F35 install doesn't find existing Windows installation

[Matthew Saltzman]

I have a Lenovo Yoga X1 (2nd generation), on which I was happily
running a dual boot of the original Windows 10 installation that came
with the machine and Fedora 34, which I had upgraded through a few
versions of Fedora.

This time, I decided to do a fresh install of Fedora 35 (to try out
BTRFS), but when the installation finished, there was no option to boot
Windows. The Windows data partition, Microsoft reserved partition, and
recovery partitions are all still in place. I attempted to use grub-
customizer to add a chainloader entry pointing to the Windows, but it
displays "Error building boot sequence. Check parameters!"

Gparted shows the Windows partition and the EFI partitio both have
bootable and esp flags set.

Thanks in advance!

How can I get my Windows system to be accessible again?
-- 
Matthew Saltzman
School of Mathematical and Statistical Sciences
Clemson University
mjs AT clemson DOT edu

[Barry Scott]

>  On 6 Nov 2021, at 18:12, Matthew Saltzman <mjs(a)clemson.edu&gt;
> wrote:
>  
>  I have a Lenovo Yoga X1 (2nd generation), on which I was happily
>  running a dual boot of the original Windows 10 installation that came
>  with the machine and Fedora 34, which I had upgraded through a few
>  versions of Fedora.
>  
>  This time, I decided to do a fresh install of Fedora 35 (to try out
>  BTRFS), but when the installation finished, there was no option to boot
>  Windows. The Windows data partition, Microsoft reserved partition, and
>  recovery partitions are all still in place. I attempted to use grub-
>  customizer to add a chainloader entry pointing to the Windows, but it
>  displays "Error building boot sequence. Check parameters!"
>  
>  Gparted shows the Windows partition and the EFI partitio both have
>  bootable and esp flags set.
>  
>  Thanks in advance!
>  
>  How can I get my Windows system to be accessible again? 
I think this is what you are looking for:

https://unix.stackexchange.com/questions/512253/modify-grub-to-dual-boot-...

Also if you reboot and hit the key for the BIOS boot menu you should see windows listed.

Barry



>  -- 
>  Matthew Saltzman
>  School of Mathematical and Statistical Sciences
>  Clemson University
>  mjs AT clemson DOT edu
>  
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[Samuel Sieb]

On 11/6/21 11:12, Matthew Saltzman wrote:
>  This time, I decided to do a fresh install of Fedora 35 (to try out
>  BTRFS), but when the installation finished, there was no option to boot
>  Windows. The Windows data partition, Microsoft reserved partition, and
>  recovery partitions are all still in place. I attempted to use grub-
>  customizer to add a chainloader entry pointing to the Windows, but it
>  displays "Error building boot sequence. Check parameters!"
>  
>  Gparted shows the Windows partition and the EFI partitio both have
>  bootable and esp flags set.
>  
>  Thanks in advance!
>  
>  How can I get my Windows system to be accessible again? 
If you're using EFI, you're better off using the BIOS boot selection 
menu for that anyway.

[Jonathan Billings]

On Nov 6, 2021, at 14:12, Matthew Saltzman <mjs(a)clemson.edu&gt; wrote:
>  
>  I attempted to use grub-
>  customizer to add a chainloader entry pointing to the Windows, but it
>  displays "Error building boot sequence. Check parameters!" 
For the record, grub-customizer doesn’t work on a default Fedora system, which uses the
BootloaderSpec (blscfg) setting in GRUB2.  You can disable it but I’d suggest just
dropping the tool for Fedora systems. (It seems the upstream maintainers aren’t interested
in Fedora, firmly entrenched in the Ubuntu world.)

You are better off using some of the other suggestions in this thread.

—
Jonathan Billings

[Chris Murphy]

On Sat, Nov 6, 2021 at 2:12 PM Matthew Saltzman <mjs(a)clemson.edu&gt; wrote:
>  I have a Lenovo Yoga X1 (2nd generation), on which I was happily
>  running a dual boot of the original Windows 10 installation that came
>  with the machine and Fedora 34, which I had upgraded through a few
>  versions of Fedora.
>
>  This time, I decided to do a fresh install of Fedora 35 (to try out
>  BTRFS), but when the installation finished, there was no option to boot
>  Windows. 
 Did you install Fedora on the same physical drive as Windows? And was
a 2nd drive involved in the installation? And what do you get for
'efibootmgr -v' ?

There are some edge cases where you get what you describe, and it
suggests the initial grub2-mkconfig at the end of installation didn't
find the Windows boot loader.

There's also a gotcha with recent installations of Windows 10 which
automatically encrypt the Windows installation and sequester the
encryption key in the TPM. The only way the key is revealed is when
measured boot indicates the system isn't compromised. The problem is
that booting shim+grub results in measured boot failure when choosing
the Windows boot entry, and while Windows does boot, it also asks for
the recovery key for the drive. The alternative is use the firmware's
built-in boot-manager (boot selection menu) to choose Windows. On my
Lenovo laptop you can get to this menu with F9 (or press enter at the
logo screen, which gets you a function key lookup chart superimposed
on the splash, which shows F9). And from there choose the Windows Boot
Manager.


-- 
Chris Murphy