Normally UEFI creates ACPI tables that have some similarity with device trees. PowerPC OS X probably expected a device tree provided by Open Firmware so when t

Normally UEFI creates ACPI tables that have some similarity with device trees. PowerPC OS X probably expected a device tree provided by Open Firmware so when they switched to EFI they probably added that boot.efi shim so the kernel didn't have to change much. It doesn't really matter whether the bootloader or the kernel enumerates hardware.