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 Appleā€“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 19:12.
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