Microsoft → [WIN8] UEFI booting linux from Windows boot manager

Is it possible to boot linux or other non-Microsoft operating system with the Windows boot manager on a UEFI box? And, if so, how?

The documentation on BCDEDIT seems opaque. The documentation at the EasyBCD site does not seem to mention this case, as far as I could see.

I know about BOOTSECTOR, and how to use that for booting another system in legacy BIOS mode. I would like to find out if it is possible to do the equivalent in UEFI mode, where boot sectors are not normally used.

At present, I do have the linux boot manager (grub2-efi) able to boot Windows, though I have to disable secure boot for that to work. I would like to find out how to do it the other way; that is, to set Window 8 as the primary system and have a boot menu there which allows me to select linux.

Last I checked Microsoft holds the keys for secure boot so you'll have to live with secure boot disabled, just like it was in the old days.

"Thanks to Microsoft's Windows 8 UEFI (Unified Extensible Firmware Interface) Secure Boot there was no easy way to boot Linux, or any other operating system, on Windows 8 PCs. Now, there are two ways, the recently released Linux Foundation (LF) UEFI secure boot system and Matthew Garrett's shim system to boot Linux on these PCs. Soon, there will be only one unified way".

From this thread:

»Linux Devs Working On Uniting Windows 8 Secure Boot Fixes

I'm not a Linux user so maybe I misunderstand but after reading the thread and the articles it appears to me that with unification of the two current methods that a Windows 8 user will be able boot Linux with UEFI on and by unifying the two current workarounds that this will make it easier for the user. This is good news especially after Dell told me that I cannot keep secure boot turned off (so I could eventually boot Linux) as that will result in a boot which hangs at Dell logo, is difficult to resolve, and requires keeping secure boot always on to avoid another hang. (I had turned off secure boot shortly after getting this new machine and everything seemed fine for about a month and then suddenly one day I did a routine reboot and the computer hung at Dell logo).

Is ths firstly a question about Secure Boot or a question about hooking up a non-Windows boot loader to the Windows boot manager?

I read it as the latter, especially given the mention of BOOTSECT, the pre-UEFI solution. Other commentors are climbing on the Secure Boot soapbox a little prematurely, I think.

Does this posting answer the question adequately? It's for Windows 8, but perhaps the actual boot mechanism is the same in Win 7.

»superuser.com/questions/ ··· -manager

Yes, you are reading it correctly. The other responders are not.No, I'm afraid that does not help at all. It is oriented toward an MBR/Legacy BIOS setup, rather than a UEFI setup.

i think that is the way to handle the situation, to switch the BIOS-settings to "use legacy bios" (whatever you call it)..

here is a link for some more information:

»www.google.com/search?co ··· ch&gbv=1

But that's a backward step. If the system came with Windows setup for UEFI, and without reinstall disks, then Windows won't work in legacy mode.

It will work just fine with secure boot disabled. And it's supposed to boot any OS that can be booted from a USB device, preferably a pen drive.

But what is the "it" that you are talking about here.

On my Windows 7 system, which is not UEFI, I have an entry in the Windows boot manager menu that can boot my linux install on the same computer.

What I am looking for, is the magical incantation needed to tell Windows 8 on a UEFI box, so that the Windows boot manager will have a menu entry that boots linux.

Thus far, there has been nothing useful in this thread. I've spent a lot of time searching the web for answers, and have not found anything useful. My best guess, at this stage, is that it can't be done. I'm hoping that somebody will prove me wrong.

I spent a little time searching the web after reading the original post, and came up empty. I agree that surely this ought to be simple to do: but my sympathy ain't much help.

quote:

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What I am looking for, is the magical incantation needed to tell Windows 8 on a UEFI box, so that the Windows boot manager will have a menu entry that boots linux.

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That, I do not know.

This is how you boot Linux. (somewhat circuitous, I know)
See »www.geek.com/articles/mo ··· 0130211/

Change Secure Boot Control:
Settings -> Change PC Settings -> General -> Advanced Startup [Restart Now] -> Troubleshoot -> Advanced Options -> UEFI Firmware Settings -> Restart (after restart) Sercure Boot Control -> Disabled

Let me expand a little on this.

I setup linux on my UEFI box. It provides a nice boot menu that I can use to boot either grub or linux.

There's also a menu provided by the BIOS - on a Dell, I hit F12 during boot and select which.

But here's the problem. When I install linux, the Windows entry disappears from the BIOS boot menu. However, there is still a Windows entry in the linux menu (grub menu).

So I use the Windows entry from the grub menu. And that takes me into Windows. No problem.

When I next try to boot, the Windows entry is back in the BIOS menu, and the linux entry has gone. I can only boot Window.

As best I understand it, when I install linux, that simply adds linux to the BIOS boot menu and makes it the default. When I reboot, the BIOS erases the entry for Windows, making the linux entry the only one seen by the BIOS.

Presumably Windows does not like not being in the BIOS menu, so it puts itself back as default. And on the next boot, the BIOS removes the linux entry.

I could live with that, if there were a way to boot linux from the Windows boot manager (much like there is a way to boot Windows from the linux boot manager). But there doesn't seem to be a way to do that.

There is a workaround for the problem. I can create a second EFI partition, and setup linux to use the second EFI partition for booting. When I do that, the BIOS doesn't erase anything and both systems can work, though I have to use the linux boot menu for this.

Creating a second EFI partition seems contrary to the design intention, where a single EFI partition is supposed to be shareable by multiple operating systems.

The Windows documentation explains how to boot other systems. But this all seems oriented toward booting other Windows systems using NTLDR as a legacy booter. There's no mention of booting another system that is defined to EFI.

If I use:

BCDEDIT /enum all /v

I can see that there is already an entry there for the boot code for linux. It is labelled as a "firmware application". I added that to the Windows boot manager menu, but the entry was ignored and no menu appeared.

There are other firmware applications, such as the memory tester, that are listed as being in the tools menu. I have not tried adding the linux booter to the tools menu. Perhaps if I were to do that, I could get a menu by hitting F8 during a windows boot.

So that's the current state of my knowledge. My best guess is that I cannot do what I wanted, so I will have to make do with the workaround.