Win8/12.04 dual-boot and EFI newbies: Please clarify and correct ...

[Bucky Ball]

Hi all,

Helping a friend install Ubuntu 12.04 LTS 64bit to a Win8 hard drive for a dual-boot. Friend created a partition for Ubuntu months ago and finally we started playing around with it new year's eve. Booted from a 12.04 LTS disk and it worked like a charm on friend's machine.

Friend did attempt an install a couple of days later, but reports that he stopped installing when there was no sign whatsoever of his Windows install. Stroke of luck there as I believe that is an EFI issue that would have wiped Win8 if he'd have continued. Anyway, off-topic.

He's keen to get it installed, I'm not there and no EFI expert, so I have been researching it over the last few days and was hoping the community could help to clarify and correct my findings so I can pass them on.
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1/ Win8 is self-installed, not a pre-install, so I'm presuming there is no issue about secureboot and we can disregard that and continue.

2/ The Win8 partition is marked 'EFI' in the BIOS. In this case, I would have thought there would clearly be a small partition marked 'EFI' in Win disk management, but;

3/ Win8 Disk Management (think that's it) shows there's a 350mb partition on Win8 disk, but it has no label. Could that be an EFI partition? Is there a way of telling?

4/ The BIOS says the disk is EFI, so:
- We need to boot the optical drive/Ubuntu EFI and if so how? I've read that if Win8 is installed EFI then Ubuntu must be installed EFI.

5/ We will be partitioning manually using 'Something Else' so:
- If there IS no existing EFI partition, I presume we need to create a 500mb partition that comes before /, /home, /swap or any other *buntu partitions, and Ubuntu will know what that is without us providing a mount point (/boot/efi) as the disk itself is being booted in EFI mode?

(#5 has me a bit confused; what's the exact procedure for creating this partition? I'm aware Ubuntu doesn't show a mount point for /boot/efi once it is created.)
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All thoughts, advice and corrections greatly appreciated. As you can probably see, I am attempting to create a working model specific to this situation from the many pages of information I've seen to pass on to friend for a successful install without me being there to experiment.

TIA.

PS: It's been fun learning about EFI as I knew pretty much absolutely zilch about it on Wednesday!

[varunendra]

I'm sure you have already read this wiki : https://help.ubuntu.com/community/UEFI
Adding only what I know (or rather have 'learnt' by seeing threads here) -

3/ Win8 Disk Management (think that's it) shows there's a 350mb partition on Win8 disk, but it has no label. Could that be an EFI partition? Is there a way of telling?

I believe it must be a FAT32 (or probably FAT16) partition for EFI data, and if EFI is enabled in the BIOS, it must be the EFI partition. Maybe you can confirm whether it is the EFI partition or not by looking at its contents.

4/ The BIOS says the disk is EFI, so:
- We need to boot the optical drive/Ubuntu EFI and if so how? I've read that if Win8 is installed EFI then Ubuntu must be installed EFI.

I think the wiki page I linked above confirms that. If EFI is enabled in BIOS, simply boot with the 64 bit version of Ubuntu Live DVD and it will automatically boot into EFI mode.

Beyond this, I'm afraid I can only confuse you further. So let's wait for those having first hand experience of EFI.

[Bucky Ball]

Thanks for that. I'm on the right track, I think.

[oldfred]

See all the links in my signature. Maybe be too much but most info you need it there. Lots of special cases.

Only one efi partition per drive.
UEFI & BIOS/CSM/Legacy boot modes are not compatible. Once you boot in one mode you cannot switch at grub menu. And how you boot install is how it installs for both Windows & Ubuntu.
Boot-Repair can convert a Ubuntu install from BIOS to UEFi or vice-versa by installing the correct version of grub2.

Windows only boots from gpt partitioned drives with UEFI.
Windows and Ubuntu only boot with BIOS from MBR(msdos) partitioned drives.
Ubuntu will boot in either UEFI or BIOS from gpt partitioned drives.

Secure boot will depend on hardware. Not seen any new systems with secure boot that were not pre-installed Windows, but I would expect at some point all new UEFI systems will have that "capability".

But fastboot is always an issue with Windows and dual booting. It is hibernation to speed boot.

[Bucky Ball]

The link in your signature has been the launch point for me getting my head round this and the info I put together in the first post is from 'scraping' those pages for the bits appropriate to this particular setup. Thanks for that and for putting things in a nutshell in your post.

Sounds like I have it just about right for the setup in question then. The disk is booting in EFI mode (so I guess this is GPT automatically or that needs to be set separately?) and the Win8 partition is marked 'EFI' in BIOS, so as long as we leave the disk booting in EFI mode to install Ubuntu (and choose 'Something Else' at the partitioning section) all good.

[oldfred]

Glad to get some feed back that how-to is helpful.

Only if you partition in advance to a blank or previously MBR drive that you want to erase would you have to specify gpt. Gparted defaults to MBR.

The installers for both Windows & Ubuntu will use gpt if installing in UEFI mode. Not sure if drive is MBR and you try to install Ubuntu in UEFI mode. If drive is gpt and you install Windows in BIOS mode it converts to MBR, but leaves backup gpt table causing issues with any Linux tools that are a bit smarter and see both MBR & gpt.

[Bucky Ball]

Just to clarify, oldfred, inspired by some info you posted on another thread ...

Win8 has to be installed in EFI and consequently that means GPT> the four partitions per drive rule does not apply with GPT. So, you mention on the other thread that rather than four partitions, with GPT the maximum is 128, primary or extended. Have I got this right? Sure makes life easier if that is the case.

[oldfred]

With gpt you only have one partition type essentially equivalent to primary, and the limit is 128 partitions with default partition table size.

I understand that a user can change partition table size so you can have even more than the default 128 partitions, not sure if I could manage a system with that many. I have 10 or 15 little ones on my larger drive and am lost. Back to hard copy print outs to know what is where.

https://wiki.archlinux.org/index.php...antages_of_GPT
GPT Advantages (older but still valid) see post#2 by srs5694:
http://ubuntuforums.org/showthread.php?t=1457901

I started using gpt with 10.10 just to learn about it on one of my smaller drives. And only started learning about UEFI as I was planning a new system. I actually first looked into UEFI when building my new (current) system in 2006, but only server motherboards had it and they were over $3000. Still not built new system as two years ago I added SSD and old system still runs well for what I do.

[Bucky Ball]

Off topic, but yea, I'm about to buy this I think:

http://www.msy.com.au/product.jsp?productId=11451

So it is correct that when you install Win8 it will install itself EFI and create its three partitions and EFI partition automagically? It needs the disk to be booting in EFI to install?

I heard from my friend and he's had a bash at it, but screwed it up. He's been busy so hasn't checked if Win is still there, but sounds like he was having problems with Ubuntu recognising the Win partition so he switched off EFI and installed that way. Think he can boot Ubuntu but not Win now.

I'll have more detail about that on the weekend but just preparing for the eventuality of reinstalling Win8 and learning about how it operates.

[oldfred]

Often the Ubuntu installer does not see Windows because fast boot or always on hibernation is on. Or chkdsk is needed. Or it is an Ultrabook with RAID. Or user reinstalled Windows in BIOS mode and drive is half MBR and have gpt.

And some go back and reinstall Ubuntu and now it erases drive unless Something else chosen.
But if Ubuntu originally installed in BIOS/CSM/Legacy mode, then it may only boot Ubuntu as it is only BIOS mode. But from UEFI menu with UEFI one (not even even secure boot on) it should boot Windows. And boot-Repair will convert BIOS Ubuntu install to UEFI by uninstalling grub-pc(BIOS) and install grub-efi(UEFI). But is Windows is overwritten it often overwrites entire drive. So unless user has backup or DVD copy of recover partition, it is a big problem if they still want Windows. Some vendor offer recover DVDs for nominal charge or you have to purchase full Windows install.