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 It was described by IEEE as IEEE 1275-1994 but since 1998, it has been withdrawn.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.

 
AAPL
$101.79
Apple Inc.
+0.21
MSFT
$46.68
Microsoft Corpora
+0.16
GOOG
$589.27
Google Inc.
+4.50

MacTech Search:
Community Search:

Software Updates via MacUpdate

Duplicate Annihilator 5.0 - Find and del...
Duplicate Annihilator takes on the time-consuming task of comparing the images in your iPhoto library using effective algorithms to make sure that no duplicate escapes. Duplicate Annihilator detects... Read more
jAlbum Pro 12.2 - Organize your digital...
jAlbum Pro has all the features you love in jAlbum, but comes with a commercial license. With jAlbum, you can create gorgeous custom photo galleries for the Web without writing a line of code!... Read more
jAlbum 12.2 - Create custom photo galler...
With jAlbum, you can create gorgeous custom photo galleries for the Web without writing a line of code! Beginner-friendly, with pro results Simply drag and drop photos into groups, choose a design... Read more
Quicken 2015 2.0.4 - Complete personal f...
Quicken 2015 helps you manage all your personal finances in one place, so you can see where you're spending and where you can save. Quicken automatically categorizes your financial transactions,... Read more
iMazing 1.0 - Complete iOS device manage...
iMazing (formerly DiskAid) is the ultimate iOS device manager with capabilities far beyond what iTunes offers. With iMazing and your iOS device (iPhone, iPad, or iPod), you can: Copy music to and... Read more
Xcode 6.0.1 - Integrated development env...
Apple Xcode is Apple Computer's integrated development environment (IDE) for OS X. The full Xcode package is free to ADC members and includes all the tools you need to create, debug, and optimize... Read more
Apple Safari 7.1 - Apple's Web brow...
Apple Safari in OS X Mavericks brings you all-new ways to find and enjoy the best of the web. It works with iCloud to give you a seamless browsing experience across all your devices. It looks out for... Read more
Delivery Status 6.1.2 - Check delivery s...
Delivery Status displays delivery status of packages for a variety of shipment services. Can't wait for your packages to arrive? Don't waste your time checking the site constantly, just open this all... Read more
Mavericks Cache Cleaner 8.0.9 - Clear ca...
Mavericks Cache Cleaner is an award-winning general purpose tool for OS X. MCC makes system maintenance simple with an easy point-and-click interface to many OS X functions. Novice and expert users... Read more
OneNote 15.2.2 - Free digital notebook f...
OneNote is your very own digital notebook. With OneNote, you can capture that flash of genius, that moment of inspiration, or that list of errands that's too important to forget. Whether you're at... Read more

Latest Forum Discussions

See All

Project Life (Photography)
Project Life 1.0 Device: iOS Universal Category: Photography Price: $2.99, Version: 1.0 (iTunes) Description: Imagine scrapbooking without scissors or adhesive or tools … or without having to print photos! Never before has... | Read more »
Skater (Games)
Skater 1.0 Device: iOS iPhone Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: All of Skateboarding In The Palm Of Your Hand Designed by skaters for skaters, we teamed up with 17 of the most prominent brands in... | Read more »
Huerons (Games)
Huerons 1.1 Device: iOS Universal Category: Games Price: $.99, Version: 1.1 (iTunes) Description: EXCLUSIVE LAUNCH PRICE! Huerons is 50% off until September 20th! Huerons are tiny colored circles. Merge them by clicking on an empty... | Read more »
Down Among the Dead Men (Games)
Down Among the Dead Men 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: Avast! Take to the high seas in a fully interactive piratical tale of broadsides and buccaneers. From author Dave... | Read more »
Sling Adds Chromecast Support Through Sl...
Sling Adds Chromecast Support Through Slingplaye​r Mobile Apps Posted by Jessica Fisher on September 18th, 2014 [ permalink ] | Read more »
How to Completely Delete Your iPhone’s C...
The iPhone 6 is out tomorrow, and plenty of people are excited about it. So much so that they’re planning to – or already have – traded in their old iPhone to go towards it. The thing about trading in hardware is it’s very important to make sure... | Read more »
Dragon Quest I Review
Dragon Quest I Review By Andrew Fisher on September 18th, 2014 Our Rating: :: THINE QUEST AWAITETHUniversal App - Designed for iPhone and iPad Its historical significance aside, Dragon Quest 1 is a fun, campy, difficult, thoroughly... | Read more »
It Came From Canada: Overkill 3
Overkill 3 is like every trope of big modern gaming rolled into one. It’s a sequel to an action-packed military shooter. It’s flashy and scripted and flaunts its sophisticated graphics. And it’s a mobile game with a heavy emphasis on in-app... | Read more »
New Modes and Leader Boards in Update fo...
New Modes and Leader Boards in Update for Rules! Posted by Jessica Fisher on September 18th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
TwistedRun Review
TwistedRun Review By Rob Thomas on September 18th, 2014 Our Rating: :: DON'T TWIST YOUR ANKLE!Universal App - Designed for iPhone and iPad TwistedRun is kind of like running up a giant curly fry into the sky. Or maybe that was just... | Read more »

Price Scanner via MacPrices.net

iOS 8 Adoption Rate Slower than iOS 7, 6, Hit...
Apple began pushing out iOS 8 updates to eligible devices around 1pm ET on September 17, 2014. However, unlike with iOS 7, which boasted a wide variety of differences from its predecessor iOS 6, in... Read more
Save up to $300 on the price of a new Mac wit...
Purchase a new Mac or iPad at The Apple Store for Education and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free,... Read more
13-inch 2.8GHz Retina MacBook Pro available f...
B&H Photo has the new 2014 13″ 2.8GHz Retina MacBook Pro on sale for $1699.99 including free shipping plus NY sales tax only. They’ll also include free copies of Parallels Desktop and LoJack for... Read more
16GB iPad Air on sale for $449, save $50
Walmart has the 16GB iPad Air WiFi on sale for $449 on their online store for a limited time. Choose free home shipping or free local store pickup. Their price represents a $50 savings over standard... Read more
13-inch 256GB MacBook Air on sale for $1099,...
B&H Photo has the 2014 13″ 1.4GHz 256GB MacBook Air on sale for $1099.99. Shipping is free, and B&H charges NY sales tax only. Their price is $100 off MSRP. Read more
Toshiba Introduces TransMemory ID High-Speed...
Toshiba’s Digital Products Division (DPD), a division of Toshiba America Information Systems, Inc., today introduced the TransMemory ID USB 3.0 Flash Drive, a simpler storage solution for people who... Read more
New iPads and OS X Yosemite Release Coming Oc...
The DailyDot’s Micah Singleton reports that Apple is planning to hold its next product announcement event on Oct. 21, at which it will unveil the iPad Air 2 and iPad mini 3 and release a final build... Read more
Logitech Bluetooth Multi-Device Cross-Platfor...
Logitech has an enviable track record of making some of the best computer keyboards and mice. At least in my estimation, the best freestanding keyboards I’ve ever used have been Logitech units,... Read more
Roundup of Apple refurbished iPad Airs and iP...
Apple is offering Certified Refurbished iPad Airs for up to $140 off MSRP. Apple’s one-year warranty is included with each model, and shipping is free. Stock tends to come and go with some of these... Read more
Sprint offers 16GB iPad mini for $199.99 with...
Sprint is offering 1st generation 16GB iPad minis for $199.99 with a 2-year service agreement. Standard MSRP for this iPad is $429. Their price is the lowest available for this model. Read more

Jobs Board

Project Manager, *Apple* Financial Services...
**Job Summary** Apple Financial Services (AFS) offers consumers, businesses and educational institutions ways to finance Apple purchases. We work with national and Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.