[arch-general] Quick question about post-MBR gap?

[mike cloaked]

On Wed, Jul 18, 2012 at 7:40 PM, mike cloaked <mike.cloaked at gmail.com> wrote:
> I am planning a test install using the new arch-install-scripts via
> the latest netinstall images from releng (from today's date).
>
> I know that for a system where I blow away all previous disc
> partitions and partition from scratch I can create a 2MiB partition
> (using MBR and NOT GPT partitioning) before the first formatted
> partition on the HD and install grub2 during the base install.
> However can someone please tell me explicitly if, for a system with
> only BIOS (no UEFI at all), and no GPT partitioning but just plain old
> MBR partitioning - is the recommended 2MiB post-MBR gap still a
> "requirement" for that specific situation for grub2 to work? I can't
> find that as an explicit statement in any of the documentation that I
> have read for installs/grub2/partitioning! i.e. does grub2 still need
> to embed the core.img file in the post-MBR gap as the preferred and
> dev recommended approach in this case?
>
> The reason I would like to have that explicit answer is that if I want
> to install arch on a machine which has a pre-existing NTFS partition,
> and possibly host-protected partition as well for Windows recovery, at
> the start of the drive, then if the 2MiB post-MBR gap is a requirement
> (rather than a nicety) for grub2 with BIOS and MBR partitioning (but
> no GPT partitioning or UEFI) then unless the drive is re-partitioned
> and the NTFS partition reduced in size and moved out by 2MiB then
> there could be problems? However doing that partition jinking about
> might itself lead to a few issues!
>
> I am going to do an install with new partitioning on an old laptop to
> check that I can successfully use the new install system (without AIF)
> and hopefully that will work, but I also have other machines with
> existing and important (to me) Windows partitions that I would really
> like to NOT corrupt when installing arch to the partitions on their
> drives.
>
> The other reason I am asking this question is that I also have
> existing dual boot laptops with Windows XP and arch with BIOS and MBR
> partitioning - and at some point it would presumably be sensible to
> move from the existing grub to grub2 - and on these systems where I
> have already checked that there is only a 64 sector post-MBR gap -
> will this lead to problems if I change from grub to grub2 if I don't
> change the partitions to have a 2MiB post-MBR gap?
>
> Thanks for any help on this - I have been doing reading and trying to
> prepare without looking an idiot and being a good arch admin, but
> there is quite a lot to read and I still can't find the answer to the
> explicit question above!
>
> --
> mike c

I just realised that the current build of the netinstall isos still
have grub legacy and not grub2 - so I will wait for my first test
install - but my questions above remain keenly awaiting some replies
anyway!

Thanks

-- 
mike c