I am building up a laptop to dual boot OpenSuse 12.2 and Windows 7. My PC uses UEFI booting and GUID partition tables. Is it absolutely necessary for me to have a separate partition for /boot/efi? And should this partition be in the FAT format?
Hi
GUID partition table, OK that’s a GPT.
My experience is:
already version 12.1 of openSUSE would install fine from DVD in UEFI booting,
and using a GPT.
Only Windows 7 refused to install on the same hard disk if that had a GPT 
Even if I blanked the hard disk with only the GPT left,
and let the Windows 7 installer run first, it refused to install.
Try it.
It’s Windows 7 that makes the problems, not openSUSE.
If you want to read more on how I found out, see here:
https://forums.opensuse.org/english/get-technical-help-here/install-boot-login/475347-error-occurred-while-installing-grub-during-os-11-4-installation-error-25-asus-efi-bios.html?highlight=EFI
Good luck
Mike
Thanks for the input but let’s please stick to this thread’s question/topic. Thanks!
Please clarify your question. Do you ask whether /boot/efi can be contained in /boot partition? Or do you ask whether you can reuse existing ESP (you should have one because you already has Windows)?
Just to be crystal clear: (1) is it necessary (or maybe recommended) to have a separate partition for /boot/efi (instead of just letting it remain as part of the partition /), (2) should this partition have a FAT file system (and not ext4 for example). I further note that the OpenSUSE installer gives the option “/boot/efi” in the drop down menu instead of just “/boot” in Custom Partitioning for UEFI installation. Thanks!
Using Windows (Fat32) EFI partition is fine. Just mount it in /boot/efi and of course don’t reformat it! Be aware that openSUSE might create a hybrid MBR and that Windows might not boot anymore after that. The problem and the solution are described in this thread: Trouble dual booting 12.2 and Windows 7 on EFI enabled system
Read it first! It’s long but interesting. 
On Wed 09 Jan 2013 09:16:02 AM CST, untarnished wrote:
I am building up a laptop to dual boot OpenSuse 12.2 and Windows 7. My
PC uses UEFI booting and GUID partition tables. Is it absolutely
necessary for me to have a separate partition for /boot/efi? And should
this partition be in the FAT format?
Hi
No, this machine only uses one for Windows 7 and openSUSE. And yes the
partition type needs to be EF00 (FAT)
When installing select the custom partitioning, but don’t let the
openSUSE install format it, you will get a warning but can ignore.
–
Cheers Malcolm °¿° (Linux Counter #276890)
openSUSE 12.2 (x86_64) Kernel 3.4.11-2.16-desktop
up 6:00, 3 users, load average: 0.03, 0.05, 0.05
CPU Intel® i5 CPU M520@2.40GHz | GPU Intel® Ironlake Mobile
Yes it is required. But you already have one - provided your Windows has been installed in UEFI mode. Make sure by comparing the pictures in this article with what you have: Booting openSUSE on UEFI BIOS with ELILO and Grub2 (part II - Windows dual-boot ). Don’t follow the method decribed there to install openSUSE though. It applied to 12.1.
Absolutely! Fat32. Fat16 used to be possible for Linux, but not for WIndows.
So use it to mount the ESP you must already have. But do NOT format it!
Ohh OK, I didn’t realize that the trick was to use a single ESP for both Windows and OpenSUSE (I was thinking of having two separate boot partitions). This sounds interesting, I’m surely trying this out.
I reinstalled OpenSUSE, this time mounting the Windows-created ESP as /boot/efi, without formatting the partition. Can you allow me a follow-up question? What exactly is the advantage of having a single EFI boot partition that handles both Windows and OpenSUSE, compared to having separate EFI boot partitions? I just didn’t see a difference. In both cases, I select the OS I want to load through the UEFI Boot menu (I have to press F12 on my laptop to get there though), and not through the “other menu” (the menu that allows me to select “Advanced options for openSUSE”…which I guess is the GRUB2 menu?). Windows 7 and OpenSUSE 12.2 both load fine whether or not I choose to use a single ESP.
There is no advantage. You can create another ESP for openSUSE if you like. It might make the installation a little bit more complicated, but not much, I guess.
You can select either openSUSE or Windows in Grub menu (once you have added the correct boot entry for Windows) whether the boot loaders are in the same ESP or in a different one (or similarly in another ESP on another hard drive). You should not need to use the UEFI boot manager. Of course you can do that too.