From which point onwards the kernel execution starts

From which point onwards the kernel execution starts

[AQ Tast]

Hello Everyone,


I am studying bootloaders and wanted to know which function exactly the 
kernel starts from , i.e. where is the main function?

I been through the init/main.c file and I think most likely this is the 
file. Could someone please explain how the kernel initializes, i.e. I 
want to know how does kernel starts from main function

From which point onwards the kernel execution starts

[Mulyadi Santosa]

On Sat, Mar 5, 2011 at 12:42, AQ Tast <tasteaq@gmail.com> wrote:
>  Could someone please explain how the kernel initializes, i.e. I
> want to know how does kernel starts from main function

http://www.ibm.com/developerworks/linux/library/l-linuxboot/

-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

From which point onwards the kernel execution starts

[Andrzej Kardas]

On Sat, Mar 5, 2011 at 12:42, AQ Tast <tasteaq@gmail.com> wrote:
>>   Could someone please explain how the kernel initializes, i.e. I
>> want to know how does kernel starts from main function
> http://www.ibm.com/developerworks/linux/library/l-linuxboot/
>
It's quite good article at start, but it is a bit old and doesn't cover 
the newest kernel. If you want to get the details i suggest read great 
post on Gustawo Duarte blog:

http://duartes.org/gustavo/blog/post/kernel-boot-process

Very useful is Makefile

http://lxr.linux.no/#linux+v2.6.37.2/Makefile

you can trace kernel building process step by step and see what files 
are linking into kernel in which order.

On the other hand, you have always up to date documentation of Kernel 
Boot Process in documentation directory in kernel sources:

http://lxr.linux.no/#linux+v2.6.37.2/Documentation/x86/boot.txt

If you want to trace linux boot process in source code, you probably 
want to start at line:


_start:
                 # Explicitly enter this as bytes, or the assembler
                 # tries to generate a 3-byte jump here, which causes
                 # everything else to push off to the wrong offset.
                 .byte   0xeb            # short (2-byte) jump
                 .byte   start_of_setup-1f

in arch/x86/boot/header.S  
(http://lxr.linux.no/#linux+v2.6.37.2/arch/x86/boot/header.S#L108_) for 
x86 architecture.

Have fun in exploring :)

-- 
regards,
Andrzej Kardas

From which point onwards the kernel execution starts

[Mulyadi Santosa]

Hi :)

On Sat, Mar 5, 2011 at 17:41, Andrzej Kardas <andrzej-kardas@o2.pl> wrote:
> It's quite good article at start, but it is a bit old and doesn't cover
> the newest kernel. If you want to get the details i suggest read great
> post on Gustawo Duarte blog:
>
> http://duartes.org/gustavo/blog/post/kernel-boot-process

Wow!!!! great blog post there... a must read for me and possibly the
rest of all newbies here....

Oh and I forgot my usual tips in such case: use qemu...attach gdb to
qemu's gdb stub.... use -s and -S options...it will stop the guest
invocation right from the initial startup. Assuming you compile guest
kernel with frame pointer and sufficient debug symbols, it would be
easy for you to explore the kernel code :)

-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

From which point onwards the kernel execution starts

[Andrzej Kardas]

On 06.03.2011 09:01, Mulyadi Santosa wrote:
>
> Oh and I forgot my usual tips in such case: use qemu...attach gdb to
> qemu's gdb stub.... use -s and -S options...it will stop the guest
> invocation right from the initial startup. Assuming you compile guest
> kernel with frame pointer and sufficient debug symbols, it would be
> easy for you to explore the kernel code :)
>
Let me add some stuff to Your tips :). If we talking about qemu and gdb, 
if somebody doesn't like console-oriented tools (who doesn't ?? :) ), 
anyway  there is possibility to use qemu and gdb with very popular IDE - 
Eclipse and trace execution of kernel code with "magnificent graphical 
interface".

The recipe how configure Eclipse + qemu + gdb :

http://issaris.blogspot.com/2007/12/download-linux-kernel-sourcecode-from.html


--
regards
Andrzej Kardas
http://www.linux.mynotes.pl

From which point onwards the kernel execution starts

[Mulyadi Santosa]

On Sun, Mar 6, 2011 at 17:26, Andrzej Kardas <andrzej-kardas@o2.pl> wrote:
> The recipe how configure Eclipse + qemu + gdb :
>
> http://issaris.blogspot.com/2007/12/download-linux-kernel-sourcecode-from.html

oh my gooodnesss ! that's great...thanks for sharing.... :)

-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

From which point onwards the kernel execution starts

[Ashwath]

Thanks a lot :) had been looking for a long time...



On Mon, Mar 7, 2011 at 9:48 PM, Mulyadi Santosa
<mulyadi.santosa@gmail.com>wrote:

> On Sun, Mar 6, 2011 at 17:26, Andrzej Kardas <andrzej-kardas@o2.pl> wrote:
> > The recipe how configure Eclipse + qemu + gdb :
> >
> >
> http://issaris.blogspot.com/2007/12/download-linux-kernel-sourcecode-from.html
>
> oh my gooodnesss ! that's great...thanks for sharing.... :)
>
> --
> regards,
>
> Mulyadi Santosa
> Freelance Linux trainer and consultant
>
> blog: the-hydra.blogspot.com
> training: mulyaditraining.blogspot.com
>
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
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