[SOLVED] GRUB legacy /UEFI

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[SOLVED] GRUB legacy /UEFI

Postby rychok » Jun 19th, '19, 02:47

I got laptop with Windows 10 on hdd and open space for m2 drive, so I bought m2 and without a lot of thinking formatted it with msdos partition table.
I have tried few distros looking for one that will handle pretty new hardware. At that point Mageia 7 is working without problems (6.1 couldn't see any video card ).
Now I started looking for possibility of dual boot, but Windows is on UEFI and Mageia on legacy boot.
I tied
Code: Select all
menuentry 'Windows 10' {
    insmod part_gpt
    insmod ntfs
    search --no-floppy --set=root --fs-uuid 0430-8EA2
    chainloader (${root})/EFI/Microsoft/Boot/bootmgfw.efi
}

But this give me "signature" error - there is no safeboot option in BIOS, the error looks like GRUB message, I have seen someone mention, that there is possibility of disabling GRUB signature checking, but it was only one place.
I have some kind of dual boot without entering BIOS by enabling legacy boot and setting it as first choice, and second is UEFI using
Code: Select all
menuentry 'Windows 10' {
    insmod part_gpt
    insmod ntfs
    search --no-floppy --set=root --fs-uuid 0430-8EA2
    chainloader +1
}

In this case at first I'm getting error that there is no boot device, after hitting Enter computer reboots using second option from BIOS settings and goes to UEFI device which is Windows, next boot brings GRUB menu again.

I'm just wandering if someone found way to boot both OSs in this kind of scenario, also maybe this way is going to be good enough for someone that got himself into same situation, and does not want to reinstall working system.
Last edited by rychok on Jun 25th, '19, 02:06, edited 3 times in total.
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Posts: 59
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Re: GRUB legacy /UEFI

Postby benmc » Jun 19th, '19, 22:22

Mga7 should have installed with grub2.

issue you appear have is trying to boot a UEFI Windows install when the system is in legacy mode.

you are going to have to change your Mageia drive partition format to GPT or your windows drive to msdos.
Backup everything first (goes without saying).
shut down Windows , not hibernate or fast start and remove your Windows drive.
you need to see if your hardware supports booting a non-windows UEFI system.
there are likely some bios switches that need taking care of, secure boot-off, boot from otherOS-on...etc
If you can successfully install UEFI Mageia, reconnect the Windows drive and make sure the system now boots to grub.
if you decide to convert your Windows drive to msdos, no changes needed to your bios, but reverse the above instructions i.e, legacy Windows, remove the Mageia drive ...etc
if so, great. login to Mageia and run
Code: Select all
update-grub2
from a root terminal.
it should detect the Windows drive and add an entry.



reboot and check both entries are there and work.

if not report back here
Last edited by isadora on Jun 20th, '19, 01:21, edited 1 time in total.
Reason: Topic moved into appropriate sub-forum.
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Re: GRUB legacy /UEFI

Postby rychok » Jun 21st, '19, 00:31

Code: Select all
update-grub2

detects only Linux kernels from m2 drive, by the way this is the drive the GRUB is located.
The system boot setting setup in control center also has checked option to detect other system, but is unable to do ao.
I do not know the actual difference in process of loading OS in legacy and UEFI, also the BIOS role in it or different modules of GRUB that are required to do so, therefore when BIOS and GRUB are set to use one way the switch to other method is not really possible. At least this is what I found on different forums. Many of the them were few years old, so my question was a little probing if anything changed.
rychok
 
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Re: GRUB legacy /UEFI

Postby benmc » Jun 21st, '19, 02:18

if updating grub is not detecting the windows drive , can you check if the bios harddrive setting achi or raid-0 for the windows drive?
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Re: GRUB legacy /UEFI

Postby rychok » Jun 21st, '19, 03:55

The drive is in AHCI mode, and you can not change that, because the other option will erase drives - based on BIOS warning.
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Re: GRUB legacy /UEFI

Postby martinw » Jun 22nd, '19, 23:46

You could try making your existing Mageia installation EFI-bootable. First, in the MCC, got to Local disks / Manage disk partitions. Click on your existing EFI system partition (ESP) on the HDD, and set the mount point to /boot/EFI. Then boot the classical installer ISO in UEFI mode, and select the option to upgrade your system. That should quickly run through to the summary screen, where you can select the bootloader and check that it is configured correctly. Finish the upgrade, and your system should now be dual-bootable in EFI mode.
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Re: GRUB legacy /UEFI

Postby rychok » Jun 25th, '19, 02:06

Thank For your response,
I know I can reinstall Mageia to EFI mode, I was just curious if GRUB can handle this, also like I said I have some kind of dual boot through GRUB and BIOS.
Anyway I will mark this thread as Solved.
rychok
 
Posts: 59
Joined: Jul 9th, '13, 03:03

Re: [SOLVED] GRUB legacy /UEFI

Postby martinw » Jun 25th, '19, 09:33

My point was that you could add an EFI bootloader to your existing Mageia installation - no need to reinstall.

As far as I know, it is not possible to boot in legacy mode and then chain to an EFI bootloader.
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