upgrading to windows 10 with dual boot

I have a pc with both windows and linux, when i upgrade my windows to windows 10 will this cause issues with my grub?

I don't have linux installed within windows when i installed both i created a seperate partition for each and installed each separately

 

It is possible that it will break the alternate boot loader, yes.

 

This is a great question Nexus! I hadn't thought about this, as I haven't dual-booted in years. But I do remember that the order of installation of OS is paramount. Windows first, Linux last, as the Windows bootloader only sees Windows, while GRUB sees all systems.

If you must dual-boot, I think Adrynalyne is right...it is POSSIBLE that the Win10 upgrade will mess with the GRUB2 bootloader. I just don't KNOW for certain. It will depend entirely on how Win10 interacts with the existing MS bootloader. If Win10 replaces your existing bootloader (like a fresh install) it WILL cause issues with your existing GRUB; if Win10 uses your existing bootloader (like an upgrade) it may or may not cause issues, depending on the command chain that Win10 requires. My suspicion is that, worst case, GRUB may only present your Linux boot option, because your previously existing GRUB can't see the end of the new "chain" to boot Win10. If this is the case, this scenario is easily fixed by booting into your Linux installation, opening a terminal session, and typing

Code:

sudo grub-update

which will allow grub to update itself and to present the correct options at boot time.

FWIW, as I became less and less reliant on MS-based programs, dual-booting became an impractical time-waster for me and I decided to install Windows as a guest VM on my Linux host and eliminated my Windows partition to reclaim that space for my Linux OS. Is this a possible solution for you also? This would eliminate any potential GRUB issues with dual boot options.

Hopefully, someone else who dual-boots with Win10 will drop by and say for certain what happens with GRUB. Good news is that, even if Win10 corrupts GRUB, it is easily fixed by booting with a LiveCD/USB (just like trying out a new Linux distro before installation), or by a specialty GRUB rescue disk. Either way, you have options!

Good instructions for that can be found here:
https://www.linux.com/learn/tutorials/776643-how-to-rescue-a-non-booting-grub-2-on-linux/

 

These days, I've found it safer to keep separate drives and boot them individually via boot order. This keeps eash drive with its own bootloader and prevents installs from affecting the other drives.

 

I get the same complete isolation of OSs by using a fairly old boot manager, Grub4DOS, which can hide partitions from each other at boot. It's the best way to mix Windows and Linux on the same drive as any of the OSs can be changed, deleted or added to with no effect at all on the others as every installed OS is completely self contained, unlike with Windows dual boots. For good measure it also boots bootable ISOs.

 

i actually thought about using windows through VM but another family member occasionally uses this pc.

We all know linux isn't for everyone so i kept that windows partition there for that reason... that and the fact that i still kind of have to use some windows software for some things