Dual boots from a single physical drive

churin said:

Thank you for your trying to help me. I have not finished my troubleshooting yet.
I am going to go back to where I could directly boot into W10 from the BIOS Boot Menu. I can do this by using a clone disk I created a couple of steps before the last one.

I just do not understand what your problem is. Let's put things in simple terms.

As @NavyLCDR has sorted out, you can now boot from the windows boot manager and choose W8 or W10.

You only have one drive, and both OSs are on same drive.

The normal configuration is 1 EFI partition with no need to enter bios.
Why on earth do you need multiple efi boot partitions.

That ONLY MAKES SENSE when OSs are on separate physical drives in case one drive fails. That does not apply if only one drive.

So explain exactly why you wish to boot from W10 from bios rather than Wimdows Boot Manager?

NavyLCDR said:

I think I am just going to let @zbook sort it out. Good day.

Yep I do not see any point in carrying on.

MaloK said:

Props to @NavyLCDR, I didn't think this was possible at all.

Why is all this necessary. No shade intended to @NavyLCDR or all the others who contributed to this thread. I have benefitted multiple times from this advice in this forum.

Honestly, I'm not sure I understand all the fuss here. I have one large (1 TB) NVMe main drive. On that drive is my "production" Windows+Programs partition, plus 3 "scratch" Win 10 partitions. I used to have a Win 7 partition, but I upgraded that. I also have my data partition, in a separate Windows partition, for multiple reasons.

I use EasyBCD and it just works. I have turned off the "Metro" bootloader. So when I reboot I get a list of all four partitions (by name). After 30 seconds, it auto boots to the production Windows.

Nothing could be easier.

@NavyLCDR
I wonder where did you get the info that you can have 2 EFI System partitions on the same disk ? your advice given to the OP will never work. In post #27 you clearly stated that your setup is not the same as his ie. you have 2 EFI partitions on the same disk but 2nd Windows is on another disk. Completely different scenario, your setup works, for now, but will eventually lead to unexpected result and sometimes might cause the system to be unbootable.
1 - Even though you can create multiple EFI partitions on the same disk but the EFI Firmware SPEC will only allow one EFI System partition on any single disk.
2 - Having 2 EFI Partitions on the same disk means you will have 2 partitions with the same Partition ID ie. {c12a7328-f81f-11d2-ba4b-00a0c93ec93b} and you will have 2 copies of BCD for the same disk. At boot time, EFI firmware will not know which BCD to store the settings from.
@churin
As I understand, you want:
1 - Both Windows 10 and Windows 8 on the only SSD in your PC for faster speed.
2 - Bypass the Dual Boot Menu
3 - Boot to Windows 10 by default
4 - On occasion, Use F12 to access boot menu to boot Windows 8

The only way to accomplish this, you'd need to:
1 - Delete the last EFI System partition on the SSD that you created earlier
2 - Shrink D drive by 100MB and create a new EFI System Partition
3 - run bcdboot to set the first EFI partition to boot Windows 10 only
4 - run bcdboot to set the newly created EFI System partition on D to boot Windows 8 only.
5 - Reset the CMOS to clear all the remnants from the EFI Firmware, then set to boot Windows 10 first as default.6 - Done

NavyLCDR said:

I just try to help people do what they want to do. I tend not to question why they want to do it. I, too, would simply set up a dual boot menu with my main OS set as default, my seldom used OS as the secondary option, and timeout set to 3 seconds. But, to some, I guess the 3 second wait is just too long.

@NavyLCDR.

I think of you as one of the really valued contributors to this forum. So please take this question as honest, not a criticism, and certainly no disrespect. Quite the opposite.

A person with your reputation has earned a position of "guru" or "leader." May I respectfully, very respectfully ask if, and I'm not sure I'm wording this right, can you state what are "best practices." That is, someone may be trying to "solutionize" an issue in their question, and they need a gentle push towards a different approach. An approach that is cleaner and simpler, and probably more robust.

I hope I have been able to state my question in a simple way that gets to the meaning of my question. I am most definitely NOT trolling.