Boot-132

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Boot-132 is a bootloader provided by Apple for loading the XNU kernel.

The loader was used in the Apple Developer Transition Kit PC rented to software developers during the Apple–Intel transition. This bootloader is not used on Intel Macs, instead boot.efi is used.

Source code for Boot-132 was released along with the XNU kernel in the 10.4.8 set of tarballs. Boot-132 was used with the last version of OS X for the DTK systems. Previous releases used boot-122 or earlier versions of Apple boot.

Contents

[edit] Boot stages

Boot-132 consist of three boot stages: boot0, boot1 and boot2.

  • Boot stage 0 is a short assembly program (less than 446 bytes) located in the Master Boot Record of a MBR partitioned disk. Boot0 assumes the presence of a BIOS in the system and calls interrupt 0x13 to access low-level hard disk read and write services. The Apple version of boot0 only supports MBR partitioned disks. Support for GUID partition table is added to Chameleon versions of the code.

[edit] Boot-dfe

Boot-dfe is a modified version of Boot-132 created by David Elliott in 2007. The boot-dfe loader is started by another bootloader, typically GRUB, or in the case of booting from a CD, a patched version of ISOLINUX. The interface between the two bootloaders is defined by the GNU Multiboot Specification. The boot-dfe loader populates the struct boot_args structure and passes it on the the XNU kernel. (See OS X boot process.).

The latest versions of boot-dfe are able to load additional kernel extensions to the XNU kernel as an initial ramdisk (initrd). The extensions can be stored in an HFS or HFS+ partition in a APM, GPT, or MBR partitioned volume. The ramdisks are supplied to boot-dfe by the multiboot loader in the form of Multiboot modules.

[edit] The Boot-132 method

The Boot-132 method is a method of installing Mac OS X Leopard or Snow Leopard on a PC from a retail DVD. This was made possible by the version of boot-dfe released in June 2008

To boot from an OS X retail disk first boot from the boot-dfe CD. When Darwin boot prompt appear, eject CD and replace with Mac OS X Retail DVD and select it from the menu. After installation, boot from the hard disk the first time using the boot-dfe CD and install the .kext needed.

[edit] Chameleon

The Chameleon bootloader is derived from Apple's boot-132. It adds David Elliott's fake EFI implementation.

[edit] References

[edit] External links


This page was last modified on 15 October 2011, at 20:12.
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