How to boot from a disk image that's been copied to a partition?

January 5, 2006 1:54 AM

I'm trying to boot the Mac OS X Intel installer CD from a hard drive partition (I have no DVD drive). I used dd to write the ISO to /dev/sda6, and I configured grub to boot from it. But grub won't boot it.

First, I created a new (logical) unformatted partition of 20 GB at /dev/sda6. I ran 'dd if=macosx.iso of=/dev/sda6' and then edited grub to boot like:

title MacOSX-Intel
rootnoverify (hd0,6)
chainloader +1
(I've also tried hd0,5 and hd0,7 and others, so that's not the problem.)

When the grub screen comes on, I try to boot the MacOSX-Intel entry. Here's the error I get with the corresponding entry from the grub manual.

13 : Invalid or unsupported executable format
This error is returned if the kernel image being loaded is not recognized as Multiboot or one of the supported native formats (Linux zImage or bzImage, FreeBSD, or NetBSD).

How can I get this bootable disk image to boot from a hard drive partition instead a DVD? I have the full set of Unix tools at my disposal, and I have no problem mucking around at a low level if I need to.

posted by jbb7 to computers & internet (5 answers total)

I'm not sure if it's the same for DVDs, but CDs usually store bootable information in El Torito format. This is stored within the ISO image, but certainly isn't the same as a normal MBR or partition boot block. So it's not surprising that writing the raw ISO to a partition didn't result in anything bootable.

If it's a regular ISO image, with a sane El Torito boot image, you might try an extractor (I wrote this one, there's another called BBIE for Windows):

http://pangaea.dhs.org/~chahast/etex.pl

to extract the boot data. From there... I guess you could dd it to the first part of the partition, or you might have more success putting it on a floppy.

Then, if something does boot, it'll probably be looking for all the info to be stored on an optical drive. Which it isn't.

Maybe you can put in another hard drive, and write the ISO data to the raw device (/dev/hdx, not /dev/hdx1)?

I guess the obvious question is... why can't you find/borrow/steal/purchase a DVD drive?
posted by lalas at 2:48 AM on January 5, 2006

Thanks for the help. To answer your question, this computer is a tiny one with no expansion, so adding a DVD drive isn't possible.
posted by jbb7 at 2:56 AM on January 5, 2006

It doesn't have any expansion at all? If it's got PCI, you can add a cheap IDE or USB controller. If it's got USB, and a relatively modern BIOS, you can probably boot off a USB DVD drive. They sell IDE/USB enclosures for around $20.

But that doesn't guarantee the installer would recognize it... straight IDE would be safer in that regard.

OK, time for sleep.
posted by lalas at 3:03 AM on January 5, 2006

I don't know a thing about OS X. But the ISO format is meant for CDROMs/DVDROMs, but it is not a filesystem as you would find it on the HD. From the grub manual the filesystems that are supported are: BSD FFS, DOS FAT16 and FAT32, Minix fs, Linux ext2fs, ReiserFS, JFS, XFS, and VSTa fs.

Since the function of the boot loader is rather simple, I'd suggest using something else that can boot from ISO-image-on-HD. Or get a DVD-ROM drive, they're like $20 these days.
posted by Rhomboid at 3:19 AM on January 5, 2006

Now correct me if I'm wrong, but all of the developer systems from Apple do have DVD drives. The developer license specifically limits your ability to install the OS on non-developer hardware and if you were a legit user you'd be seeking support in the forums at Apple.com rather than asking here in violation of your NDA. That would mean that you are asking here specifically for support for a warezed copy of OSX for intel. Now, I make no moral judgement about this...Ok, I do...but it just seems that AskMefi isn't the place for asking for help for such things.
posted by shagoth at 7:05 AM on January 5, 2006