How can I dual boot ubuntu and windows 10 (with separate efi paritions)

I already created the partitions. One is ext4(the /), other is swap, and other is fat32 with boot flag. In the installer, I choosed /dev/sdb5 as the local to install the bootloader(grub). I did it, rebooted, but in bios boot tab I can’t see ubuntu, just windows boot manager. In F7 (boot menu) ubuntu actually appears, but it’s duplicated. You can see more details here: Duplicate "ubuntu" entries in bios boot menu and no option in bios "boot" tab to initiate on ubuntu

I tried to ask the same question on reddit and askubuntu, but no answer yet

I do not dual boot in Years, but what people have told on the telegram group is that in Windows 10, there is a fast boot configuration, that need to be disabled to Grub be able to work, the other thing is that W10 is installed in UEFI, and then so is any linux distro.
this tutorial give you a very good step by step on what is needed to be done for dual booting.

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Thanks, but the type of dual boot that I am trying is different. I actually don’t want grub to boot windows, only ubuntu, because if I want to go to windows, I can do it thought the boot menu. I think in this way is safer, because windows updates will never break grub or any boot manager

Sorry cant help you on that, may be if you do two different uefi partitions you could get the behaviour you looking for. me i use windows 10 in a VM it is safer and i can create several snapshots to control the points i will return when w10 brakes things

Search UEFI here, been there, done that except that I wanted to dual boot.

Could you use a second drive to dual boot with? I have two distinct/separate drives in my Thinkpad.
Perhaps I’ve missed something…

With the Thinkpad, you need to disable some things in its Boot to get it to work properly with Ubuntu distro. Check in this forum there is further detail within.
Also depends on Thinkpad you are using but on mine, to get a manual boot menu I press Enter as it boots. I dont see the problem with having a dual boot as long as you prioritize Ubuntu as the first boot item.