[syslinux] isolinux: Generate GPT and Mac bootable images

[Gert Hulselmans]

Matthew Garrett wrote:
> On Fri, Aug 05, 2011 at 02:48:00PM -0700, H. Peter Anvin wrote:
>
>> Hmmm... as I recall, you can't put a bunch of padding before the xorw
>> %bp, %bp... some broken BIOS requires that at offset 0... presumably
>> some specific M$ MBR had that instruction first, and someone decided to
>> use it as a magic signature.  Sigh.
>
> Well that obviously makes things harder - we need to put ER at offset 0.
> Have you got an example of one of them? I'll try to chase it down and
> see if there's anything that can be done.
>
> --
> Matthew Garrett | mjg59 at srcf.ucam.org
>

It is a bit explained in post #6 at http://reboot.pro/10503/

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I have an Acer Travelmate and had the known “Unregistered Exception
Handler” error at boot time.

Short Explanation:
The laptop starts up bios and when the bios whats to boot from any
media(not even your harddisk) the exception is thrown.

Reason:
The Diskcryptor MBR starts with 0xeb(jmp). The original M$ mbr starts with
0x33(xor ax,ax).
Some bioses(like mine) try to detect if a drive has a MBR or if it is a
removable drive without MBR.
Very simple here:
Sector0,Position0==0x33 => MBR => normal partitioned harddisk.
Sector0,Position0==0xeb => Boot Sector assumed => emulate a hard disk(this
is what makes usb-sticks without mbr bootable as harddisks, and makes my
acer crash)
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- Gert Hulselmans