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Booting Linux inside a MacBook using grub and EFI

What follows applies only to MacBooks that contain an Intel CPU (and not to the older PowerPC models).
There are two ways to boot a GNU/Linux operating system installed inside an Apple MacBook.

Use an emulated BIOS environment. This is usually called boot camp and is what Apple designed so that users could also install Windows alongside the Mac OS, and setup their MacBook for a dual-boot.
Use the EFI. MacBook do not employ a BIOS to boot the system, but they use EFI. The latest GRUB has an EFI mode, so that it can be used to boot Linux directly from EFI.

The following instructions explain what I did to boot Debian and Ubuntu in my MacBook 5.1 using EFI. You should also read:

http://grub.enbug.org/TestingOnMacbook (alas, in Sep 2011, this is down, so see in https://help.ubuntu.com/community/UEFIBooting)
see also 538730
the debian wiki
http://www.rodsbooks.com/ubuntu-efi/index.html

(but note that they are outdated and/or different than my experience, in many points: e.g. in my experience the Nvidia 3D acceleration works fine, contrary to what the Debian wiki says! and the virtual terminals are OK when using nouveau).
Note that modern Intel CPUs can run both 32bit and 64bit code (and that is called i386 and amd64 in Debian and Ubuntu). In older MacBooks EFI is started in 32bit mode, in newer ones in 64bit mode. The version of grub-efi that you install should be of the same type. See into http://grub.enbug.org/TestingOnMacbook for details. Indeed nowadays Debian contains two packages grub-efi-ia32 and grub-efi-amd64 for that reason. For the MacBook 5.1 , I used the amd64 version.
According to some sources, the linux kernel that is then booted should again be of the same type, otherwise it will not be able to dialog with EFI correctly. I personally have booted both without noticing problems.
I was able to boot succesfully the following O.S.:

Debian/squeeze/i386
Debian/wheezy/i386
Debian/wheezy/amd64
Ubuntu/lucid/amd64

By "succesfully" I mean that all hardware works fine, including

built-in camera, (in Ubuntu/lucid and Debian/wheezy I did not even need to exctract the firmware from the Apple drivers!)
sleep (but rarely it may hang on wakeup),
wireless (note that in Debian/squeeze you need to install updated drivers for the wireless card ; in Debian/wheezy, with kernel 3.0, it works right away).
video (works out of the box, I did not need to extract display settings and timings from the Mac OS)
display backlight (works out of the box in Debian/wheezy, when X uses nouveau drivers, and in Gnome you can use the two keys F1 F2 to adjust it)

booting Debian (and Ubuntu) into a MacBook 5.1 using grub2-efi

Inside the Mac OS, install the program refit: this will show a boot menu where you may then choose to chain-boot into grub. Also, prepare partitions. Then install Debian or Ubuntu in some partition. (I am not providing further instructions on this: see the debian wiki. AFAICR the first time, some years ago, I installed Debian/Lenny using a CD and boot-camp mode, then I used 'debootstrap' to install all the rest).

Install needed packages and generate the grub.cfg

 # apt-get install grub-efi-amd64
 # update-grub

mount EFI partition

 # mkdir /efi
      # mount /dev/sda1 /efi

if you have any previous working EFI grub install, from here on you may want to substiture /efi/efi/grub with a different directory. (Note that by the rEFit menu you may select any of your GRUB instances).
create the directory for the grub instance
```
 # mkdir /efi/efi/grub
```
cd into this directory for the following commands
```
 # cd /usr/lib/grub/x86_64-efi
```
copy all stuff that http://grub.enbug.org/TestingOnEFI tells to copy
```
 # cp *.mod fs.lst command.lst /efi/efi/grub
```

newer versions of grub (Debian jessie or later) search modules in a different directory

 # mkdir /efi/efi/grub/x86_64-efi
 # cp *.mod fs.lst command.lst /efi/efi/grub/x86_64-efi

create EFI image

 #  grub-mkimage -d . -O x86_64-efi \
   -o /efi/efi/grub/grub.efi    -p /efi/grub \
    part_gpt hfsplus fat ext2 normal \
          chain boot configfile linux multiboot \
       loadenv gzio echo test search

copy /boot/grub/grub.cfg into /efi/efi/grub/ and possibly edit it to load the correct video driver, in my case
```
function load_video {
  set debug=fb
  insmod efi_gop
  #insmod vbe
}
```
or otherwise use efi_uga on older MacBooks. (Moreover, if your root partition is crypted, you will need to copy the linux kernel and initrd in a non crypted partition, say /efi/linuxboot, and modify /efi/grub/grub.cfg consequently).
In Debian/squeeze it seems that nouveau drivers do not work in efi mode, blacklist them: create a file /etc/modprobe.d/efi_boot.conf containing just
```
blacklist nouveau
```
In Debian/wheezy and Ubuntu/lucid , they are fine.
In Debian/squeeze you may need to load some modules quite early (in particular if you have a crypted root partition: otherwise the keyboard will not work at the moment when the initrd will ask you the password). To this end, append to the file /etc/initramfs-tools/modules these lines:
```
#as suggested by http://grub.enbug.org/TestingOnMacbook
fbcon
#and I would further add
hid_apple
hid
applesmc
input_polldev
#moreover  Vladimir 'phi-coder/phcoder' Serbinenko
#told me also to add 
uhci_hcd
ehci_hcd
ohci_hcd
```
then regenerate the initrd
```
# update-initramfs -u
```
Again, it seems that Debian/wheezy does not need those (I have a crypted root partition, and I can enter the password without problems).
Using NVIDIA. The nouveau driver in Debian/wheezy works fine, but does not provide (yet, at Sep 2011) any GL acceleration. So I installed the nvidia stuff. There are two problems with the nvidia stuff:
- once the X server starts, if you type ctrl-alt-F? to go back to a text consoles, it will be all pitch black;
- the screen backlight cannot be adjusted (but, warning! if you change it, and you go into sleep mode and then out, then it will be changed: so if you dim it too much, and you sleep in/out, your screen will be pitch black!)