Right, hmm, I haven't looked into how EFI booting works, but if it is similar enough to regular booting, then, after NTLDR (or its EFI equivalent) is loaded, then you just have to chainload another OS from the boot selection menu. Let me go see if this is plausible; then I'll post back.
EDIT:
EFI / UEFI seems to be a really good concept, and have been around for a long time, even without user knowledge, as some UEFI manufacturers have BIOS emulators built in. The idea behind UEFI is that the BIOS can perform diagnostic and other functions on its own, as well as UI (GUI or otherwise), and can load an OS, and provide low-level drivers for the OS to use until the OS's own specialized drivers take over (e.g., graphics while booting until the regular drivers can take over. Normally, the OS loads the basic graphics driver first, and then the specialized one later). UEFI (in its previous EFI form) has been supported since early 2000 era with no big fuss. However, your concern stems from M$ trying this nice little power grab: (-gasp! who would've thought??)
http://en.wikipedia.org/wiki/Unified_Extensible_Firmware_InterfaceMicrosoft will demand that computers with the "Designed for Windows 8" logo use UEFI with secure boot (which will only allow signed software to run on the device) enabled by default.[39][40] Red Hat developer Matthew Garrett raised concerns over the requirement for secure booting to be enabled by default and Microsoft responded by saying that there was no mandate from Microsoft that prevents secure booting from being disabled in firmware or that keys could not be updated and managed.[39][40] Microsoft later reversed this position, mandating that disabling SecureBoot on ARM-based systems "MUST NOT be possible."[41]
EDIT2: Hmm, there was more further down... IDK why the criticism is about UEFI, though, the problem seems to just be M$'s demands about Winblows 8....
Numerous digital rights activitists have protested against UEFI. Ronald G. Minnich, a co-author of coreboot, and Cory Doctorow, a digital rights activist, have criticized EFI as an attempt to remove the ability of the user to truly control his computer.[46][47] It does not solve any of the BIOS's long standing problems of requiring two different drivers—one for the firmware and one for the operating system—for most hardware.[48]
TianoCore,[49] an open-source project which provides the UEFI interfaces, lacks the specialized drivers that initialize chipset functions, which are instead provided by coreboot, of which TianoCore is one of many payload options. The development of Coreboot requires chipset manufactures to cooperate by providing specifications needed to develop initialization drivers.
UEFI reimplements a full networking stack, unlike many BIOSes, and therefore is a target for remote security exploits.[50]
Secure Boot
See also: Windows 8#Secure boot and Hardware restrictions#Windows 8
In his article "UEFI secure booting", Red Hat developer Matthew Garrett raised a concern that UEFI's "secure boot" feature may impact Linux: Any machine with the Windows 8 logo and with secure boot enabled and that ships with only OEM and Microsoft keys will not boot a generic copy of Linux.[51][52] In response, Microsoft stated that customers may be able to disable the secure boot feature in the UEFI interface.[2][53] Concern remained that some OEMs might omit that capability in their computers, and later it was reported that Microsoft apparently prohibited the implementation of such a feature on ARM systems.[54][55]
Joshua Gay of the Free Software Foundation (FSF) also raised concerns about "secure boot"; the FSF declared a public statement open for anyone to sign:
We, the undersigned, urge all computer makers implementing UEFI's so-called "Secure Boot" to do it in a way that allows free software operating systems to be installed. To respect user freedom and truly protect user security, manufacturers must either allow computer owners to disable the boot restrictions, or provide a sure-fire way for them to install and run a free software operating system of their choice. We commit that we will neither purchase nor recommend computers that strip users of this critical freedom, and we will actively urge people in our communities to avoid such jailed systems.[56][57]
In December 2011, Microsoft released a document about hardware certification of OEM products: Windows Hardware Certification Requirements, [41] confirming significantly different requirements regarding secure boot for the x86/x86-64 architecture and the ARM architecture. It has been revised several times since being issued. As of July 30 2012, the document requires that x86 and x86-64 devices have "secure boot" enabled by default. However, it requires that the firmware include an option to disable secure boot, and also a custom secure boot mode that provides the ability to add cryptographic signatures from vendors other than Microsoft. ARM devices are required to have secure boot enabled by default, and are required not to provide either an option to disable it, nor a custom mode that allows the user to add alternate signatures.[54]
EDIT3: So, I guess the TL;DR version is M$ is trying to say "**** off, we
own ARM" ?? And possibly x86 and x86-64 if they can get that too...
EDIT4: Easiest way around this: create some "company" that sells a universal UEFI chainloader for other OSes (there is one mentioned somewhere in the wiki article I think, openboot or somesuch)
anyways, have the OEMs sign their UEFI for
that, then use the software bootloader to have the signature keys from M$ to load their bloatware if desired, along with nice OSes likee Linux and MacOS.
