GRUB 2 now default for new installations

Christopher Chan christopher.chan at bradbury.edu.hk
Fri Jun 12 03:13:43 UTC 2009


>>> Astute multibooters whose other options include a non-Linux OS do _not_
>>> place Grub in the MBR. Better to make that the universal default, never
>>> addressing via MBR, instead leaving the MBR code generic, and using
>>> that generic code with a primary partition containing a Grub that _no_
>>> installed Linux automatially configures. My Grub primaries don't get
>>> mounted as / boot by any Linux installation. I have upwards of 20
>>> multiboot systems, and all use generic MBR code.
>>>       
>
>   
>> Well, as there is no "generic" MBR, what MBR do you use? The Windows' one?
>> Mac OS X's, *BSD's?
>>     
>
> I don't know what '"generic" MBR' is either. I was referring to generic MBR
> _code_, an optional feature of an openSUSE installation, and I'm sure other
> Linux installers. It refers to MBR code that works identically or similarly
> to the MBR code included with IBM DOS, MS DOS, OS/2 and Windows versions from
> two decades ago, which when installed finds an active primary partition on
> the first BIOS HD, if one exists, and transfers control to its PBR if it
> does, and prints an error message if a grand total of exactly one active
> primary does not exist.
>
>   

There is no such thing as 'generic' MBR code. The MBR aka master boot 
record is the first sector of a disk where partition data is written. 
That partition data does not use up all 512 bytes and in fact you have 
about 440 bytes for your OWN code.

That so-called 'MBR code included with IBM PCDOS, MSDOS, OS/2 and 
Windows' is not in fact any code at all but a MBR that only holds 
partition data and has no code installed. The actual finding an active 
primary partition and then loading the boot sector of that partition is 
done by the BIOS.

You can stuff grub2 into the boot sector or into the MBR. Since the BIOS 
first looks at the MBR for something to load before checking the 
partition table, whatever is installed in the MBR gets first priority. 
Just take note of that.

Not that wikipedia is an authority but you can look here too: 
http://en.wikipedia.org/wiki/Master_boot_record




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