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(grub.info)Internals

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Hacking GRUB
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   This chapter documents the user-invisible aspect of GRUB.

   As a general rule of software development, it is impossible to keep
the descriptions of the internals up-to-date, and it is quite hard to
document everything. So refer to the source code, whenever you are not
satisfied with this documentation.  Please assume that this gives just
hints to you.

Memory map

The memory map of various components

Embedded data

Embedded variables in GRUB

Filesystem interface

The generic interface for filesystems

Command interface

The generic interface for built-ins

Bootstrap tricks

The bootstrap mechanism used in GRUB

I/O ports detection

How to probe I/O ports used by INT 13H

Memory detection

How to detect all installed RAM

Low-level disk I/O

INT 13H disk I/O interrupts

MBR

The structure of Master Boot Record

Partition table

The format of partition tables

Submitting patches

Where and how you should send patches