TweetFollow Us on Twitter

Apple's Transition from Open Firmware to Extensible Firmware Interface

Volume Number: 23 (2007)
Issue Number: 05
Column Tag: System Technologies

Apple's Transition from Open Firmware to Extensible Firmware Interface

By Criss Myers

Preface

In January 2006, Apple introduced Intel Architecture based Macs. They took this hardware move as an opportunity to also upgrade their choice of firmware. Their previous firmware, Open Firmware, was not in itself a bad choice, being far more advanced than the IBM PC BIOS that Windows computers use. There is, however, a better firmware choice that offers improvements on Open Firmware, called Extensible Firmware Interface, EFI, developed by Intel. When Apple looked for a successor to their PowerPC Processors, they found a complete hardware package from Intel. They got the latest CoreDuo and Xeon Processors, as well as advancements in boot firmware and disk partitioning. Since Apple offers an integrated package, this enables them to control all aspects of the computer system from processors to boot firmware to operating system. This also enabled them to make a smooth transition from the PowerPC, Open Firmware, APM and their 32bit OS, to Intel processors, EFI, GPT and 64bit Tiger OS X. Anyone using these 2 systems will not notice any difference apart from their performance. In this article we will take a brief look at Open Firmware and then explain what EFI is, its history, and what this means for Apple's future as well as that of the PC market in general.

Open Firmware

Apple's PowerPC Macs, post-NuBus, used a boot firmware called Open Firmware. Open Firmware, also called OpenBoot, was developed by Sun Microsystems and is used in Sun's Sparc work stations and servers, IBM POWER systems and PegasosPPC systems and is available under a BSD license. It was described by IEEE as IEEE 1275-1994 but since 1998, it has been withdrawn. In 2006 several commercial versions were released to the open source community under the OpenBIOS project, these include, SUN OpenBOOT, Firmworks OpenFirmware and Codegen SmartFirmware. Open Firmware is a hardware independent firmware and fulfils the same tasks as BIOS does in a PC. The advantage of Open Firmware to Apple is that any I/O cards that work, in say SUN machines, could also be used in Mac machines without requiring any specific Mac drivers. Open Firmware also offered BOOTP capabilities for Netbooting machines as well as setting boot devices. On a Macintosh, most user settings can be changed via GUI tools and the Open Firmware can be locked to prevent booting from non-authorized sources.

Extensible Firmware Interface (EFI)

History

EFI was developed by Andrew Fish working for Intel back in the 1990's and was initially called "Intel Boot Initiative (IBI)". It grew up around the need to replace the aging PC BIOS developed by IBM in the 1970's. IBI was intended for their Itanium Architecture (IA) based computers because the existing PC BIOS was far too limiting for future 64 bit operating systems, some of these problems being 16 bit processor mode and PC AT hardware dependencies to name a few. Since then, IBI was developed by Intel into EFI and subsequently released by them to the open source community in 2005. It is now called UEFI (Unified Extensible Firmware Interface) and is currently at version 2.1.

Due to the failed performance of these IA machines, EFI never took off as a common replacement for the PC BIOS. In 2006, Apple moved to EFI and was then the only vendor to take advantage of this firmware interface. Linux has supported EFI since 2000 using "elilo" as a boot loader and both Windows and HP-UX support EFI, but all of these only support IA-32 and IA-64 platforms. Windows Vista is expected to support EFI but only in a later service pack and Microsoft's stance is that until EFI becomes mainstream they will not support it.

What is EFI?

EFI was designed to abstract the firmware and hardware layers from the operating system layer. This is so that operating system vendors and developers no longer need to battle with cumbersome 16bit BIOS and constant hardware configurations.


Fig 1. Legacy PC BIOS vs. EFI

Figure 1 compares EFI and BIOS showing EFI as a standard interface between the OS and the hardware. EFI is a set of specifications to define interactions and programmatic interfaces between the hardware and the operating systems, it is then up to the specific hardware vendors to make an EFI compliant system. Since EFI is just a set of specifications, it is not an actual firmware; therefore, it is up to each vendor to create their own firmware to initialize their hardware. Intel's firmware, and hence Apple's choice, is called "Intel Platform Innovation Framework for EFI", also called "Framework". It is a legacy free firmware that complies with EFI. It is not available to end-users as a complete firmware package but parts of the code are released under the TianoCore project, (www.tianocore.org). Apple created their own version of "Framework"; we will see later how they implemented EFI and framework.

EFI is very similar to Open Firmware in that it is a boot firmware independent of hardware and operating system. What this means is that it allows the operating system to boot and run in a "sandbox" mode. A "sandbox" mode is a safe protected mode where the operating system does not make direct calls to the hardware. EFI controls the hardware; it takes the calls from the operating system, and then passes them on to the hardware, creating an interface between the OS and the physical firmware, in much the same way that a virtual machine works. This then offers a stable environment from which to run the OS. The advantage of this is that only the firmware controls the hardware (see Fig 2).


Figure 2 - EFI as an interface between the OS and the Firmware

For developers this means they will no longer need to make BIOS/OS dependant drivers, they can create EFI based drivers which will then work in any compatible EFI machine irrelevant of the OS or BIOS loaded. Obviously, for Apple this means a wider range of I/O cards can be supported in the future once more hardware vendors support EFI. EFI is free of any of the memory restrictions that BIOS has and can use all available memory. This speeds up boot time as well, a Mac Pro for instance can boot up and load the OS in just 15 seconds.

The EFI specification is broken down into "boot services" and "runtime services". Boot Services are any services that run during boot only, such as, the loading of drivers and the accessing of graphics during boot. The services use "EFI Drivers" "EFI Applications" and "EFI Boot Code". Runtime Services run while the computer is running accessing such things as date/time etc. EFI Drivers are written in C and conform to the EFI Drivers Model. They can be loaded from any non-volatile memory, either in option ROM, or on the device directly.

Apple's implementation of EFI and Framework

The EFI Boot Process

Firstly, the computer powers up, then Framework, then, via EFI boot services, initializes the hardware such as the Bluetooth, USB, VGA, network IP stack, remote control, etc. These boot services will load all the hardware drivers necessary to detect any OS that resides on either an internal or external hard disk, or a network volume. Apple's Framework does not boot into text mode but directly into graphics mode, just like it did with Open Firmware. There is no direct access to the text mode or EFI shell. Apple has developed their Framework to work in much the same way as Open Firmware did, using the same key strokes: C boots to CD/DVD, N boots into the Netboot disk, V boots verbose and S boots into Safe Mode, etc. This makes a seamless transition from Open Firmware to EFI for the user.

Following this, various EFI Applications can be loaded; one such application is the Boot Manager. The Boot Manager is used to select and load the operating system, removing the need for a dedicated boot-loader mechanism. On an Apple this looks very similar to the Open Firmware boot-loader but with updated graphics. Apple has created their own EFI compliant Boot Manager with their own graphics. Apple's Boot Manager can detect any Mac operating system that is available to the system. According to Apple, their EFI Application can, however, only read boot-code from a GPT formatted drive or an Intel based NetBoot image; only one Netboot image is displayed and is either set via the "Startup Disk" section on the client or is the default image set on the server. Initially the Boot Manager could only detect Mac OS, but Apple used the "compatibility support module" to support legacy PC BIOS such as XP. This will only display a single legacy OS per drive.


Figure 3 - EFI with the CSM Module

Apple's Boot Manager Application will either boot from the default volume or you can enter the graphical selection screen via the option keystroke, just as with Open Firmware. The EFI boot code is then read from the hard disk and the operating system is loaded. Control is then transferred to the OS. Some higher operating system drivers can now be loaded for various devices. The operating system will then pass calls to the firmware, which will pass them to the hardware.


Figure 4 - EFI Boot Process

rEFIt tools

When Apple released BootCamp with their Firmware update, which added the compatibility support module to their firmware, it became possible to load the Linux OS onto a Mac. However, this module only recognizes a single legacy OS per drive and labels them as Windows only. This is not useful in a triple boot system. An open source project was then started called rEFIt tools which offers a boot menu to detect multiple OS per drive and label them as the appropriate OS's. It also offers a maintenance toolkit with direct access to the EFI pre-boot environment and gives access to the EFI Shell Application. The current version is 0.8 and can be loaded via CD, USB or directly off the internal drive. When you boot the Mac with the option key held down, you can then select the rEFIt tools from their installed location.

Conclusion -- Future Benefits of EFI for Apple

EFI is a complete pre-boot environment, that makes life much easier for developers, and since EFI is written in C, it is much easier to program for. With more vendors supporting this specification it means, for Apple users, that more and more devices with be compatible with Macs. This can only be a good thing. Developers find it a much easier environment to develop in due to its pre-boot environment. They can test and develop without the need for a VDU because they can output the tests directly to text. The pre-boot environment can also be used for backup, recovery, and diagnostics, updating firmware by accessing the Internet without the need for an OS. Both American Megatrends Inc (AMI) and Insyde Technology, both members of UEFI, have made Pre-Boot Applications sets.


Figure 5 - AMI Pre-Boot Interface

There are development tools available that allow users to create their own pre-boot applications.


Figure 6 - Pre-Boot Applications

This offers Apple the chance to create their own Pre-Boot Applications which can be stored on the System EFI partition, which is currently empty on Apples GPT drives, but is created by default with a set size of 200mb. Apple could develop pre-boot versions of Time Machine for Leopard so that an OS X system could be recovered via an existing backup, or use a pre-boot Disk Utility to repair a drive. Third party companies such as Norton or Tech Tool could install pre-boot versions of their Applications to this hidden partition also. Apple could also make a pre-boot version of Front Row so that users can access their DVD's, MP3s, AppleTV without needing to boot the OS. This also offers secure network booting, remote provisioning and setup as well as virus scanning etc. For the general user it will offer them a stable environment to run the Mac OS X without as many kernel panics.

Bibliography and References

UEFI. UEFI Extensible Firmware Interface Specifications Version 2.1, Copyright 2006.

Windows Hardware Developer Central, EFI and Windows, April 2006.

Wikipedia, Extensible Firmware Interface, 2007.

Wikipedia, Open Firmware, 2007.

Wikipedia, BIOS, 2007.

OSX86Project, EFI, February 2007.

Intel Software Network, Extensible Firmware Interface, 2006.

Intel Software Network, Enhanced Pre-Boot Environments with EFI Applications, 2007

Michael Kinney - Intel Developer Update Magazine, Solving Boot Issues with EFI, September 2000

Amit Singh - Kernelthread.com, More Power to Firmware, Copyright 2006.

American Megatrends Inc, AMI Pre-Boot Applications, December 2005.


Criss Myers is a Senior Mac IT Technician for the Faculty of Science and Technology, at the University of Central Lancashire, Preston, United Kingdom. He has been a Systems Server Administrator from the very first version of OS X Server. He Works with Macs as well as Linux, Unix and Windows.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

MarsEdit 4.3 - Quick and convenient blog...
MarsEdit is a blog editor for OS X that makes editing your blog like writing email, with spell-checking, drafts, multiple windows, and even AppleScript support. It works with with most blog services... Read more
TeamViewer 14.2.2558 - Establish remote...
TeamViewer gives you remote control of any computer or Mac over the Internet within seconds or can be used for online meetings. Find out why more than 200 million users trust TeamViewer! Free for non... Read more
Chromium 73.0.3683.75 - Fast and stable...
Chromium is an open-source browser project that aims to build a safer, faster, and more stable way for all Internet users to experience the web. Version 73.0.3683.75: This update includes 60... Read more
Sublime Text 3200 - Sophisticated text e...
Sublime Text is a sophisticated text editor for code, markup, and prose. You'll love the slick user interface, extraordinary features, and amazing performance. Features Goto Anything. Use Goto... Read more
PopChar Family Pack (5 licenses) 8.6 - F...
PopChar helps you get the most out of your font collection. With its crystal-clear interface, PopChar provides a frustration-free way to access any font's special characters. Features Expanded... Read more
PopChar 8.6 - Floating window shows avai...
PopChar helps you get the most out of your font collection. With its crystal-clear interface, PopChar provides a frustration-free way to access any font's special characters. Features Expanded... Read more
Tor Browser Bundle 8.0.7 - Anonymize Web...
The Tor Browser Bundle is an easy-to-use portable package of Tor, Vidalia, Torbutton, and a Firefox fork preconfigured to work together out of the box. It contains a modified copy of Firefox that... Read more
MegaSeg 6.0.8 - Professional DJ and radi...
MegaSeg is a complete solution for pro audio/video DJ mixing, radio automation, and music scheduling with rock-solid performance and an easy-to-use design. Mix with visual waveforms and Magic... Read more
FileZilla 3.41.2 - Fast and reliable FTP...
FileZilla (ported from Windows) is a fast and reliable FTP client and server with lots of useful features and an intuitive interface. Version 3.41.2: Fixed vulnerabilities: Backport a security... Read more
Spotify 1.1.2.285. - Stream music, creat...
Spotify is a streaming music service that gives you on-demand access to millions of songs. Whether you like driving rock, silky R&B, or grandiose classical music, Spotify's massive catalogue puts... Read more

Latest Forum Discussions

See All

The best shooters on iOS
In case you missed it yesterday, Tencent and Activision announced they are putting out a new Call of Duty game for mobile. While details are pretty scant, they did put out a trailer (see above) and have a page where you can pre-register for the... | Read more »
The best games for iPhone - The definiti...
Hi there, and welcome to our ever-increasing list of the very best games for iPhone. We're going to be updating this regularly with new content, so make sure you check back often, because you're not going to want to miss out on even one of the... | Read more »
Everything you need to know to win in Sp...
Sure, Sprout: Idle Garden might be an idle game (we know, we know, it was pretty obvious from the name), but that doesn't mean there aren't plenty of hints and tips you can exploit to make sure you're getting the best possible return from your... | Read more »
Huge new update for fantasy RPG Final Bl...
The hit fantasy RPG Final Blade arrived on western shores last month to much acclaim, thanks in large part to its successful mix of vibrant visuals, rich storytelling, and classic RPG mechanics. Now, the game is set to receive a whopping new update... | Read more »
Everything you need to know to win in Pe...
Pet Rescue Puzzle Saga is the latest game in King's long line of sagas. It's a match-stuff puzzler, as you might expect, but it's got a few new twists on the already established formula that, while they do keep things fresh, are likely to come as... | Read more »
REKT! guide - Is the latest content upda...
When REKT! first came out, I was impressed with the game’s ability to channel the gameplay of Tony Hawk’s Pro Skater in a small, streamlined package. Be that as it may, I was also pretty underwhelmed with the game’s lack of content. | Read more »
The best games for iPhone and iPad that...
Just like every Thursday, today we're taking some time to let you know what we think are the best games that have come out over the past week. We've had hands-on time with all of them, so you can trust us when we tell you that we're pretty clued... | Read more »
Mobile games you probably haven't p...
The App Store is bursting at the seams with all kinds of apps and games of varying quality, but one of the most consistent issues with it is discoverability. Despite having what seems like unlimited money and a full App Store editorial team, Apple... | Read more »
Get gorgeous characters and new skins in...
NetEase Games’s Onmyoji is reaching the last part of the crossover event with the classic anime Inuyasha. Once the maintenance on March13th is over you’ll be able to get Inuyasha, Sesshomaru, and Kikyo. You can get hold of these through any summon... | Read more »
Everything you need to win in Scorcher f...
There's no denying that Scorcher from Radiangames is a difficult game. It's the sort of game where, when you first start playing, you're going to die over and over and over again. There's a chance that those repetitive deaths are going to put you... | Read more »

Price Scanner via MacPrices.net

Apple drops prices on clearance refurbished 4...
Apple has dropped prices on Certified Refurbished 2017 21″ 4K & 27″ 5K iMacs with models now available starting at $1059. Apple’s one-year warranty is standard, shipping is free, and each iMac... Read more
Blowout sale! New 2018 15″ 6-Core Apple MacBo...
Amazon has dropped prices on new 2018 15″ 6-Core Touch Bar MacBook Pros with models now on sale for $500 off Apple’s MSRP, starting at $1899. These are the same models sold by Apple in their retail... Read more
New Verizon deal: Buy one iPhone Xs, Xs Max,...
Verizon is offering a free 64GB iPhone Xr, or $750 back on any other iPhone model, for those who are purchasing a new iPhone Xr, iPhone Xs, iPhone Xs Max, or iPhone X on their online store. Here are... Read more
Deal Alert! Amazon has the high-end 2018 15″...
Amazon, for a limited time, is selling the high-end 2018 15″ 2.6GHz Silver MacBook Pro (16GB RAM/512GB SSD/Touch Bar) for only $2299.99 including free shipping. That’s $500 off Apple’s price, and it’... Read more
Amazon is offering base 13″ 2.3GHz Dual-Core...
Amazon has new 13″ 2.3GHz Dual-Core non-Touch Bar MacBook Pros on sale for $250-$300 off Apple’s MSRP, with prices starting at only $1049. Their prices are the cheapest available for new 13″ MacBook... Read more
Apple drops prices on clearance refurbished 1...
Apple has dropped prices on Certified Refurbished 2016 9.7″ iPad Pros and 2017 10.5″ iPad Pros, with models now available starting at $419. An Apple one-year warranty is included with each iPad,... Read more
Apple announces new 2019 10.5″ iPad Air and 7...
Apple today announced an all-new 10.5″ iPad Air and 7.9-inch iPad mini. With the A12 Bionic chip with Apple’s Neural Engine, the iPad Air delivers a claimed 70% boost in performance and twice the... Read more
Sunday Sale! 13″ 2.3GHz/256GB Dual-Core Silve...
Amazon has the 13″ 2.3GHz/256GB Silver MacBook Pro on sale today for $1199.99 shipped. That’s $300 off Apple’s MSRP and the cheapest price for this model from any Apple reseller. This is the same... Read more
Find the best sales & lowest prices on Ap...
Our Apple award-winning price trackers are the best place to look for the best sales and lowest prices on Apple gear. Scan our price trackers for the latest information on sales, bundles, and... Read more
Breathe New Life Into Your Older iPhone With...
FEATURE: 03.17.19- iPhone owners wanting to replace the battery on their smartphone who missed last year’s special discounted $29 battery replacement program from Apple — which was the Cupertino,... Read more

Jobs Board

*Apple* Practice Director - CompuCom (United...
…Join the team today by applying to the following role: Position Summary:The Apple Practice Director is dedicated to the Apple business and willcollaborate Read more
Geek Squad *Apple* Master Consultation Agen...
**680044BR** **Job Title:** Geek Squad Apple Master Consultation Agent **Job Category:** Services/Installation/Repair **Location Number:** 000308-Orland Park-Store Read more
Best Buy *Apple* Computing Master - Best Bu...
**677136BR** **Job Title:** Best Buy Apple Computing Master **Job Category:** Sales **Location Number:** 000417-Novi-Store **Job Description:** **What does a Best Read more
Best Buy *Apple* Computing Master - Best Bu...
**670898BR** **Job Title:** Best Buy Apple Computing Master **Job Category:** Store Associates **Location Number:** 001102-Jefferson City-Store **Job Description:** Read more
*Apple* Technician - Sentinel (United States...
…Motivated you can join our team and make IT happen! Learn more at www.sentinel.com/careers. Apple Technician As an Apple Technician, you will test and deploy new Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.