How to go back to Legacy Boot?

[shmu26]

I have a dual-boot system with Windows 10 (GPT partitioning) and MX Linux. It is set up as EFI boot.
I want to go back to legacy (MBR) boot, because I am having issues with virtual machines based on my Windows system. (I have a VM created by Physical-to-Virtual, and another one that I am trying to boot by raw access to the Windows installation. Both have booting problems in VirtualBox.)

I enabled legacy boot in the BIOS, but I can't get it to boot Windows that way. I tried fixing the boot with Windows recovery media, and with Macrium Reflect recovery media, but no go. Windows doesn't want to boot from legacy.
What to do?

 

[notabot]

I have a dual-boot system with Windows 10 (GPT partitioning) and MX Linux. It is set up as EFI boot.
I want to go back to legacy (MBR) boot, because I am having issues with virtual machines based on my Windows system. (I have a VM created by Physical-to-Virtual, and another one that I am trying to boot by raw access to the Windows installation. Both have booting problems in VirtualBox.)

I enabled legacy boot in the BIOS, but I can't get it to boot Windows that way. I tried fixing the boot with Windows recovery media, and with Macrium Reflect recovery media, but no go. Windows doesn't want to boot from legacy.
What to do?

Is secure boot disabled in Windows ?

 

[shmu26]

Is secure boot disabled in Windows ?

Yes.

 

[Local Host]

You can't use a GPT partition in Legacy, you need to convert it to MBR.

You can convert a partition from MBR to GPT without reformat, but the opposite is not possible (at least natively).

 

[shmu26]

You can't use a GPT partition in Legacy, you need to convert it to MBR.

You can convert a partition from MBR to GPT without reformat, but the opposite is not possible (at least natively).

I was afraid of that.
What happens if I reformat, and then restore a system image on it? Does that put it back to GPT?

 

[Local Host]

I was afraid of that.
What happens if I reformat, and then restore a system image on it? Does that put it back to GPT?

I don't think it will work, as Windows itself needs to be setup for either MBR or GPT, is the reason Microsoft made a built-in tool to convert the from MBR to GPT with no data loss (no options for the opposite, as MBR is obsolete).

 

[shmu26]

I don't think it will work, as Windows itself needs to be setup for either MBR or GPT, is the reason Microsoft made a built-in tool to convert the from MBR to GPT with no data loss (no options for the opposite, as MBR is obsolete).

Thanks. Sounds like going back to MBR is the nuclear option. I guess I will just stick with my P2V virtual machine that I once created with the VMware standalone converter tool. It gives you an option for MBR boot in the conversion, and that worked for me in VirtualBox. (For optimum performance, you need to do a second conversion, from VMDK to VDI.)

I posted about my booting issues on the VirtualBox forum, maybe they will get back to me...