iBoot

iBoot is the name of Apple’s bootloader. Its components are implemented in both hardware and software, and the term iBoot may refer to one of the following, which all have iBoot- in their version strings:

• Bootrom (SecureROM), the hardware implementation
• Any of the four variants of the software implementation:

• iBEC (iBoot Epoch Change; called iBootStage2 in iOS 10 and later)
• iBoot second-stage loader (often called simply iBoot)
• iBSS (iBoot Single Stage; called iBootStage1 in iOS 10 and later)
• LLB (Low Level Bootloader or iBoot first-stage loader in A9 or earlier)

The software implementations are built from the same source, but with different build parameters, as shown in the comparison table below.

Product	Modules							Text bank	Options
	BOOT	CONSOLE	DFU	DISPLAY	FILESYSTEM	FIRMWARE	RECOVERY
iBoot	Yes	No	No	Yes	Yes	No***	Yes	sdram	recovery, boot, filesystem, restore_strap
iBEC	Yes	No	No	No	Yes	No***	Yes	sdram	recovery, boot, filesystem, restore_boot
iBSS	Yes*	No**	Yes	No	No	No***	Yes*	sram	dfu, restore_strap, recovery*, boot*, restore_boot*, console**
LLB	No	No**	Yes	No	No	Yes	No	sram	dfu, restore_strap, console**

* Not included in special development builds
** Included in special development builds
*** Included through the BOOT module, which consists of the submodules FIRMWARE, NVRAM, RAMDISK and SYSCFG.

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