Mac (EFI) USB booting

[Daire Byrne]

Hi,

I have been trying to get Mac booting working but I am struggling to jump the first hurdle
- namely having the Mac recognise the USB drive as a bootable device. I have used ALT on
boot to list the bootable drives on both a Mac Mini and a PowerMac desktop machine but
neither recognise a USB stick created with livecd-tools. In fact after booting from the
drive MacOSX informs me that the drive isn't initialised and wants me to format it.
Checking the partitions in Linux they are laid out as expected with a bootable EFI
partition vfat formatted.

I gave up on EFI booting and even tried a classic MBR install with rEFIt but still the USB
drive is never detected. Is there another trick I'm missing here or does USB booting
only work on a very small subset of Intel Mac models? The recent EFI+MBR work looks
interesting but like I said I can't even get that far.

Regards,

Daire

[Jeremy Katz]

On Monday, January 19 2009, Daire Byrne said:
>  I have been trying to get Mac booting working but I am struggling to
> jump the first hurdle - 
>  namely having the Mac recognise the USB drive as a bootable device. I have used ALT on
> boot to 
>  list the bootable drives on both a Mac Mini and a PowerMac desktop machine but neither 
>  recognise a USB stick created with livecd-tools. In fact after booting from the drive
> MacOSX 
>  informs me that the drive isn't initialised and wants me to format it. Checking the
> partitions 
>  in Linux they are laid out as expected with a bootable EFI partition vfat formatted.
PowerMacs (PPC) are an entirely different beast and there's not really
been any work done on getting them booting off of USB.

For the x86 based Macs, it can work, but it's definitely far from just
working everywhere right now.  The first question is if your machine is
32bit or 64bit EFI as we require matching x86 vs x86_64, respectively,
based on that.  Most of the original Core Duo stuff is 32bit EFI, the
newer is 64bit.  If you're using a 64bit EFI machine, right now, you're
out of luck -- the kernel even in Fedora 10 was broken with 64bit EFI :(

For 32bit, it _should_ work with Fedora 10.  But I don't think I've
actually tested it on one of the Minis, and sadly, the Apple firmware
has been notoriously bad about being buggy :)
 
>  I gave up on EFI booting and even tried a classic MBR install with
> rEFIt but still the USB drive 
>  is never detected. Is there another trick I'm missing here or does USB booting only
> work on a very 
>  small subset of Intel Mac models? The recent EFI+MBR work looks interesting but like I
> said I can't 
>  even get that far. 
I never managed to get rEFIt to boot off of an MBR-based USB device.
Some people said they did, but I have no clue what they did to do so :)

Jeremy

[Stewart Adam]

On 1/19/09 1:19 PM, Jeremy Katz wrote:
>  PowerMacs (PPC) are an entirely different beast and there's not
> really
>  been any work done on getting them booting off of USB.
>
>  For the x86 based Macs, it can work, but it's definitely far from just
>  working everywhere right now.  The first question is if your machine is
>  32bit or 64bit EFI as we require matching x86 vs x86_64, respectively,
>  based on that.  Most of the original Core Duo stuff is 32bit EFI, the
>  newer is 64bit.  If you're using a 64bit EFI machine, right now, you're
>  out of luck -- the kernel even in Fedora 10 was broken with 64bit EFI :( 
I
didn't think of giving it a on one of the older MacBook machines - I'll do 
that sometime soon. It could be a bug in the 64bit firmware, but I have 
tried using a i386 grub EFI image and i386 kernel on my early 2008 MacBook 
Po, but same symptoms as booting 64bit kernels.

>  For 32bit, it _should_ work with Fedora 10.  But I don't think
> I've
>  actually tested it on one of the Minis, and sadly, the Apple firmware
>  has been notoriously bad about being buggy :) 
Yup - the MBR USB bug seems to one of
the more annoying ones :/

> > I gave up on EFI booting and even tried a classic MBR install
> with rEFIt but still the USB drive
> > is never detected. Is there another trick I'm missing here or does USB booting
> only work on a very
> > small subset of Intel Mac models? The recent EFI+MBR work looks interesting but like
> I said I can't
> > even get that far.
>
>  I never managed to get rEFIt to boot off of an MBR-based USB device.
>  Some people said they did, but I have no clue what they did to do so :) 
There was
so many reports with different results... If what I read was 
correct, it looks like some of Apple's older firmware didn't have the USB 
MBR booting bug, but the newer firmware (post BootCamp 2.0 I think) does. So 
really, anyone that runs Software Update or buys a Mac with the new BootCamp 
already installed doesn't have the ability to boot from USB drives with an 
MBR in rEFIt... Instead, rEFIt switches and uses the internal drive's MBR.

Stewart