I shrunk Windows partition, freed 100 Gb, installed Ubuntu into it, installed GRUB into into MBS of the first drive and after reboot I got Windows and with no any option to select. Even in BIOS in boot priority config I see that the main drive entitled as Windows.My question is not what to do. I don't want to see these long canvases of text and pictures you can find bu searching on this topic, saying only what authors do not understand what are they doing.My question is what is happening? How BIOS can know operating system? What is boot sequnce in my case and why does MBR code is ignored?UPDATESome authors recommend to run this command under Windows:bcdedit /set {bootmgr} path \EFI\ubuntu\grubx64.efiWhat does it do and how can it help?UDPATE 2I was able to boot my linux partition win Grub for Windows, and currently$ efibootmgrBootCurrent: 0006Timeout: 1 secondsBootOrder: 0005,0004,0003,0002,0000,0001,0006Boot0000  <CENSORED>Boot0001  <CENSORED>Boot0002  Hard Drive Boot0003    CD/DVD Boot0004* Network Card Boot0005* Windows Boot ManagerBoot0006  Grub2Win EFI(I was entering some bad words during experiments)Looks like it just prints some info from EFI partition.
GRUB menu doesn't appear after Ubuntu install alongside with Windows 10
dual boot;grub;uefi;mbr