Bios , Mbr, Grub

[arshad hussain]

> On 04-Jul-2016, at 2:30 pm, Gnoleba GNOGBO <gnognoleba at gmail.com> wrote:
> 
> Hi !
> 
> I had read a lot of book and link about initialization of the boot starting of linux.
> 
> I read that , after the post by the bios the mbr is loaded in memory which routine load this sector ?

This is architecture specific and is done by BIOS.

> In this sector  of 512 bytes we have 440 bytes for a routine what is the function of this routine ?

Actually its 446 bytes. These are executable code.

16bytes per partition * 4 = 64bytes + (0xAA55) 2 bytes for MBR Marker = 66bytes

512 - 66 = 446 bytes

> When this routine is executed ?

Just after POST. Done by BIOS.

> The 2 bytes with 0xAA55 what is its function ?

Its denotes that the sector is executable. Can also be seen as Marker.

> Who load it in memory ? And the all book i had read said the mbr load the loader grub How ? And the grub launch the kernel, ok . How this grub is load ? By which programm ? 
> So, i would like that someone give me the names of routines, the order of their launching and which load or execute what until the grub exécution ?

I would suggest work it floppy on qemu/bochs first to understand then gradually 
move on to partition tables and boot loaders. 

Read “Understanding the linux kernel” - System Startup chapter for thorough understanding.

Thanks.

> 
> Thank you for your help.
> Greg i am waiting a lot from you !
> 
> Best regards
> Gnoleba GNOGBO
> 
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies