Help: Loading Stage Two Bootloader From Stage One Bootloader

Index > OS Construction > Help: Loading Stage Two Bootloader From Stage One Bootloader

Author

Thread

uautkarsh

Joined: 30 Mar 2012
Posts: 8
Location: India

uautkarsh 01 Apr 2012, 11:06

My Stage One bootloader is 16 bit, its assembled Raw Binary File..
The Second Stage bootloader is also a 16 bit, its again assembled Raw Binary File..

The Second Stage Bootloader is copy and pasted on the floppy disk, rather that copying it to some particular sector.. Now my question is how can i find the second stage bootloader using the Stage one bootloader..??

The file system is FAT12..

01 Apr 2012, 11:06

SeproMan

Joined: 11 Oct 2009
Posts: 70
Location: Belgium

SeproMan 01 Apr 2012, 12:56

Take a look at the bootloader at the end of this post. It's just what you need!
http://board.flatassembler.net/topic.php?t=11748

_________________
Real Address Mode.

01 Apr 2012, 12:56

uautkarsh

Joined: 30 Mar 2012
Posts: 8
Location: India

uautkarsh 01 Apr 2012, 17:18

Ok.. I will try to understand the code.. Thanks a lot.. Smile

Tell me one more thing..
Suppose my kernel is in C.. Then how should i compile it so that the Bootloader(you have given the link for) may load it..

01 Apr 2012, 17:18

xleelz

Joined: 12 Mar 2011
Posts: 86
Location: In Google Code Server... waiting for someone to download me

xleelz 01 Apr 2012, 18:27

Note: Some thinking required...
http://wiki.osdev.org/Bare_Bones

01 Apr 2012, 18:27

uautkarsh

Joined: 30 Mar 2012
Posts: 8
Location: India

uautkarsh 02 Apr 2012, 17:49

@xleelz: Thanks a lot.. I dinn see that.. Razz

02 Apr 2012, 17:49

ACP

Joined: 23 Sep 2006
Posts: 204

ACP 03 Apr 2012, 08:41

uautkarsh wrote:

Suppose my kernel is in C.. Then how should i compile it so that the Bootloader(you have given the link for) may load it..

That really depends on what you want to achieve and how much work you would like to invest into it. You can compile it as MZ,PE or ELF file for example assuming you will include appropriate process loader into second stage bootloader. The other option is to make it raw binary and load it into predefined address space and just jump to correct entry point.

The decision should also be based on your architectural decision like: when do you enable memory management, do you use protected mode or long mode etc and on which system booting stage you enable those CPU/system features.

03 Apr 2012, 08:41

uautkarsh

Joined: 30 Mar 2012
Posts: 8
Location: India

uautkarsh 03 Apr 2012, 14:59

Ok.. I haven't thought of this much..
Anyways.. In my second Bootloader i will go into the protected mode..
I will try all the above suggestions.. Smile

Thanks a lot..

03 Apr 2012, 14:59

flash

Joined: 11 Mar 2006
Posts: 55
Location: Cuba

flash 05 Apr 2012, 14:56

Or you can use GRUB, jejeje. This is a basic template for a multiboot compilant binary code:

Code:

bits 32
MULTIBOOT_HEADER_MAGIC    equ 0x1BADB002
MULTIBOOT_HEADER_FLAGS        equ 0x00010000
CHECKSUM              equ -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS)
LOADBASE              equ 0x00100000          ; the load base address
org LOADBASE

                 jmp     multiboot_entry

align    4
multiboot_header:
                  dd MULTIBOOT_HEADER_MAGIC
                   dd MULTIBOOT_HEADER_FLAGS
                   dd CHECKSUM
                 dd multiboot_header
                 dd LOADBASE
                 dd 0
                        dd 0
                        dd multiboot_entry
     
multiboot_entry:
                 ; as much code as the file system support

05 Apr 2012, 14:56

< Last Thread | Next Thread >

Forum Rules:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum