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#1 2013-06-14 10:11:30

centos
Member
From: Ostrava, Czech Republic
Registered: 2009-01-09
Posts: 65

[Solved] Arch + W8 dual boot, UEFI, partitioning question

Hello,
I'm buying new laptop with preinstalled W8 (Lenovo E430) and I'm planning to dual boot. I've read Beginner's guide, Installation guide, searched forum, etc., but I'm still unsure how to deal with creating partitions for Arch while keeping Windows.

From the Beginners' Guide:

If you are intending to follow the advice to create a GPT partition table then you need to choose "Advanced" and then select "gpt" from the drop-down menu. This cannot be done if you have a pre-existing Windows installation on the drive which you wish not to destroy.

and from the Partitioning:

To dual-boot with Windows, one must use MBR.
A special exception to this rule: dual-booting Windows 64-bit using UEFI instead of BIOS, one must use GPT.

My W8 will be 64bit and also is Arch.

So, my question is. When I shrink W8 partition and create free space for Arch, do I have to choose 'gpt' option (2nd quote) or not (1st quote) for formatting? Or am I reading it totally wrong?
I would give it a try, but that destroying thing kind of scares me.

Last edited by centos (2013-06-18 19:24:58)

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#2 2013-06-14 10:52:01

TheSaint
Member
From: my computer
Registered: 2007-08-19
Posts: 1,380

Re: [Solved] Arch + W8 dual boot, UEFI, partitioning question

Short description, as I did:
Start a live distro, or one installed on a separated media. If you find difficult to boot into USB installation, you might find to disable some parameter in the BIOS setting to allow booting from non EFI media.
If you have already W8 installed you might proceed to shrink some partition, except that containing ????.efi file.


do it good first, it will be faster than do it twice the saint wink

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#3 2013-06-14 11:12:44

centos
Member
From: Ostrava, Czech Republic
Registered: 2009-01-09
Posts: 65

Re: [Solved] Arch + W8 dual boot, UEFI, partitioning question

Thanks, but the question actually is what to do after shrinking. Appereantly there are two different options for partitioning - gpt and mbr. I believe that those two wiki quotes in first post are mutually exclusive. So, for example, if I boot to gparted live CD, shrink W8 partition and make partitions for Arch while not changing anything else (gparted default setting) and format these partitions to ext4, will it work or am I gonna lose W8?

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#4 2013-06-14 11:35:19

TheSaint
Member
From: my computer
Registered: 2007-08-19
Posts: 1,380

Re: [Solved] Arch + W8 dual boot, UEFI, partitioning question

Sorry I had an interruption and I got to leave.
You should get information by issuing fdisk -l which will tell you how the hard disk is partitioned. Unless you chosen to partition the HD yourself, mostly the layout would be a GPT.
I shrunk my W8 partition and I made other 3 ( or 4, I can't remember), therefore I kept the original GPT, or in such case I could opt for GPT, because there are more than 4 primary partitions. Also W8 will work first for primary partitions.
If you have a blank HD, it's advisable to let W8 do its disasters lol lol then proceed with Arch installation.
When you've done it, you might try to get into the installation. That was my difficulty, but I read GRUB and UEFI wikis.
I was difficult to write the efibootmgr setting, because is only possible only when the kernel can load the efivars.


do it good first, it will be faster than do it twice the saint wink

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#5 2013-06-14 15:57:22

srs5694
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From: Woonsocket, RI
Registered: 2012-11-06
Posts: 719
Website

Re: [Solved] Arch + W8 dual boot, UEFI, partitioning question

The wiki quotes you've presented make it look like the wiki was created with an MBR/BIOS assumption and then poorly edited to incorporate GPT/EFI information. The rules, presented in a more cohesive way, are these:

  • Windows ties its partition table type to the computer's firmware: under BIOS, Windows requires MBR; and under EFI, Windows requires GPT.

  • Linux is more flexible: It can use either MBR or GPT under BIOS. In theory, Linux can use either MBR or GPT under EFI, although many EFIs seem to require GPT, so it's best to stick with GPT on EFI-based computers.

  • When dual-booting, Windows is the limiting factor when it comes to partition table type.

  • Most EFIs include a Compatibility Support Module (CSM), which enables them to boot BIOS-based OSes. The CSM can usually be enabled or disabled in the firmware setup utility, although the details of how to do this vary from one implementation to another.

  • Computers that ship with Windows 8 pre-installed almost always use EFI, and therefore GPT.

  • Converting from MBR to GPT or vice-versa is possible with GPT fdisk (gdisk, cgdisk, or sgdisk), but this requires re-installing the boot loader for any already-installed OS(es). If Windows is one of those OS(es), it's probably not worth the effort.

  • GParted and parted can convert from MBR to GPT or vice-versa only by destroying existing partition entries, so you should use these tools to make such a change only on a blank disk or if you intend to lose all the existing partitions.

Since you (centos) say you're installing to a computer with a pre-installed Windows 8, you've almost certainly already got an EFI/GPT setup. Under these circumstances, you won't be choosing a partition table type unless you want to completely wipe that installation and install both OSes fresh. GParted will detect the partition table type and work with it automatically; you should not select the option to create a new partition table, which your first quote (partially) describes. You should, however, be sure that you install Arch in EFI mode and that you install an EFI-mode boot manager and/or boot loader, rather than a BIOS-mode version of GRUB. Getting an EFI-mode Windows and a BIOS-mode Linux to coexist is possible, but awkward. Converting a BIOS-mode Linux installation to boot in EFI mode is also possible, if you mistakenly install in BIOS mode; but it's usually easier to install in EFI mode to begin with. There are lots of threads here on EFI-mode Arch installations, as well as information in the Arch wiki on this topic. Unfortunately, EFI is still new enough that there are still a lot of kinks to be worked out, both in specific firmware implementations (many of them are buggy) and in OS support (which is still not as mature as is BIOS support).

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#6 2013-06-14 19:51:23

centos
Member
From: Ostrava, Czech Republic
Registered: 2009-01-09
Posts: 65

Re: [Solved] Arch + W8 dual boot, UEFI, partitioning question

Thank you! In couple days I'll have that laptop and will hopefully mark this as solved.

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#7 2013-06-16 13:47:44

TheSaint
Member
From: my computer
Registered: 2007-08-19
Posts: 1,380

Re: [Solved] Arch + W8 dual boot, UEFI, partitioning question

I'd like to add...... In certain case the BIOS is set with security options and require some particular credentials to boot foreigner media. I far as I could find, in my installation I had to disable the security option, because I hadn't those credentials.

Last edited by TheSaint (2013-06-16 13:49:03)


do it good first, it will be faster than do it twice the saint wink

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#8 2013-06-18 19:24:10

centos
Member
From: Ostrava, Czech Republic
Registered: 2009-01-09
Posts: 65

Re: [Solved] Arch + W8 dual boot, UEFI, partitioning question

Hi, so I did't change anything, only shrinked win partition and created three new (swap, system and data). Working fine. Biggest issue was to boot to GParted GUI smile Thanks again.

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