[lfs-support] Grub Questions (or how to waist yet ... even more ... precious electrons)

Bruce Dubbs bruce.dubbs at gmail.com
Sat Sep 1 16:02:03 PDT 2012


Mikie wrote:

> How does Grub stage one (which I am told exists in the tiny MBR) know
> where to get stage 2 code and config files?

It's actually a quite complicated process.  Short answer, the install 
program hard codes the location (sector) in the MBR.

Slightly longer answer.  It depends on the partition type.  The most 
common type is MSDOS but GPT is becoming more common and is required for 
disk drives > 2 TB.

For most MSDOS partitions, the boot track immediately follows the MBR 
and has enough code to read the /boot partition for grub modules.  It is 
commonly 62 sectors or 31K long.

   -- Bruce




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