Re: Soft RAID and EFI systems

[David Brown <david.brown@hesbynett.no>]

On 04/02/14 09:41, Francis Moreau wrote:
> On 02/02/2014 11:57 PM, Phil Turmel wrote:
>> On 02/02/2014 05:30 PM, Chris Murphy wrote:
>>>
>>> On Feb 2, 2014, at 2:34 PM, Francis Moreau <francis.moro@gmail.com>
>>> wrote:
>>>>
>>>> That's funny because one of the reasons I want to use UEFI firmware
>>>> is to get rid of grub (I don't like it and the way it has become
>>>> such a bloated beast): since /boot is vfat and has its own
>>>> partition, I prefer use a much simpler bootloader such as
>>>> gummyboot.
>>
>> Ditching the bootloader is possible:
>>
>> http://kroah.com/log/blog/2013/09/02/booting-a-self-signed-linux-kernel/
>>
> 
> Well yeah it's possible but not currently usable IMHO. It means that you
> need to build your own kernel, include in this kernel the initramfs
> image and you need to redo the whole process if you want to change a
> single option in the kernel command line.
> 
>> It seems to me that you should be able to create a raid1 v1.0 MD array
>> of your EFI support partitions, and put the combined and signed
>> kernel/initramfs onto it (mirrored to all member drives).
> 
> Are both v0.9 and v1.0 MD  put their metadata at the end of a partition
> ? I thought only v0.9 would do that.

Yes, it is only 0.9 format that is at the end of the partition.  This
means that a plain raid1 mirror (with as many disks as you like, as long
as they are simple mirrors and not raid10) looks just like a normal
partition for other tools.  As long as it is read-only, tools that are
not raid-aware can use it.  For example, grub and lilo can happily boot
from a 0.9 metadata raid1 array just like from a normal partition.
(Actually, modern grub understands a lot of md raid formats.)  The same
thing should apply to EFI, as long as it does not attempt to write to
the partition.

> 
>>
>> Then set the UEFI bios to try each device's ESP in turn.
>>
>> Untested ... :-)
> 
> I'll do :)
> 
> Thanks
>