Fix the Windows 10 boot loader
I have a problem fixing the Windows 10 boot loader. I tried booting to the Windows 10 usb installer and making repairs starting from there. I have tried the solution suggested here: How to repair a Windows 10 boot loader from Windows. I have also tried a detailed solution here: http://www.fixedbyvonnie.com/2013/12/how-to-repair-the-efi-bootloader-in-windows-8/. Nobody solved the problem for me.
The history behind the problem is as follows: I initially installed Windows 8.1 on my main boot SSD. Then I distribute and install Arch Linux on the second partition in the same unit. Then I installed Windows 10 on the Arch Linux installation. Then I deleted the Windows 8.1 partition and expanded it again so that Windows 10 was the only operating system installed on the unit. (Then I added the second one with Antergos Linux in it). This installation sequence seems to have left the Arch Gummiboot boot loader in the unit, although if I just boot the drive directly, I always download directly to the Windows boot loader. so I didn't even realize that the Linux gummiboot loader still exists.
I have tried to configure the GPU step to function [https://www.reddit.com/r/pcmasterrace/comments/3lno0t/gpu_passthrough_revisited_an_updated_guide_on_how/] and I cannot make Windows work on the Virtual Machine, and I have determined it looks like the boot loader . I tried several methods to fix this (as above), but nothing worked. So I looked at the SSD where Windows 10 was installed and I saw that there is still an ext4 partition (next to the FAT32 partition, where Windows has the UEFI boot loader). I deleted the ext4 partition and put the "boot" sign on the fat32 partition. After doing this, now Windows doesn't only work on virtual machines, it no longer works, but can't boot directly to Windows. I am now receiving an error "PROCESS1_INITIALIZATION_FAILED" at startup.
I entered the fat32 partition and found that there is still a gummiboot directory. I tried to delete it, but it made no difference. Then I deleted all the files on the FAT32 partition and tried the solution in the first paragraph again. Still nothing works. Even though I now have 6 different entries (all of which don't work) from the Windows boot loader when I enter the BIOS from the motherboard.
Is there a way to resolve this, besides reinstalling Windows 10 completely? And, if I have to reinstall Windows 10, is there a way to save the current partition where is the actual installation of Windows 10 (as opposed to the EFI / boot partition) and throw it into the new installation? (And how do you delete all Windows 10 bootloader entries from the BIOS?)
Assuming Windows is installed on a GPT disk.
In order to successfully start Windows 10 (also Windows 8.1 / 8/7) in UEFI firmware, you need 3 partitions on a GPT-style disk:
EFI system partition (usually 100MB - 500MB)
Partitions ordered by Microsoft (exactly 128MB)
Windows partition (at least 20 GB for 64-bit Windows)
Finally you can have a separate "recovery" partition.
The presence of the first three partitions mentioned is mandatory or, if not, Windows cannot start.
The command to repair the boot loader + BCD + boot loader and write the boot entry to NVRAM is bcdboot.exe -
bcdboot N: \ Windows / s Z:
where N: is the Windows partition and Z: it is the partition of the EFI system. (Then, you must repair the recovery loader separately with the ReAgentC.exe command).
You can also use the bootrec.exe command in the recovery environment to repair the boot (it doesn't always work, but also fixes the recovery boot).
It goes without saying that you have to start the Windows installation / recovery media (USB / DVD) using EFI boot.
UEFI boot does not use the log boot partition and MBR to boot, but can help rewrite the MBR (it must be a protective MBR on the GPT disk) using the bootsect.exe command if the Linux installation has manipulated the MBR. Windows doesn't like the "mixed" MBR format on GPT disks.