grub (v1) in f18?

[Chris Murphy]

On Dec 7, 2012, at 10:24 AM, "Richard W.M. Jones" <rjones at redhat.com> wrote:

> On Thu, Dec 06, 2012 at 03:25:21PM -0700, Chris Murphy wrote:
>> Why is a boot manager needed for a virtualized guest? It seems like all you need is to point to a virtual disk (or current or past snapshot) and go directly to loading the kernel. 
>> 
>> If I could stuff < 1024 bytes of boot loader into ext4's two boot sectors, that seems ways easier than dealing with grub.
>> http://lists.fedoraproject.org/pipermail/devel/2012-December/174786.html
> 
> [My second answer, now that I've looked at that code and understand
> better where you're going with this …]

I'm casually suggesting a vastly simpler means of boot loading a VM that doesn't have a dependency on grub. The host VM interface acting as the boot manager.
> 
> Yes, I think this is all possible, and probably better than emulating
> what the BIOS does.  Even better would be if you could get those 1024
> bytes down to 512 bytes (and thus fit it in a boot sector).  Then no
> changes to existing hypervisors would be needed at all, and it would
> run on baremetal.

ext[234] has two boot sectors for a total of 1024 bytes. XFS has none. Btrfs has 64KB.

It just seems like GRUB is a really familiar 4000 meter cargo train, compared to an unfamiliar hand truck, for the task of moving half-dozen boxes. Maybe I'm underestimating the size/weight of those boxes, but maintaining a grub installation, let alone troubleshooting it if it breaks for some reason, is a lot more complicated than some external source rewriting 1024 bytes to merely two sectors.


Chris Murphy