Re: Double boot (Windows & Debian) with UEFI mode
On Mon 06 Dec 2021 at 11:56:08 (+0000), Andrew M.A. Cater wrote:
> On Mon, Dec 06, 2021 at 10:56:29AM +0100, frantal@libero.it wrote:
> > unfortunately, nothing David suggested worked, so I finally set it on in the bios Legacy (via F12) and then reinstalled Debian.
> >
> > Now if I turn on, Grub appears with Debian that starts (even if it takes a while to boot) and if I want to use Windows, at boot, I have to click F12 and select boot with UEFI and then Windows 10 starts.
> >
> > I tried to install os-prober on Debian, but it is already installed and doing update-grub, but Windows is not shown (Probably because it is inserted in the UEFI boot).
> >
> > Is there any way to fix this mess?
>
> That _definitely_ won't work. If one OS is installed using UEFI, then both
> need to be. Can you delete the Debian you've installed / reboot and use
> rescue mode in expert mode.
Sorry, but that generalisation gets trotted out over and
over again. Of course, those who actually practise it on
systems where it works know that it's not true and sigh,
while the world keeps turning.
> An expert install of Debian will allow you to specify where the boot files
> are. There is an option to install to a fallback location that should be
> found by any UEFI firmware. If you do that, it should work, and os-prober
> should also pick up the existing Windows installer.
>
> I think when I did this last time, I installed Debian first in UEFI mode and
> left space for Windows. Installing Windows thereafter it found the ESP
> partition and installed Windows boot files there. I think it might have
> made Windows default boot and ignored Debian.
Where people use mixed UEFI/BIOS booting, the reports I've read
indicate that Windows is typically the original, ab initio,
system, and linux is installed after shrinking W's large
partition in order to create linux partitions, including a
BIOS Boot partition (notably present in the OP's system) for
their GPT disk.
> Rebooting Debian rescue mode and reinstalling grub and os-prober then found
> Windows and put the items into grub so that it is sorted out.
I assume those instructions were what you intended to post in
https://lists.debian.org/debian-user/2021/12/msg00104.html
but they didn't make it.
Cheers,
David.
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