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What I did:

  • I created using gparted a fresh GPT partition table and partitions as described below
  • Then installed Windows 10 on a fresh machine, did some basic settings, all working nicely... also after 2-3 reboots...
  • Then installed Ubuntu-MATE 18.04 (with "something else" aka custom options, also to get LUKS encryption). Also initial settings and working nicely... also after reboot.

But now I can no longer boot into Windows. What I get first is the grub loader, as usual:

enter image description here

Booting into Ubuntu from here works fine. But if I pick Windows Boot Manager option however, I get this:

enter image description here

And none of the options lead anywhere. (Either you end up back in the grub menu. Or in regular BIOS settings.)

I am using a GPT partition table, so no more worries with extended/logical/primary partions,...

I am using EFI System Partition version of Grub. Explicitly set as boot mode in BIOS (before all else). Litmus test also confirms:

$> [ -d /sys/firmware/efi ] && echo UEFI || echo BIOS
UEFI

Here are my partitions:

$> lsblk
    NAME           MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
    …
    sda              8:0    0 447,1G  0 disk
    ├─sda1           8:1    0   512M  0 part  /boot/efi
    ├─sda2           8:2    0    16M  0 part
    ├─sda3           8:3    0    80G  0 part
    ├─sda4           8:4    0   3,8G  0 part  /boot
    ├─sda5           8:5    0 332,3G  0 part
    │ └─sda5_crypt 253:0    0 332,3G  0 crypt /
    └─sda6           8:6    0  30,5G  0 part  /mnt/transfer
  • sda1 is the EFI System Partition as said
  • sda2 and sda3 are the Win10 partitions (sda2 with 16M is this MSR aka msftres flag) helper partition, which you either provide with gparted or Windows Setup will automatically create it during install. sda3 with 80G is the actual Windows 10 partition.
  • sda4 is holding the linux kernel (and whatever else is needed outside encryption) and sda5 the crypted LUKS partition. – Done this setup successfully on many other machines. Nothing unusual per se. And working nicely, as said.
  • sda6 is a harmless vfat32 transfer partion, non-bootable, no OS stuff

Question: What do I have to do?

Reboot my Windows Boot Stick and go for (Microsofts idea of) “repair“? (or will that smash my Ubuntu side?)

By the way: Do I have to go through "Windows Loader" at all? Or is it possible, to make a direct "Load Windows 10" entry directly in the grub loader resp. the ESP? (Yes, I have yet to grasp, how these two relate)

And if yes, how? Boot from my USB live bootstick... ?

Under Ubuntu, I do see stuff under /boot/grub, but that truly resides on sda4 (no links, no mountpoints as far as I can see!). Do I edit things there and somehow „deploy“ it to the EFI system partion aka sda1?

Or by what other means can I edit the ESP?

The web is clogged with old info about MBR, Win 7/8, BIOS Grub stuff... hard to find what is really relevant:-/

Update I

The „deploy“ I am looking for is update-grub? also in the EFI-ESP world.(?) Add Windows 10 to GRUB OS list

One suspect

On a prior attempt (full fresh install) I noticed an abnormaly in partition numbering. I did sda 1-6 with gparted as pictured above.

When running the Windows System Install (Bootstick) and took the built in partition chooser/editor, it looked like this:

Drive 0 Partition 1:  512 MB   Type: System
Drive 0 Partition 2:  16 MB    MSR
Drive 0 Partition 3:  366 GB   Primary <-- that is sda5 !!
Drive 0 Partition 4:  4 GB     Primary
Drive 0 Partition 5:  76 GB    Primary <-- taht is sda3 !!

I could clearly tell this mistake by volume size.

So, to go along and reduce Windows' choice, I deleted Partition 3 to 5, just create a 80 (or 76) GB one instead and did the windows install. Which then worked correct.

Thereafter the Ubuntu bootstick for installing, I added Partition 4-6 back in. But perhaps precisely that made Windows “rethink” its odd partition numbering and it is now pointing to the wrong place? So the Windows ESP entry tries to run Windows from drive 0 partition 3 which by its own odd conception is sda5(?)

So the fix might be outside Grub in the Windows-information on the ESP drive? So I have to fix the how-to-boot-Windows information on the ESP, apparently known as BCD? (wild ass guess)

Frank N
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    Grub only boots working Windows. And that also means Windows cannot be hibernated. Windows fast start up sets the hibernation flag, so fast start up must be off. Note Windows updates may turn it back on: http://askubuntu.com/questions/843153/ubuntu-16-showing-windows-10-partitions. You should be ble to directly boot Windows from your UEFI one time boot menu. Same key you used to boot USB flash drives. – oldfred Aug 22 '19 at 22:18
  • @oldfred Going through F12 → pick boot device →Windows Boot Manager (the only windowsy choice) → same blue result as above. :-/ – Frank N Aug 23 '19 at 07:28
  • @FrankNocke There is no mistake in the partition sizes, it's a difference on how tools number partitions. In Linux the partition table entry is used to number the partition, in the Windows tool the physical location of the partition on the disk is used. sda1 is the partition which is defined in the first entry in the partition table, but the partition itself could be physical located behind sda2 which is defined in the second entry in the partition table. Different tool > different output ! – mook765 Aug 23 '19 at 12:37
  • You can try f12 and I think with Windows it is f8 to get into the Windows internal repair console. Otherwise use your Windows repair flash drive or installer's repair console. It not you need help on a Windows site as this is Ubuntu only. – oldfred Aug 23 '19 at 14:34

0 Answers0