My XPS is currently W10 x64 with secure boot enabled.
I would like to temporarily boot it to a Win 7 x32 OS on an SD card that I created with WintoUSB with MBR and UEFI.
1st = is that possible?
If not, I can put it on a USB stick, but I also have a Linux USB stick that I can't boot either because of Secure Boot, I think. I have set boot options to Thorough but apparently, I need to disable Secure Boot.
When I go to do that I get orange and red screens indicating that I should not do that and asking if I REALLY WANT TO DO THAT. The last time that happened, I wasn't told what the outcome was going to be and had to start from scratch to get back. Since this is not specifically telling me that I can roll this back without reinstalling my whole system, I want to verify that this is the procedure to allow this kind of boot and that I can roll it back.
Although Windows 7 can be booted in UEFI mode, it does not support Secure Boot because its bootloader was never signed -- so it definitely won't work with Secure Boot enabled. Windows 7 also does not fully support the UEFI spec. Even when booted in UEFI mode, it retains some Legacy BIOS dependencies, so you have to keep Legacy Option ROMs (sometimes called UEFI CSM/Compatibility Support Module) enabled in order for it to start. Normally that option is only enabled to allow a system to support booting "true" Legacy BIOS environments as well as UEFI environments, but with Windows 7 you need it enabled even when booting it in UEFI mode. (This incidentally is why Windows 7 doesn't work in a Hyper-V Gen 2 VM, which only supports "full UEFI" OSes and does not allow Legacy BIOS dependencies.) And when Legacy Option ROMs is enabled, you can't enable Secure Boot.
Apart from that, there's the reality that the XPS 13 9370 is much newer than Windows 7 and therefore there aren't any Windows 7 drivers available for it, so even if you do get Windows 7 to boot, you might find that some of your hardware doesn't properly or at all. Running the 32-bit version also means you'll be limited to 4GB of RAM total and no more than 2GB of RAM for any single process. And that's all before even considering possible Windows 7 activation issues due to being booted from external, portable media (technically only Windows To Go installations are licensed to be installed on portable devices, which requires special enterprise licensing) and the question of whether Windows 7 even supports being booted specifically from an SD card at all. And finally there's the fact that Windows 7 stops receiving security updates from Microsoft next month, so it's not really a good idea to keep running it even if you can.
Back to Secure Boot, most Linux distros do not support it, at least not without some extensive manual effort because Secure Boot by default only trusts bootloaders signed by Microsoft. Microsoft has actually signed the bootloaders of some Linux distros, such as Ubuntu, so those distros can actually boot with Secure Boot enabled out of the box. But with most Linux distros, you need to either disable Secure Boot or import additional signing authority certificates into your firmware so that your system's Secure Boot mechanism will trust whoever signed the Linux bootloader you're trying to use.
All that said, you can absolutely disable Secure Boot and enable Legacy Option ROMs without messing up your system or your installed Windows environment. What you CANNOT do is put your system into full Legacy boot mode (assuming that's even possible on the 9370), which will completely disable UEFI boot support. That WILL prevent your existing Windows installation from booting, but even there you can get back to normal by changing those settings back. Same goes for changing between AHCI and RAID mode. There aren't any BIOS settings that will completely destroy your existing Windows installation unless maybe you have a "Secure Erase your hard drive" option in there.
The warning about disabling Secure Boot exists because it is a useful anti-rootkit measure for OSes that support it, because if the bootloader is ever infected by malware, having Secure Boot will cause your system to warn you about that when you boot it. I've seen threads where people have complained that their system will no longer boot because of a warning from Secure Boot saying that the bootloader has failed the integrity check, and some people have told them to work around it by disabling Secure Boot. Well that would technically allow the system to boot (unless the bootloader has been completely corrupted), but if the system DOES boot at that point, you've probably just allowed your system to boot from an infected bootloader. So that advice is a bit like telling someone whose house alarm has just gone off to just go disable it to stop all the noise without bothering to see if maybe a burglar is now in their home.
And fyi, if Secure Boot is ever the reason a system won't boot, the system will make that completely clear. It will specifically say that the bootloader has failed the Secure Boot integrity check, or something along those lines. If you don't see that message, then Secure Boot isn't your issue.
Now it will take me 3 weeks to digest that.
My main reason is that I have ONE program that does not want to run - at least on my computer - under W10.
Others have apparently gotten it to work, but after 3 weeks of trying, I am giving up.
It appears to be a driver issue, but all works under 32 bit W7 = not x64.
@ruggb yes, a driver issue is likely if it works on 32-bit but not 64-bit. But if you just need Windows 7 for a single application, consider running Windows 7 as a virtual machine rather than from an entirely separate device. That will avoid the boot issues and driver issues you are facing or will likely face with trying to run Windows 7 natively on that system, and it would also allow you to run that one application and its Windows environment alongside your existing Windows 10 environment rather than having to switch back and forth between the two. And performance will likely be better since you won't be running from an SD card, which are typically pretty slow. If you have Windows 10 Pro, you have access to Hyper-V for running VMs. If not, then look at VirtualBox, which is free. The XPS 13 9370 would have plenty of horsepower to run a Windows 7 32-bit VM for a single application alongside the Windows 10 environment. Give your VM maybe 1-2 GB of RAM depending on the application's requirements and it should be fine. All you'd need then is a Windows 7 installation ISO. Attach that to the VM's virtual CD/DVD drive, set the VM to boot from that virtual CD/DVD drive, and then install Windows 7 in the VM like you would on any normal system.