[CentOS] Installing CentOS7 boot loader into the /boot partition

[Lamar Owen]

On 07/17/2014 02:41 PM, Edward Diener wrote:
> Programming is about calculations as well as logic. It cannot be 
> impossible to calculate how big core.img is, how much space is in the 
> partition in which grub2 is installed and either tell the end-user it 
> can or cannot be done. Things like "it's bad to install grub2 into a 
> partition" mean nothing in the computer programming world. The first 
> rule of programming: the bit is on or it is off. 

What the error message is saying is that 'we know the bootloader is too 
big to fit in the partition's boot sector, so we hide it with 
blocklists, but they're unreliable (filesystem utilities could 
potentially overwrite them), and so that makes it a bad idea.' The 
--force parameter is the user telling grub-setup 'I know you know it's 
too big and will use blocklists and they're unreliable but I don't care: 
use them anyway!' The bootloader has a significant amount of code that 
is not inside the filesystem and either must 'hide' in the partition's 
boot sector or be hidden by 'lying' about the sectors that the 
bootloader is using (the blocklist method).

The programmers at the GNU GRUB project have determined that it is not 
reliably supportable to put GRUB2 on a partition, rather than putting it 
in the MBR (a whole different ball of wax is EFI boot support.....).  
Correcting this is something that the GRUB project people will have to 
properly fix (and it's probably not easy to do, or they would have 
already done it).  The Fedora project supports it, at least as far as 
Fedora *supports* anything (that is, if it breaks, you keep the pieces) 
whereas an Enterprise distribution with paying customers can't 
reasonably do that, since if it breaks they have to support fixing it.  
That's what the service contract buys, after all.

The CentOS project rebuilds that Enterprise linux distribution verbatim, 
as so won't support it either, until the upstream supports it.

But if you want to do it manually, you can.  And I will be trying this, 
but on a bit of an oddball system, not your run-of-the-mill 
BIOS-boot-to-MBR systems.