[SOLVED] Help configuring a new build for Dual Boot Linux/Win-10 ?

[phlp]

I have 2 systems with the following volume configuration

HP Pavilion

WDC 320GB Windows-10 Partitioning: Master Boot Record
Partitions
"System Reserved" /dev/sdb1 607MB NTFS NTFS/exFAT/HPFS Bootable 0ECAA83ACAA82047
"FileSystem" /dev/sdb2 319GB NTFS NTFS/exFAT/HPFS DEE8B6B3E8B688F3
WDC 1TB UBUNTU
Partitions
"FileSystem" /dev/sda1 310MB ext4 linux Not Mounted BA99FE67947EE-931B-4D2AA78304D1
"FileSystem" /dev/sda5 511MB FAT EFI /boot/efi bootable 4E71-EBB6
"FileSystem" /dev/sda6 511MB Ext4 LINUX /boot 687CBE79-C0F2-475F-8B12-D3E07B564DC6
"Swap" /dev/sda7 32GB Swap linux swap cd13ebdd-4631-4cf5-92ae-a73f42b81d0a
"FileSystem" /dev/sda8 300GB Ext4 LINUX / 055b0bb8-6216-4280-84dd-b2d13cb699ce
"FileSystem" /dev/sda9 667GB Ext4 LINUX /home 6f5582a2-9298-4c5e-a4d8-153ae7494cc0

DIY Home Build

WD_BLOCK 500GB UBUNTU Partitioning: GUID partition table
Volumes
"FileSystem" /dev/nvme0n1p1 537MB FAT EFI /boot/efi FF49-F114
"FileSystem" /dev/nvme0n1p2 500GB Ext4 linux / 36d6a217-c9b1-410c-93d9-93a13562d585

I want to move the Win-10 volume to the new system and be able to dual boot it.

After completing the new system build, I installed UBUNTU with only the WD_BLACK volume mounted and then I added the Win-10 volume. System boots directly into UBUNTU and I don't get a GRUB boot query so I can't dual boot.

Next I re-installed UBUNTU with the Win-10 volume wired in but still could not dual boot.

Next I directly booted the Win-10 volume from BIOS setup and got a grub boot error

error: no such device: 687CBE79-C0F2-475F-8B12-D3E07B564DC6
error: Entering rescue mode...
grub rescue>

and as you can see, that UUID is the UBUNTU /boot partition on the HP 1TB volume.

I've google'd and there are so many different hits that I'm leary of trying and much of it is dated material. But I have tried a couple of things.

update_grub - no change

From Windows safe mode command prompt - bootrec /fixMBR - I suspect made things worse, I can't the boot UBUNTU volume alone.

So here's my current state.

On the HP system:

- I can boot into GRUB when the Win-10 volume is present. GRUB can select either Windows
or UBUNTU.

- I can no longer boot the UBUNTU system when the Win-10 volume is removed. I think
the Windows safe mode bootrec command broke that.

On the new system:

- I can't dual boot and I can't boot the Win-10 volume directly.

I suspect the HP BIOS boots the Windows volume whose boot loader has been replaced with GRUB and therefore can boot either Windows or UBUNTU.

I'm guessing that the HP UBUNTU volume has had it's boot sector overwritten with the Win-10 boot loader (from bootrec) and it can't find Windows when the Windows volume is removed. I hoped that an update-grub when booted into UBUNTU would fixup the stand-alone UBUNTU boot loader issue, but apparently not. I can always reinstall, so this is a minor issue though I assume it has an easy fix.

I want the HP system to boot with just the single 1TB UBUNTU volume and the new system to
dual boot Win-10 and UBUNTU. Then I can add a TPM module and upgrade to WIn-11.

I suspect that Partitioning: Master Boot Record vs GUID partition table is a stumbling block but I don't know enough here to understand the issue.

 

[phlp]

I resolved my problem. I converted the Win-10 volume to EFI, it was needed for Win-11 anyway. I used the Microsoft tool mbr2gpt which worked fine. I did get an error about updating an .XML file, but when I looked at the partitions, it had created the EFI partition so I booted the new system with it and it booted successfully. Rebooted UBUNTU and did a update-grub and now the system dual boots.

I reinstalled UBUNTU on the HP volume because I couldn't find anything that would restore it to a bootable config.