how to install pop!_os alongside windows

Question

I would like to install pop!_os (basically a reskin of Ubuntu with some convenience features added) alongside windows 10. So far, I have installed windows 10, using about half the space on my ssd and leaving the rest unallocated, to be used by pop!_os.

If I remember correctly, the installation dialog of Ubuntu had some preconfigured option "install ubuntu alongside windows". Unfortunately, the pop!_os installation doesn't offer this. They do have an official guide on how to properly format partitions for installation: https://pop.system76.com/docs/dual-booting-windows/

The guide says to:

• shrink the existing partition to make room for pop!_os (done)
• create a small 512mb partition for EFI, a big one for / and one at the end of the unused space, for swap.
• tell the installer how they should be used and continue with the installation

At this point I'm confused. My partitions look like this:

The OEM Partition is not mentioned in the guide, but the guide does say that EFI should be at the beginning of the drive. Should I remove the OEM partition? Also, according to the pop!_os guide, EFI should be 512mb. Here it is just 100mb.

How should I proceed with the installation?

I was about to just allocate the unused space for root and swap and tell pop!_os to use the existing EFI as EFI. But to avoid losing the time invested in setting up windows, I thought I would ask here first.

UPDATE:

I tried to proceed with the installation by creating root and swap in the unused space and telling the installer to use the existing EFI as EFI. Unfortunately it complains that the partition is not big enough:

At this point it seems as if I have to resize the EFI partition, is that correct? I seem to remember reading somewhere that it should also be possible to just create a second EFI and use the startup boot menu to select the one you want to boot from.

Also, I read online that EFI needs to be extended at its back, which means shrinking the following partition. This shouldn't be a problem in my case, since the Windows installation is followed by unused space. Should I just move the windows partition backwards and try to extend EFI?

Solution

EFI should be at the beginning of the drive

Wrong. EFI is identified by its partition ID and not by its placement.

Should I remove the OEM partition?

No, since it can be used for reinstalling the original Windows 10 in case of catastrophic error.

according to the pop!_os guide, EFI should be 512mb. Here it is just 100mb.

If 100 MB works for you, then leave the EFI partition as it is. If any installation or upgrade will require more than that, it will automatically allocate a new and larger EFI partition (or fail - but I haven't seen this case yet).

Comments

[lhk]

hm, the laptop came blank, without any OS. I bought win10 online and installed it myself. So 'OEM' is rather misleading. Maybe I should merge those two partitions, OEM and EFI, to make sure EFI has enough space? If I install pop!_os and select the existing EFI to be used as EFI again, how does it know that windows already exists? Does it somehow append the new installation to the existing data? So if I delete the existing OEM and EFI to create a bigger one, will it forget windows?

[harrymc]

The "OEM" partition then seems to be the Windows Refresh/Reset partition, I still recommend leaving it alone (it's too small to bother). Most attempts at merging the EFI end up with a complete re-install, so don't. The Linux install just adds itself as a small subfolder into the EFI, it's the UEFI firmware that knows that there are more than one. In principle 100 MB should really be enough, but Windows sometimes forces it to 512 MB, no need to take the risk of doing it yourself.

[lhk]

unfortunately the installer complains that the EFI size is not big enough...

[harrymc]

It really abuses it somewhat. Just to remark that Ubuntu is available on WSL via the Microsoft Store without these problems. Resolution: (1) Reduce the C partition from inside Windows, (2) Boot a third-party partition editor and move C down over the new unallocated space so it is placed after the EFI partition, (3) Enlarge the EFI partition.

[lhk]

WSL is a nice tip but since 95% of my time are spent in Linux, if this doesn't work, the fallback will be only Linux, no windows at all.

[harrymc]

Note: Apologies, no need to reduce the Windows partition.

[lx07]

If you are proposing a second EFI partition for Linux note that while allowed by UEFI spec Windows 7 installer will fail if there is more than one - not sure about later Windows versions - see 2 EFI partitions on one HDD possible?. Moving C and increasing size the current one may be preferable.

[Radical Edward]

only one efi partition is fine and i was not proposing a second one.