UEFI boot and startup problems
Windows 8's tight integration with a PC's UEFI can be especially problematic when you need to run bootable rescue media.
UEFI components that might cause boot troubleThere are five elements of UEFI that can defeat your attempts to launch self-booting media. Later in the story, you'll see how to adjust these items. But first, the following general descriptions will help you understand what the five elements do.
Note: Though Windows 8 can implement all five elements, Vista and Windows 7 systems use subsets of these components. It's also important to know that each hardware vendor might enable or disable a different set of UEFI features — or call them by different names. I've used the most common names below.
Also, when discussing a "Win8 system," I mean a PC that was designed to run Windows 8. The OS will run on older PCs, but an older UEFI probably won't have all five components Win8 supports. The same holds for Vista and Win7 machines.
§ UEFI/CSM Boot: Virtually all Win8 — and many Vista and Win7PCs — can boot with either the generic UEFI system (UEFI Boot) or a compatibility-support module (CSM Boot). CSM Boot emulates old-style BIOS actions for operating systems that require it. In some cases, CSM Boot must be specifically enabled before a PC will boot from a "foreign" operating system or from a device other than the hard drive. What's more, to use CSM Boot, both UEFI Boot and Secure Boot (see next item) must be disabled.
§ Secure Boot is a Win8-specific, UEFI implementation that prevents unauthorized or unrecognized operating systems from loading. For example, some classic Linux-based repair/recovery discs lack the required security certifications; they won't boot if a PC is in Secure Boot mode. If you disable Secure Boot, the system reverts to the generic UEFI Boot.
§ Fast Boot is a UEFI option that often varies by vendor and Windows version. In older systems with simpler UEFI implementations, Fast Boot saves a few seconds at startup by skipping several routine hardware checks.
With Windows 8, Fast Boot significantly speeds the startup process by overriding and skipping many optional settings. For example, it always boots directly from the primary hard drive — no matter what other boot-order settings you might have set manually.
Typically, Win8's Fast Boot must be disabled if you want to boot from a standard optical drive, flash drive, network drive, etc. — essentially any source other than your primary hard drive.
§ Trusted Boot is a UEFI module that checks the integrity of the startup software before allowing it to load. Trusted Boot is disabled when you select CSM boot.
§ Early Launch Anti-Malware (ELAM) is a Win8-specific UEFI implementation that's active when Secure Boot is enabled. Launching early in the initial boot process, ELAM scans all subsequently loaded system-level drivers to ensure they're not carrying hostile payloads such as rootkits.UEFI/CSM Boot, Secure Boot, and Fast Boot usually can be managed separately by end users; Trusted Boot and ELAM typically cannot.
A fully accurate test for UEFI boot problemsYou obviously don't want to discover UEFI-related boot problems while attempting to recover from a major system failure. It's far better to test your UEFI settings now — well before an emergency.
The test is safe and simple, and it takes only minutes. You simply create a bootable CD, DVD, or flash drive and then try to boot your system from it.
Though any type of bootable media will do, it's best to test the UEFI with the combination of media and recovery tool you'll use if your PC encounters trouble.
Steps for testing Window 8's UEFI configurationPreparation and first steps: As with any major change to your PC, start by saving all your work, closing all running apps, and backing up the system.
§ Simplify your PC's boot hardware as much as possible. Disconnect all potentially bootable external devices — except the one from which you intend to actually boot. For example, if you're going to boot from a DVD, unplug any unneeded USB drives or flash devices currently connected to your system.
§ Open the Charms bar, click the gear icon (Settings), and then click Change PC settings at the bottom of the bar.
§ On the PC settings page, select Update and recovery.
§ Click Recovery and then, under Advanced startup, click Restart now. (Despite the terminology, your PC will not immediately restart — that's normal.) The Choose an option page will open.If your PC has UEFI-compatible hardware, you'll see a Use a device option (see Figure 1).
The simple "Use a device" option: If it's available to you, Win8's Use a device options menu is the easiest way to try booting from alternate media or the network. It automatically makes temporary adjustments to the relevant UEFI settings (including Fast Boot and Boot Order) to allow booting from the device you select.
(Use a device won't work if the hardware is incompatible with UEFI or the alternate OS is incompatible with Secure Boot.)
Unfortunately, there's no way to know in advance whether all aspects of your system will work correctly with the Use a device setting — you simply have to try booting your PC with the selected device and see what happens. Here's how:
§ Click on Use a device.
§ Click on the EFI (extensible firmware interface) device that you want to boot from: USB, DVD/CDROM, or network.
§ Click the Reboot button when it's offered; your PC will shut down and then try to boot from whatever device you selected.
§ Follow the instructions for whatever prompt then appears. For example, if you're booting from an optical drive, you should press a key when the Press any key to boot from DVD or CD ROM prompt appears.Note: If you have trouble booting from a USB-based drive, use a USB 2.0 port (typically denoted by a white or gray connector) if possible. I've found USB 2.0 to be more reliable than USB 3.0 (blue connector) in boot operations.
If your system boots from your recovery media, you're done! Your hardware, media, and software are all UEFI-boot compatible — as they are.
If the boot process fails, you'll likely get a rather generic error message. For example, if I try to boot my system from a DVD containing a Linux distribution that's not compatible with Secure Boot, I get the error message: "System doesn't have any CD/DVD boot option." It does have that option, of course — the drive was selected in Use a device — but that option is incompatible with Secure Boot.
No matter what error message you receive, if your PC fails to boot via the Use a device option, just bail; reboot normally back to Windows, work your way back to the Choose an option screen, and follow the steps below.
The Advanced alternate booting option: If Use a device isn't available or fails, your next stop is the Advanced alternate booting option, available under the Troubleshooting menu.
On the Choose an option screen, click Troubleshoot and then Advanced options (Figures 3 and 4).
If no such option exists, skip down to the section below labeled "If there's trouble — or no UEFI menu at all."
Working inside the UEFI management softwareUEFI setting pages often look much like classic BIOS screens — and typically work in much the same way. Follow the on-screen directions for navigating to the settings you're going to change. Next, make the following changes.
On Windows 8 systems, start by disabling Secure Boot. The setting is typically found under Security (see Figure 7), Boot, Authentication, or some similar heading.
On my system, this requires three clicks: one to access the Advanced/System Configuration menu (Figure 9), a second to access the Boot Mode settings, and a third to change to CSM Boot (Figure 10).
Now set the boot order; you want your PC to first try the device you selected, upon restart. UEFI boot-order settings are usually under the Boot section (or something similar).
For example, if you want to boot from a DVD/CD drive, change the PC's boot order so that the optical drive is at the top of the list. Your options will likely look somewhat similar to those shown in Figure 11.
Your system will now restart, using a traditional BIOS-type (CSM) boot process. It'll bypass Secure Boot, skip the Fast Boot shortcuts, and attempt to use whatever device you selected as the first boot device.
If there's trouble — or no UEFI menu at allIf you know your system has a UEFI, but you can't find or access its settings, almost all systems offer the alternate, old-school trick of pressing a specific function key during initial boot or using special OEM software. However, whenever possible, it's best — and safest — to use the menu-access methods described above. It will ensure that Windows and the UEFI system remain in sync.
If you've tried everything in this article and still can't properly control UEFI booting, visit your PC vendor's online support site and search for instructions specific to your brand and model of PC.
Wrapping up, plus sources of more informationWhen you've successfully booted your system from your emergency repair/recovery tool, make note of any unusual steps you had to take. Store that information with your emergency boot media (DVD/CD, flash drive, whatever), and put both in a safe place. A bit of preparation now could prevent a lot of headaches later — if or when it all hits the fan!
As a last step, undo the changes you made to your UEFI settings, restoring them to their original configuration.
That's it! You're done. You can now have the comfort of UEFI's benefits for routine operation, plus the confidence that you can bypass the UEFI when needed.