Only kernels loaded at 1 megabyte or above are presently supported.Any attempt to load below that boundary will simply result in immediate failure and an error message reporting the problem.By around 2007, GNU/Linux distributions started to use GRUB 2 to limited extents, and by the end of 2009 multiple major distributions were installing it by default.GRUB 2 is a rewrite of GRUB (see History), although it shares many characteristics with the previous version, now known as GRUB Legacy.Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections. The kernel, in turn, initializes the rest of the operating system (e.g. GNU GRUB is a very powerful boot loader, which can load a wide variety of free operating systems, as well as proprietary operating systems with chain-loading.GRUB is designed to address the complexity of booting a personal computer; both the program and this manual are tightly bound to that computer platform, although porting to other platforms may be addressed in the future.This function is both automatic and transparent to the user (i.e.all functions operate upon the uncompressed contents of the specified files).
Unlike many other boot loaders, GRUB makes the particular drive translation irrelevant.See Obtaining and Building GRUB, for more information.Over the next few years, GRUB was extended to meet many needs, but it quickly became clear that its design was not keeping up with the extensions being made to it, and we reached the point where it was very difficult to make any further changes without breaking existing features. Okuji started work on PUPA (Preliminary Universal Programming Architecture for GNU GRUB), aiming to rewrite the core of GRUB to make it cleaner, safer, more robust, and more powerful.In addition to the requirements above, GRUB has the following features (note that the Multiboot Specification doesn’t require all the features that GRUB supports): Support a human-readable text configuration file with preset boot commands.You can also load another configuration file dynamically and embed a preset configuration file in a GRUB image file.He soon realized that it would be a lot easier to write his own boot loader from scratch than to keep working on the Free BSD boot loader, and so GRUB was born.