http://piker-alpha.github.io/macosxbootloader/
Pike made this page (upon the suggestion of his Father, Ralf) to help everyone interested get on-board with the same boot.efi, because most public downloads posted in these forums were compiled by @PeterHolbrook for testing purposes, and often in-complete (if they worked, at all).
I've been using 3.1 since (before) release in Yosemite 10.10.5 and El Capitan 10.11.x with complete success: I and many others can personally verify that it works very well.
Everyone has to have a start, somewhere . . . take your time, and enjoy the discovery <smile>
When one boots a modified installer (whether created through the 'createinstallmedia' process to prepare a USB thumb-drive/partition, or with the Jabbawok,
@Hennesie2000 , et al. method I and many others have been using since we first had to fiddle with the guts of the installer to get Mountain Lion installed on 1,1 and 2,1 Mac Pros (hence the "legacy" labeling)), the default "stock" 64-bit boot.efi provided by the Apple installer auto-magically overwrites or replaces the new, modified 32-bit boot.efi, and when a user goes to re-boot the machine to complete the installation, the computer will not successfully boot . . . it's necessary to copy-over Pike's boot.efi to the two aforementioned folders prior to ensure that the second stage of the installer will successfully boot.
You can tell the difference between the different boot.efi's by looking at the size of the file: Apple's boot.efi clocks-in at about 605kb, and Pike's 3.1 boot.efi stands at about 317kb . . . 64-bit vs. 32-bit has to do with the the implementation differences of the UEFI firmware Apple has used to make these things possible (too long to detail, here). Suffice it to say that the 32-bit .efi (originally created by Tiamo in 2009 to get Mavericks up on 1,1 and 2,1 mac Pros, and subsequently adopted/modified by
@Pike R. Alpha) is a way to translate the 32-bit firmware dialogue into 64-bit software language, and enable the kernel to understand what is happening, and not react in Panic as it's immediately teleported from a Tokyo subway train during morning rush-hour, and into a farm just outside Lexington, Kansas, USA during mid-harvest, then back, again (and again (and again ( and again))) <grin>
The boot.efi in /System/Library/CoreServices is locked, and cannot be modified/deleted until it is un-locked.
The boot.efi in /usr/standalone/i386 is un-locked.
You cannot un-lock/replace either from the same OS into which you are currently booted, nor can you replace either with being logged-in to an account without Administrator privileges.
I've booted into Lion to modify the Mountain Lion files, used Mountain Lion to modify the Mavericks files, Mavericks to mod Yosemite, etc. . . . you can even boot into Lion to modify the El Capitan files.
You can also boot into the Recovery environment (Recovery HD), and use Terminal to make the changes.
(as Administrator, in Terminal (names and places have been modified to protect the innocent, and complement the not-so <s>))
To unlock:
Code:
# sudo chflags nouchg /Volumes/Yosemite/System/Library/CoreServices/boot.efi
To replace:
Code:
# cp /Volumes/Other-OS/Place/where/you/have_copied/Pike/s/boot.efi /Volumes/Yosemite/System/Library/CoreServices/boot.efi
Code:
# cp /Volumes/Other-OS/Place/where/you/have_copied/Pike/s/boot.efi /Volumes/Yosemite/usr/standalone/i386/boot.efi
It is not necessary to re-lock the boot.efi in /System/Library/CoreServices to ensure that the installer/OS boots, but you can, if you so choose:
Code:
# sudo chflags uchg /Volumes/Yosemite/System/Library/CoreServices/boot.efi
Never, in all my time.
SSDs are tough, though, and they can take quite a beating, but software is, well, soft . . . <g>
You're welcome,
@Deg. Peace.