Choose Windows/Linux boot managers from within the UEFI?

halfpower · 04-30-2023, 12:07 PM

I'm buying a new laptop, and I'm not totally sure how dual booting works in 2023. A long time ago, Windows would overwrite GNU boot loaders.

With UEFI, am I able to install multiple boot managers, and then choose which one is run when booting? I'm assuming that the multiple boot managers are all located on the same drive. Should I plan to reinstall GRUB if it is periodically overwritten?

BW-userx · 04-30-2023, 02:09 PM

efibootmgr and grub are two completely different entities. they do not interrupt each other per se. still its install windows first then linux. but newer MB should have a hot key to display the efi boots available to the user to get back into linux but if you do not want to have to keep hitting that hot key each time you boot then grub or refind is another boot UEFI systems software that is easy to use too. it as the other OS is managed by efibootmgr

example

Code:

userx4@ubuntu-haha:~$ efibootmgr
BootCurrent: 0006
Timeout: 0 seconds
BootOrder: 0006,0000,0005,0004,0003,0002,0001,0012,0013,0014,0015,0016,0017,0018,0019
Boot0000* ubuntu
Boot0001* rEFInd Boot Manager <<---- rEFInd UEFI boot manager
Boot0002* Windows Boot Manager
Boot0003* slackware-15.0
Boot0004* mx
Boot0005* void
Boot0006* slackware-15.0+
Boot0010  Setup
Boot0011  Boot Menu
Boot0012* NVMe: SPCC M.2 PCIe SSD                      
Boot0013* ATA HDD: Samsung SSD 870 EVO 2TB                 
Boot0014* ATAPI CD:
Boot0015* USB HDD: SanDisk Cruzer Blade
Boot0016* USB CD:
Boot0017* PCI LAN:
Boot0018* USB LAN:
Boot0019* USB FDD:

syg00 · 04-30-2023, 06:14 PM

Quote:

Originally Posted by halfpower

With UEFI, am I able to install multiple boot managers, and then choose which one is run when booting? I'm assuming that the multiple boot managers are all located on the same drive. Should I plan to reinstall GRUB if it is periodically overwritten?

Yes
Yes - if you resist the temptation to allocate a separate EFI partition for linux.
No.

If grub is installed after the Windows loader, it will present a multi-boot menu including both. Occasionally I see Windows resetting the default boot loader back to itself - this can be simply fixed from the firmware menus (aka BIOS screens), or from efibootmgr if you can get into a linux terminal. The former is simplest.

yancek · 05-01-2023, 04:53 AM

Which Linux distribution are you installing? Are you installing it on the same drive as windows? If not, you need to make certain to boot the Linux system in UEFI mode selected in the BIOS and install and create an EFI partition on the 2nd (Linux) drive as mentioned above. Some Linux systems (Ubuntu) will install EFI files to the first EFI partition which is usually the windows partition regardless of the selection you make during the install so that could be a problem but is easily fixed. Using separate drives for each OS simplifies things as you can then select either from the BIOS firmware to boot.

halfpower · 05-01-2023, 10:51 AM

Quote:

Originally Posted by yancek

Which Linux distribution are you installing? Are you installing it on the same drive as windows?

I'll probably install Ubuntu. I might have multiple Linux installations, and potentially multiple Windows installations too. At the moment, I'm thinking about installing it on the same drive as Windows.

pan64 · 05-01-2023, 11:25 AM

One boot (EFI) partition is enough, but probably you need to configure it manually. My windows has its own boot partition, but not used, because I have a common one for everything (and in case of a BIG trouble I can use that boot partition too).