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 Post subject: Multiboot 2
PostPosted: Mon Oct 26, 2015 5:19 pm 
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Joined: Mon Oct 19, 2015 12:36 pm
Posts: 13
I'm trying to use Multiboot 2 (http://nongnu.askapache.com/grub/phcoder/multiboot.pdf) but I'm getting a "no multiboot header" found error.

boot.S

Code:
.extern kernel_main

.section .multiboot2

multiboot2_header_start:
/* magic number */
.long   0xe85250d6
/* architecture */
.long   0
/* header size */
.long   multiboot2_header_end - multiboot2_header_start
/* checksum */
.long   -(0xe85250d6 + (multiboot2_header_end - multiboot2_header_start))

/* tag end */
.align 8
.short   0
.short   0
.long   8
multiboot2_header_end:

# Reserve a stack for the initial thread.
.section .bootstrap_stack, "aw", @nobits
stack_bottom:
.skip 16384 # 16 KiB
stack_top:

.section .text.init

.global _start
.type _start, @function
_start:
   movl $stack_top, %esp

   /* Reset EFLAGS. */
   pushl   $0
   popf

   pushl %ebx
   pushl %eax

   call kernel_main

   cli
   hlt
.Lhang:
   jmp .Lhang

# Set the size of the _start symbol to the current location '.' minus its start.
# This is useful when debugging or when you implement call tracing.
.size _start, . - _start   


linker.ld

Code:
BOOT_ADDRESS   = 0x00100000;

PAGE_SIZE      = 0x1000;

ENTRY(_start)
SECTIONS {
   . = BOOT_ADDRESS;
   .text.init : {
      . = ALIGN(8);
      *(.multiboot2)
      *(.text.init)
   } : boot

   .data.init : {
      *(.data.init)
   }

   .bss.init : {
      *(.bss.init)
   }

   .text ALIGN(PAGE_SIZE) : AT(ADDR(.text)) {
      *(.text)
   } : text

   .rodata ALIGN(PAGE_SIZE) : AT(ADDR(.rodata)) {
      *(.rodata)
   } : rodata

   .data ALIGN(PAGE_SIZE) : AT(ADDR(.data)) {
      *(.data)
   } : data

   .bss ALIGN(PAGE_SIZE) : AT(ADDR(.bss)) {
      *(.bss)
      *(.bootstrap_stack)
   }

   kernel_image_size = .;
}

PHDRS {
   headers   PT_PHDR FILEHDR PHDRS;
   boot   PT_LOAD;
   text   PT_LOAD;
   rodata   PT_LOAD;
   data   PT_LOAD;
}


multiboot.h

http://fossies.org/linux/grub/include/multiboot2.h

main.cpp

Code:
#include <stddef.h>
#include <stdint.h>

void WriteCharacter(unsigned char c, unsigned char forecolour, unsigned char backcolour, int x, int y)
{
     uint16_t attrib = (backcolour << 4) | (forecolour & 0x0F);
     volatile uint16_t * where;
     where = (volatile uint16_t *)0xB8000 + (y * 80 + x) ;
     *where = c | (attrib << 8);
}

extern "C"
void kernel_main(uint32_t magic, uint32_t addr)
{
   WriteCharacter('A', 15, 0, 0, 0);
}


grub.cfg

Code:
menuentry "myos" {
   multiboot /boot/myos.bin
}


mkiso.sh

Code:
#!/bin/bash
mkdir -p isodir/boot/grub
cp myos.bin isodir/boot/myos.bin
cp grub.cfg isodir/boot/grub/grub.cfg
grub2-mkrescue -o myos.iso isodir


Compile commands

Code:
i686-elf-as boot.S -o boot.o
i686-elf-g++ -std=c++14 -Wall -Wextra -pedantic -O2 -ffreestanding -fno-exceptions -fno-rtti -c main.cpp -o main.o
i686-elf-g++ -T linker.ld -o myos.bin -ffreestanding -O2 -nostdlib boot.o main.o -lgcc


And I think I have the right grub version:

Code:
grub2-mkrescue --version
grub2-mkrescue (GRUB) 2.02~beta2


Most examples I've seen using Multiboot 2 are targetted for 64-bit and use their own bootloader. I'm starting to think either I have the wrong version of Grub or Grub doesn't implement Multiboot 2.


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 Post subject: Re: Multiboot 2
PostPosted: Mon Oct 26, 2015 7:32 pm 
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Member
Member

Joined: Mon Feb 02, 2015 7:11 pm
Posts: 305
Ya, I lost an hour on that one myself.

Change:

Code:
menuentry "myos" {
   multiboot /boot/myos.bin
}


To:

Code:
menuentry "myos" {
   multiboot2 /boot/myos.bin
}


Grub... Seriously...

_________________
https://github.com/kiznit/rainbow-os


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 Post subject: Re: Multiboot 2
PostPosted: Mon Oct 26, 2015 7:39 pm 
Offline

Joined: Mon Oct 19, 2015 12:36 pm
Posts: 13
kiznit wrote:
Ya, I lost an hour on that one myself..


HAHAHA. Thank you so much.


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 Post subject: Re: Multiboot 2
PostPosted: Fri Nov 01, 2019 9:44 pm 
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Joined: Fri Nov 01, 2019 9:37 pm
Posts: 1
Thanks a lot!
I almost gave up on multiboot2


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