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Re: 512 byte boot.img


From: Felix Miata
Subject: Re: 512 byte boot.img
Date: Fri, 14 Jan 2011 23:11:45 -0500
User-agent: Mozilla/5.0 (OS/2; Warp 4.5; rv:2.0b8pre) Gecko/20101030 SeaMonkey/2.1b2pre

On 2011/01/14 22:11 (GMT-0500) address@hidden composed:

From the grub2 manual

boot.img
     On PC BIOS systems, this image is the first part of GRUB to start. It is 
written to a master boot record (MBR) or to the boot sector of a partition. 
Because a PC boot sector is 512 bytes, the size of this image is exactly 512 
bytes.

I always thought that the 512 byte MBR also includes the Partition-Table. So 
with the boot.img being 512 bytes and being written to the disk root sector 
what happens to the PT?

Grub boot sector code does not occupy 512 bytes. Installation involves merging the existing partition table into the image before it gets written to the target sector so that the table will appear to have been left untouched. It's magic. :-)
--
"How much better to get wisdom than gold, to choose
understanding rather than silver." Proverbs 16:16 NKJV

 Team OS/2 ** Reg. Linux User #211409

Felix Miata  ***  http://fm.no-ip.com/



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