Menu
According to ADC documentation:
You can access Open Firmware this by holding down Command-Option-O-F at boot time.
However, in reality this does not work on current hardware. Does anybody know if there is a way (through trigger-keys, etc.) to get to an EFI console on contemporary-architecture (i.e., Intel) Macs?
EDIT: I am attempting to set up (and document) various Kernel Debug environments.
In experimenting with the boot-loading mechanisms of OS X, I have come to the following conclusion:
There are at least 3 different architectures:
Open Firmware (PowerPC hardware)
EFI, in which rEFIt works properly
a transitional(?) EFI [32bit?] which is used on early Intel machines, where rEFIt does not work
I had posted this question after encountering this 3rd case, which seems to occur on Core Duo (not Core 2 Duo!) machines: the result being that, once rEFIt is installed, the rEFIt menu DOES correctly get displayed at boot time, however is unusable because it receives no keyboard or mouse input (no USB drivers loaded?) and ultimately always ends up booting into the highest numbered boot partition.
Therefore, in scouring ADC documents and looking for a means to drop into a firmware/EFI console at boot-time, I came across the (somewhat outdated) statement from ADC [see above] and thought that it might be useful to ask on SO if anyone knew of an alternative.
885
Since 2006, Mac computers with an Intel-based CPU use an Intel firmware based on the Extensible Firmware Interface (EFI) Development Kit (EDK) version 1 or version 2. EDK2-based code conforms to the Unified Extensible Firmware Interface (UEFI) specification.
efi is to augment the basic facilities provided by BootROM to the point where the macOS kernel can be loaded with its extensions, largely in terms of providing access to the Mac's hardware through a device tree. When computers were much simpler, all that was needed was basic input and output, in the BIOS.
How You Can Check the EFI Firmware Version. You can check what EFI version your system is running by clicking on the Apple menu and selecting About This Mac > System Report > Hardware.
Instead of Macintosh BIOS, there is UEFI — unified extensible firmware interface — that carries out the same functions as those performed by the BIOS on older Windows PCs. These include initializing the hardware and loading the operating system.
As has already been pointed out, Intel Macs have EFI. However, booting from a CD with rEFIT installed (download the "6.5M ISO disk image", burn to disk using Disk Utility, then reboot holding down the 'C' key), you can select an option to Start EFI shell (its the leftmost icon on the bottom row on my Mac) which may be what you want?
167
The following quote comes from MacForensics.pdf
Apple does not offer any direct tools for accessing EFI. There is no key sequence available to enter EFI upon boot. There are, however, utilities available to access this. One such tool, rEFIt, is available on Sourceforge.net. The link at the time of this writing is http://refit.sourceforge.net/
34
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
