Grub Manual

[Les Mikesell]

William Case wrote:

>> They can't mesh other than by convention.  When updating the config, 
>> kernel, initrd, etc., files you are working with the OS (doesn't have to 
>> be linux) view of the filesystem and it's relative locations.  When grub 
>> boots, it only has the bios view of things and only sees one partition 
>> through the bios conventions.
>>
> 
> Grub's job is to find partitions and file systems; not to use them.

Grub doesn't 'find' partitions, you tell it where the one it will use is 
  from the bios perspective with the root (hdx,x) directive before 
installing.

> Grub is so powerful exactly because it can find so many different kinds
> of partitions/filesystems and load them and their kernels with their
> various forms of init into memory.

That's true, and it makes it possible to change the configuration, 
although not the partition to be used, without reinstalling grub itself 
as you would with lilo.  However, it still doesn't know/care what the OS 
it is booting will call those partitions or if they are subsequently 
mounted at all.

> To do that Grub needs its own generic file system (rudimentary though it
> is) and it's own small kernel that allows it to operate on *any*
> machine.  The manuals (although I agree they could have some basic (less
> technical) explanations included) deal only with the GRUB file system
> and kernel making no assumptions about the partitions/files/kernel(s)
> that will eventually be loaded.

And the missing piece is that you - or the distro-packaged scripts - 
update those locations through the OS concepts of where that partition 
is mounted.  This part is OS/distro specific and doesn't have a lot to 
do with grub.

-- 
   Les Mikesell
    lesmikesell at gmail.com