +            mbd->mem_upper = ((multiboot2_tag_basic_meminfo_t *)tag)->mem_upper;
> +            break;
> +
> +        case MULTIBOOT2_TAG_TYPE_MMAP:
> +            mbd->mmap_size = ((multiboot2_tag_mmap_t *)tag)->size;
> +            mbd->mmap_size -= sizeof(multiboot2_tag_mmap_t);
> +            mbd->mmap_size += sizeof(((multiboot2_tag_mmap_t){0}).entries);
> +            mbd->mmap_size /= ((multiboot2_tag_mmap_t *)tag)->entry_size;
> +            mbd->mmap_size *= sizeof(memory_map_t);
> +
> +            mbd->mmap = alloc_struct(mbd->mmap_size);
> +
> +            mmap_src = ((multiboot2_tag_mmap_t *)tag)->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 = (u32)((multiboot2_tag_module_t *)tag)->mod_start;
> +            mbd_mods[mod_idx].end = (u32)((multiboot2_tag_module_t *)tag)->mod_end;
> +            ptr = (u32)((multiboot2_tag_module_t *)tag)->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;
> @@ -150,5 +248,8 @@ static mbd_t __used *__reloc(void *mbi, u32 mb_magic)
>      mbd = (mbd_t *)alloc_struct(sizeof(mbd_t));
>      zero_struct((u32)mbd, sizeof(mbd_t));
>  
> -    return mb_mbd(mbd, mbi);
> +    if ( mb_magic == MULTIBOOT_BOOTLOADER_MAGIC )
> +        return mb_mbd(mbd, mbi);
> +    else
> +        return mb2_mbd(mbd, mbi);
>  }
> diff --git a/xen/include/xen/multiboot2.h b/xen/include/xen/multiboot2.h

This multiboot2.h is huge - can we get away with only including struct
definitions for tags we currently use/support?

~Andrew

> new file mode 100644
> index 0000000..47ca08e
> --- /dev/null
> +++ b/xen/include/xen/multiboot2.h
> @@ -0,0 +1,354 @@
> +/*
> + *  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 {
> +    /* Must be MULTIBOOT2_MAGIC - see above.  */
> +    u32 magic;
> +
> +    /* ISA */
> +    u32 architecture;
> +
> +    /* Total header length.  */
> +    u32 header_length;
> +
> +    /* The above fields plus this one must equal 0 mod 2^32. */
> +    u32 checksum;
> +} multiboot2_header_t;
> +
> +typedef struct {
> +    u16 type;
> +    u16 flags;
> +    u32 size;
> +} multiboot2_header_tag_t;
> +
> +typedef struct {
> +    u16 type;
> +    u16 flags;
> +    u32 size;
> +    u32 requests[0];
> +} multiboot2_header_tag_information_request_t;
> +
> +typedef struct {
> +    u16 type;
> +    u16 flags;
> +    u32 size;
> +    u32 header_addr;
> +    u32 load_addr;
> +    u32 load_end_addr;
> +    u32 bss_end_addr;
> +} multiboot2_header_tag_address_t;
> +
> +typedef struct {
> +    u16 type;
> +    u16 flags;
> +    u32 size;
> +    u32 entry_addr;
> +} multiboot2_header_tag_entry_address_t;
> +
> +typedef struct {
> +    u16 type;
> +    u16 flags;
> +    u32 size;
> +    u32 console_flags;
> +} multiboot2_header_tag_console_flags_t;
> +
> +typedef struct {
> +    u16 type;
> +    u16 flags;
> +    u32 size;
> +    u32 width;
> +    u32 height;
> +    u32 depth;
> +} multiboot2_header_tag_framebuffer_t;
> +
> +typedef struct {
> +    u16 type;
> +    u16 flags;
> +    u32 size;
> +    u32 width;
> +    u32 height;
> +    u32 depth;
> +} multiboot2_header_tag_module_align_t;
> +
> +typedef struct {
> +    u8 red;
> +    u8 green;
> +    u8 blue;
> +} multiboot2_color_t;
> +
> +typedef struct __packed {
> +    u64 addr;
> +    u64 len;
> +    u32 type;
> +    u32 zero;
> +} multiboot2_memory_map_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 mod_start;
> +    u32 mod_end;
> +    char cmdline[0];
> +} multiboot2_tag_module_t;
> +
> +typedef struct {
> +    u32 type;
> +    u32 size;
> +    u32 mem_lower;
> +    u32 mem_upper;
> +} multiboot2_tag_basic_meminfo_t;
> +
> +typedef struct {
> +    u32 type;
> +    u32 size;
> +    u32 biosdev;
> +    u32 slice;
> +    u32 part;
> +} multiboot2_tag_bootdev_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 {
> +    u8 external_specification[512];
> +} multiboot2_vbe_info_block_t;
> +
> +typedef struct {
> +    u8 external_specification[256];
> +} multiboot2_vbe_mode_info_block_t;
> +
> +typedef struct {
> +    u32 type;
> +    u32 size;
> +
> +    u16 vbe_mode;
> +    u16 vbe_interface_seg;
> +    u16 vbe_interface_off;
> +    u16 vbe_interface_len;
> +
> +    multiboot2_vbe_info_block_t vbe_control_info;
> +    multiboot2_vbe_mode_info_block_t vbe_mode_info;
> +} multiboot2_tag_vbe_t;
> +
> +typedef struct {
> +    u32 type;
> +    u32 size;
> +
> +    u64 framebuffer_addr;
> +    u32 framebuffer_pitch;
> +    u32 framebuffer_width;
> +    u32 framebuffer_height;
> +    u8 framebuffer_bpp;
> +    u8 framebuffer_type;
> +    u16 reserved;
> +} multiboot2_tag_framebuffer_common_t;
> +
> +typedef struct {
> +    multiboot2_tag_framebuffer_common_t common;
> +
> +    union {
> +        struct {
> +            u16 framebuffer_palette_num_colors;
> +            multiboot2_color_t framebuffer_palette[0];
> +        };
> +        struct {
> +            u8 framebuffer_red_field_position;
> +            u8 framebuffer_red_mask_size;
> +            u8 framebuffer_green_field_position;
> +            u8 framebuffer_green_mask_size;
> +            u8 framebuffer_blue_field_position;
> +            u8 framebuffer_blue_mask_size;
> +        };
> +    };
> +} multiboot2_tag_framebuffer_t;
> +
> +typedef struct {
> +    u32 type;
> +    u32 size;
> +    u32 num;
> +    u32 entsize;
> +    u32 shndx;
> +    char sections[0];
> +} multiboot2_tag_elf_sections_t;
> +
> +typedef struct {
> +    u32 type;
> +    u32 size;
> +    u16 version;
> +    u16 cseg;
> +    u32 offset;
> +    u16 cseg_16;
> +    u16 dseg;
> +    u16 flags;
> +    u16 cseg_len;
> +    u16 cseg_16_len;
> +    u16 dseg_len;
> +} multiboot2_tag_apm_t;
> +
> +typedef struct {
> +    u32 type;
> +    u32 size;
> +    u32 pointer;
> +} multiboot2_tag_efi32_t;
> +
> +typedef struct {
> +    u32 type;
> +    u32 size;
> +    u64 pointer;
> +} multiboot2_tag_efi64_t;
> +
> +typedef struct {
> +    u32 type;
> +    u32 size;
> +    u8 major;
> +    u8 minor;
> +    u8 reserved[6];
> +    u8 tables[0];
> +} multiboot2_tag_smbios_t;
> +
> +typedef struct {
> +    u32 type;
> +    u32 size;
> +    u8 rsdp[0];
> +} multiboot2_tag_old_acpi_t;
> +
> +typedef struct {
> +    u32 type;
> +    u32 size;
> +    u8 rsdp[0];
> +} multiboot2_tag_new_acpi_t;
> +
> +typedef struct {
> +    u32 type;
> +    u32 size;
> +    u8 dhcpack[0];
> +} multiboot2_tag_network_t;
> +
> +typedef struct {
> +    u32 type;
> +    u32 size;
> +    u32 descr_size;
> +    u32 descr_vers;
> +    u8 efi_mmap[0];
> +} multiboot2_tag_efi_mmap_t;
> +#endif /* __ASSEMBLY__ */
> +
> +#endif /* __MULTIBOOT2_H__ */