UEFI Boot FAQ

Frequently Asked Questions:

Q: What is UEFI?

A: UEFI is a modernized startup firmware designed to replace the classic BIOS.The old BIOS system has some severe limitations in both software and hardware, UEFI is designed to be extensible and more powerfull.

Microsofts short explanation-> http://windows.microsoft.com/en-us/windows-8/what-uefi

Technical info from Wikipedia-> http://en.wikipedia.org/wiki/Unified_Extensible_Firmware_Interface

Q: Why do i need BIOS or UEFI:

A: Before your computer or tablet can connect to its built in storage device and boot an operating system, it needs to initialize its internal devices and make the system ready for boot. This is done with internal firmware like the Legacy BIOS or the more modern UEFI.

Q: Why do i need to build UEFI specific images?

A: New 64 and 32 bit hardware support demands new initial boot images must be created.

Q: How can i tell if my device is UEFI based?

A: Most newer computers and devices supports UEFI booting. Check the official specifications of your device to see what level of UEFI booting your device supports.

Q: How do i enable UEFI booting from the network on my machine. Unfortunately vendors have very different ways of presenting the UEFI options in their firmwares. You should refer to the official documentation and take note of the machines firmware version to be sure to find the setting for enabling UEFI booting on the network.

Q: I have enabled UEFI as a boot method, but i cannot boot on the network?

A: Check if the UEFI setting explicitly mentions network booting. Some early machines have UEFI booting implemented on the internal disks or USB bot not on the Network Interface Card.

Q: My device supports network booting over UEFI, but it still won't boot?

A: Make sure that "Secure Boot" is disabled on your device, with Secure Boot on UEFI network booting will not work.

Q: What ethernet devices are supported for PXE/UEFI boot

A: Support for USB network devices is not class driver based- individual chips have notable functional differences, and as such there is no class driver for USB networking- thus, support is left to motherboard OEM’s to build support for individual networking devices into their devices- a challenging task.

For this to be possible, the BIOS/UEFI on the motherboard has to natively support the chip used in the USB network adapter- so this answer will always depend on the motherboard, and require research into both the chipset of the USB network device and then whether the UEFI/BIOS a given motherboard runs supports this chip.

The vast majority of “legacy” systems will NOT have the ability to PXE boot a USB attached adapter. On more modern systems, this functionality will vary from model to model and is NOT something we can answer with certainty, as it is effectively a question of whether the motherboard’s software has support for the chip used in the adapter.

This is much less likely to work on newer USB 3.0 networking devices than on USB 2.0 devices, since those are based on chips that have been around longer, thus giving motherboard OEMs and the open source community time to integrate support for these USB devices into BIOS/UEFI and the alternate pre-installation environments.

Q: Why do tranfering the boot.vim fail or run very slowly

A: Depending on your network card and size of the boot image the time it takes to download the boot image may vary.

For more technical info read on -> http://technet.microsoft.com/fr-fr/library/cc772277(v=ws.10).aspx

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