2mo ago

Installing Linux distro without breaking Windows install

Solution: When I formatted all my drives to install Linux on one and Windows on the other, I kept both connected and they share EFI boot partition as a result. Every time I reinstall Linux it formats the drive and therefore deletes the Windows's EFI Boot as well. One way is to fix this is to reinstall Windows while disconnecting the drive you have Linux on. Or you can move the boot files if you don't want to do that.

I used this guide: https://forums.tomshardware.com/threads/changing-windows-boot-manager-drive.3571420/post-21561626

Also remember to delete the Microsoft folder in the boot folder on Linux after you’ve checked that the new boot loader is working.

OP:

Currently dual booting as I need Windows for a few tasks and ganes Linux just won’t do. Since setting everything up I’ve reinstalled Linux twice, both times I’ve lost the ability to boot into windows and have needed to reinstall it.

Disk doesn’t show at all in Grub, tried all kinds of things but it just doesn’t show as a bootable OS. It doesn’t show in the boot options in the BIOS or the boot menu for my motherboard. Drive shows up and all the files are still on it. So my guess is the Windows bootloader somehow installs on the same disk that I have Linux on.

I run Linux(Fedora) and Windows on two separate drives.

Windows take forever to install. Anything I can do now to prevent this from happening if I need to reinstall Linux or if I wanna to some distro hopping?

Just to be clear, everything is working right now. But I want to prevent having to reinstall Windows every time I change distro or reinstall my Linux OS

33 comments

Do you have the os-prober package installed? I haven't used Fedora in over a decade, so I don't know if it's a default or not.
- Yes that’s present and working.
  Issue is that my BIOS doesn’t find it either. So something happens when I install a linux distro that breaks the Windows boot loader.
  When I reinstall Windows, I can update the grub and it shows up. (It’s also back in the BIOS after reinstalling)
  
  I was doing some quick research and saw someone suggest installing each OS with the other drive disconnected. That way you can first get each one working individually and there's no chance of one messing with the other's bootloader.
I've had Windows and Linux installed on the SAME drive for decades and don't have this issue. Install Windows first because it WILL fuck up the EFI boot partition, that's inevitable because Windows sucks, then install Linux, use the manual partition option and simply select the existing EFI System partition for the EFI and DO NOT mark format, Linux will then install and leave the Windows boot loader in the EFI partition undisturbed.
Linux WILL overwrite the boot block to start grub instead of the Windows boot loader, but most Linux distros will automatically add a chain boot loader entry to the grub menu to allow you to boot Windows, at least Debian and Redhat derived distros will do this, probably a more manual process in Arch derived distros.
If it does become necessary to install Whendoze after Linux, you can use boot-repair to automatically fix the EFI System partition Windows fucked up or you can boot off of a flash drive, and fix it manually.
Adding the solution to your post is a classy move, and I approve
- The solution offended some people it seems like. But I’m sure I’m not alone in creating a problem like this for myself. 😂
have you tried updating GRUB, or replacing GRUB with something like rEFInd?
- Yeah, I have to do that after reinstalling Windows again. Just did and that solves the issue of getting it into Grub so that I wont have tot go through the BIOS.
  But when I install Linux, the Windows boot disappears from the BIOS too. Even tried to find it trough the «Repair» options when booting from a Windows USB, but it’s just gone.
  Is it possible that Windows and Linux shares UEFI partitions even if they’re on different drives?
I saw that you said windows is on SSD and Linux on NVME. Sounds like modern PC. In my case, I use the motherboard's boot menu. It asks which drive I want to boot from. If I need windows, I choose the drive which has it. If I need to reinstall, I remove the other drive. I don't need grub to probe other drives. Plus, grub menu books super clean.
Fucking hell that’s a real pain in the arse solution you have there.
If you have two drives then one will be sda and the other will be sdb. Install Windows first on sda (which will mean the boot sector is on sda) then install linux to sdb.
When you get to the part in the Linux installation process where it asks where you want the boot partition tell it to install on sda.
Then anytime you want to install and try a different distro just install to sdb with the boot sector on sda and grub will always detect and add Windows to the boot menu.
Ran that configuration for 10yrs zero issues.
- This solution took all about 2 minutes. Now it won’t matter what I do when I reinstall Linux. My Windows boot is not on that same drive any more.
  If I would have known my Windows boot was on the M.2 drive I install Linux on, I would not tell the Linux installer to format that drive, obviously.
  It’s an Issue I created myself by not thinking about Windows’ limitations. But this solution is pretty quick if you already reinstalled Windows again.
Did you install os-prober so that GRUB can look for other OSes?
You could use a separate drive for Linux.
- I am. Windows is on a 2.5" Sata SSD while Linux is on an Nvme M.2 drive
  
  Hmm. Windows shouldn't be putting anything on the Linux drive. Maybe disconnect the other drive before installing Windows.
Last I checked, if you want to dual boot, you HAVE to install Windows first (or disconnect the linux drive before hand), otherwise it will mess with your boot partitions on all drives.
Windows is also prone to mess with boot partitions randomly long after the initial install, so be wary
What Linux distro are you using? To make it not erase the Windows boot manager from the EFI partition simply manually partition, and do NOT mark the EFI partition for formatting, then Linux will add it's own but NOT erase Windows.
- I prefer to just move the Windows boot loader so that I don’t have to even think about it. Having Windows’ EFI completely separated is a much better solution in my opinion. But both solutions work all the same.
First of all: You don't have to reinstall Windows to get it's bootmgr EFI and supporting files back into the ESP. Installing those from the CLI in from a booted install media is possible, I did it before. You can even install all of Windows manually if you ever need to, it's just annoying to do with the windows command line tools.
Secondly: I'm not familiar with all distro installers, but surely you can just not format the ESP? Worst case scenario you'd have to use manual disk formatting I guess, but it's not that difficult.
Thirdly: You said Grub doesn't show the disk. If you mean the Grub command interface didn't show the disk, then the issue is deeper, at a UEFI or hardware level. If you mean there are no boot entries for a Windows install to be selected, then it could be that they were not generated because the Windows bootmgr EFI was not found when Grub got installed. Sometimes just booting back into Linux and running os-prober again might be enough, if the Windows bootmgr EFI is still around. On my distro the os-proper is automatically run when I run grub-mkconfig -o /boot/grub/grub.cfg
I've always used a shared ESP for my dual boot systems and I certainly don't reinstall one OS as the result of a change with the other.
- I know, it’s just way easier to reinstall.
  I didn’t know Windows installed it’s boot loader on the Linux drive until after I formatted the drive. So see point 1.
  Grub didn’t show the Windows boot loader because it was deleted. After reinstalling Windows it shows up again.
  You comment comes off as pretty hostile, why?
  
  Ah that makes sense then. I was confused why you would wipe your ESP over and over when it was shared.
  I don't know why it comes off as hostile, it wasn't intended that way. Sorry for not expressing it better!
  If the last sentence came across badly, that was more meant to be incredulous that people accept all these workaround instead. There are other comments in here that go to ridiculous lengths to enforce separation, like using the UEFI boot menu to select a disk manually. To me even having two ESPs seems overly cautious, and against the design philosophy. Sharing one ESP is really not an issue (at least as long as you know you're doing it, as you unfortunately found out the hard way).
Isn't it easier to boot using the bios ? zero maintenance. zero chance of an update fucking it up.
- Not sure what you mean here. This issue is related to moving Windows’s boot files to a different drive. Only relevant if you want to use the automatic partition option while installing a distro.
  Booting in BIOS won’t make any difference whatsoever if the boot loader is gone.
  
  I daily drive Aurora (which is an image based distro) from an m2 caddy on my work laptop.
  These kind of distros do not allow for manual partitioning, so they just use the whole drive.
  My BIOS is set to prioritize Aurora.
  My m2 caddy can be used on any other hardware and Aurora will boot just fine.

33 comments