[SOLVED] MacbookPro 8,1 13" - Dual boot with Mac OS X #rEFIt

Question

Hi everyone, I want to share my experience and request for help regarding my attempt to install Arch on my MBP 8,1. I can't count the times I've tried to install it this week.
What have I done?
So I followed the Beginner's Guide to aid me in the installation, with some exceptions:
* I used Linux Mint 14 to use GParted. The reason I used it is because rEFIt won't sync the GPT and MBR tables properly when I try and use `mkfs.ext4 /dev/sdaX` inside the Archiso. With Archiso, the filesystem types are considered to be "Unknown" (#wtf no. 1), whereas with Mint that doesn't happen.
* In fstab I had something like:
# /dev/sda4
UUID=c35d9121-a3f1-4cd6-ab53-61fe0f474eee / ext4 rw,noatime 0 1
# /dev/sda5
UUID=390185f6-6d55-430c-a9ba-d3d0b4c7798b /home ext4 rw,relatime,codepage=437 0 2
The wiki mentioned the noatime and codepage flags for the respective partitions and so I complied.
One thing to notice is I have no /boot mount because syslinux apparently doesn't like that.
* Installing syslinux (along with gptfdisk), I issued:
syslinux-install_update -iam
, and reviewed /boot/syslinux/syslinux.cfg like this:
LABEL arch
MENU LABEL Arch Linux
LINUX ../vmlinuz-linux
----APPEND root=/dev/disk/by-uuid/c35d9121-a3f1-4cd6-ab53-61fe0f474eee ro----
APPEND root=/dev/disk/by-partuuid/c35d9121-a3f1-4cd6-ab53-61fe0f474eee ro **still doesn't work, it's not found**
INITRD ../initramfs-linux.img
LABEL archfallback
MENU LABEL Arch Linux Fallback
LINUX ../vmlinuz-linux
----APPEND root=/dev/disk/by-uuid/c35bod9121-a3f1-4cd6-ab53-61fe0f474eee ro----
APPEND root=/dev/disk/by-partuuid/c35d9121-a3f1-4cd6-ab53-61fe0f474eee ro **still doesn't work, it's not found**
INITRD ../initramfs-linux-fallback.img
I used UUID's to avoid the mess on sdaX discrepancies.
Results
* rEFIt correctly shows Arch as a boot option. It boots correctly to Syslinux.
* The kernel load fails due to something like:
Unknown filesystem 'vfat'
... and/or ...
Waiting 10 seconds for /dev/sdaX ...
This stroke me as #wtf no.2. VFAT?? Has anyone experienced this before?
For now this is all I have. I was hoping the community could give me helpful pointers on solving this as I intend to contribute with documentation on this setup in the wiki.
I'll be updating this post with newer information. Thanks for helping!
Last edited by josemota (2012-12-31 18:05:09)

Answer 1

I don't have much experience with SYSLINUX or booting a Mac in BIOS mode, but I can help answer a couple of your questions and offer some alternative approaches....
josemota wrote:
Hi everyone, I want to share my experience and request for help regarding my attempt to install Arch on my MBP 8,1. I can't count the times I've tried to install it this week.
What have I done?
So I followed the Beginner's Guide to aid me in the installation, with some exceptions:
* I used Linux Mint 14 to use GParted. The reason I used it is because rEFIt won't sync the GPT and MBR tables properly when I try and use `mkfs.ext4 /dev/sdaX` inside the Archiso. With Archiso, the filesystem types are considered to be "Unknown" (#wtf no. 1), whereas with Mint that doesn't happen.
This issue is a limitation of the "gptsync" program that's included with rEFIt, not with rEFIt itself. It's also not caused by mkfs; gptsync doesn't even look inside the partitions, AFAIK. Instead, it looks at partition type codes. It understands just a few of them, including the one that all but the very latest versions of libparted use on Linux filesystem partitions. The trouble is that the libparted developers long ago "borrowed" that code from Windows, but they shouldn't have done so. That's being corrected, and gdisk can use the correct code for Linux ("8300" in gdisk). In the future, libparted will use this code, too; the support is already present but isn't yet widely distributed. You could have set the type code to "0700" in gdisk from Arch and gptsync would have worked.
You may be interested to know that gdisk can do the same job that gptsync does, and gdisk can do so much more flexibly. You can read more in the gdisk hybrid MBR documentation. Be aware that hybrid MBRs (which is what gptsync creates) are ugly and dangerous hacks. Sadly, they're necessary to dual-boot Windows and OS X on Macs, but you may be able to dual-boot OS X and Linux without a hybrid MBR. The trick here is to install an EFI boot loader for Linux rather than a BIOS boot loader for Linux. Macs use EFI natively, so this is the superior way to get started, at least theoretically.
The Arch wiki has a number of pages on EFI issues, such as:
https://wiki.archlinux.org/index.php/Un … _Interface
https://wiki.archlinux.org/index.php/UEFI_Bootloaders
https://wiki.archlinux.org/index.php/GRUB_EFI_Examples
The main problem with booting a Mac in EFI mode is that some systems won't activate all their hardware in this way, so with some models you can end up with a network adapter or video display or sound that doesn't work. Other models are fine, though; you'll just have to give it a try and see if it works.
Personally, I think the best way to do it is to use the kernel's EFI stub loader in conjunction with an EFI boot manager like rEFInd or gummiboot. Both are available as Arch packages, but it's better to install from OS X, and that process is much better documented for rEFInd than for gummiboot (although you could adapt the rEFInd documentation for gummiboot, if you liked). rEFIt can work, too, but only if the kernel includes built-in command-line options and is renamed with a ".efi" extension. These are awkward requirements, and since rEFInd is a continuation of rEFIt development, there's not much point in trying to get rEFIt to do the job.