[arch-general] grub/grub2 final - some questions

[Keshav P R]

On Wed, Jun 27, 2012 at 2:27 PM, mike cloaked <mike.cloaked at gmail.com> wrote:
> Subject: Re: [arch-dev-public] grub/grub2 final
> On Sun, Jun 24, 2012 at 8:51 PM, Ronald van Haren <pressh at gmail.com> wrote:
>
>> I was about to post a similar message...
>>
>> Anyway, I was planning to drop support of grub1. There has been no
>> upstream for a long time and all newer features are patched in or
>> require additional patches. I don't see a need to have it in [extra]
>> as grub-legacy. No problem uploading it to AUR so people can continue
>> to use it if they want, although you need i686 to build it so that
>> could be the only reason to keep it in [extra] for a bit...
>>
>> I've seen no major breakages in grub2 since beta2 iirc. Upstream
>> development has been going towards stability in recent betas and I
>> would consider it stable at the moment: there were no real bug reports
>> in the bugtracker for the last few months.
>>
>> I'd like to move 2.00 to [core] via [testing] when it is released,
>> letting the grub-bios (atm grub2-bios) replace the old grub package.
>> Adding an install message and a news item is probably a good idea at
>> the time.
>>
>> I'll be pushing grub2 rc1 to [testing] in a moment if you want to give
>> it a try. Final 2.00 release should be in one of the next days.
>
> I am slightly confused by some of the options that will become
> available once grub2 becomes the supported package in [core].
>
> For someone who currently has hardware without EFI firmware (or any
> choice of switching in the BIOS menus), and boots via BIOS-grub- and
> with MBR and conventional partitions with an x86_64 arch system - then
> will it still be possible to boot with the only change being to move
> from grub to grub2 (using grub2-bios)?   I am certainly confused about
> how UEFI fits in with that scenario.  Would it be the same for someone
> running as above with 32 bit packages only?
>

I assume you are talking about non-UEFI systems which are currently
booting via grub-legacy, ie current core/grub or aur/grub-gfx . For
such systems, once grub-bios (aka grub2-bios) is installed, the user
has to follow https://wiki.archlinux.org/index.php/GRUB#Install_to_440-byte_MBR_boot_code_region
to install grub(2)'s boot code in the MBR. Then follow
https://wiki.archlinux.org/index.php/GRUB#Generate_GRUB2_BIOS_Config_file
to generate grub.cfg . This is in case of BIOS+MBR booting.

> For a system based on hardware without EFI so that there is no option
> in the "BIOS" to switch from BIOS to EFI is there some magic that
> needs to happen for the BIOS to boot and then load UEFI code and
> support GPT partitions?
>

Unless the firmware supports UEFI boot, there is no way to use UEFI
boot method. But grub(2) fully supports BIOS-GPT configuration. The
need for UEFI in case of GPT is true only in case of Windows. In
linux, both grub(2) and syslinux support BIOS-GPT, but in different
ways. See https://wiki.archlinux.org/index.php/GUID_Partition_Table#BIOS_systems
for more info. You can convert an existing MBR setup to GPT using
gdisk https://wiki.archlinux.org/index.php/GUID_Partition_Table#Convert_from_MBR_to_GPT
.
> Maybe I am the only one who is confused about these linked changes to
> BIOS/UEFI grub/grub2 and the system partitioning MBR/GPT?  Is there a
> good clear link to an explanation of how this all fits together and
> what the options will be?
>
> I guess that in the future hardware will increasingly be purchased
> which has UEFI enabled by default (and at some point BIOS will
> presumably vanish altogether) with huge hard drive capacities, but at
> the moment many systems purchased in the past decade and still in use
> are not UEFI based, so the choices available to users need to be clear
> as grub2 and new options and code are developed for the boot process.
>
> Thanks in advance.
>

Archwiki has very good info on GRUB(2), GPT and UEFI. The GRUB(2)
article particularly might seem big and this gives an idea to users
that grub(2) is very complex to setup. The article is big because it
explains all the possible scenarios/configs in which grub(2) can be
installed. But setting up any one scenario is a simple task involving
just four steps

1. Partition according to requirements - ie. Post-MBR gap in MBR or
bios_grub partition in GPT systems for grub(2) bios booting
2. Install grub-* package (currently grub2-*) as per requirement and
run grub-install as per archwiki grub(2) article. This populates
/boot/grub and install gurb(2) boot code to the MBR. In short it sets
up everything except you config file
3. Run grub-mkconfig or grub-menulst2cfg to generate grub.cfg (menu/config file)
4. Copy additional grub(2) font and/or locale files as detailed in the wiki.

Do not get confused with bios boot and uefi boot. UEFI is a totally
different beast and has to be tackled differently. Everything I have
mentioned in this post is only for an user changing from grub-legacy
BIOS-MBR booting to grub(2) BIOS-MBR or BIOS-GPT booting.

Regards.

Keshav