Hello there,
Dell XPS-15-9560 laptop (SSD drive, UEFI, secure boot off).. Windows 10 pre-installed, CentOS7 installed in a separate partition and running for months w/o issue. Don't know what happened but at reboot yesterday (not even booted in Windows, just rebooted), grub has disappeared, booted in Windows by default, which apparently has taken over the UEFI boot.
By booting from a USB drive w/ CentOS7 LiveGnome, I could use its grub command prompt to inspect the UEFI of the local SSD drive, see that the centos/ sub-directory and files are still there.
/boot/efi/EFI/centos/: BOOT.CSV BOOTX64.CSV fonts grub.cfg grub.cfg.1501243846.rpmsave grub.cfg.1505469290.rpmsave grubenv grubx64.efi mmx64.efi shim.efi shimx64-centos.efi shimx64.efi
maybe /boot/efi/EFI/Boot/ contents has been altered?
/boot/efi/EFI/Boot/: bootx64.efi fbx64.efi
I had a backup of the full efi partition (`dd`) but it's outdated and I feel it's a bad idea to restore the partition from it.
Still from this "external" grub prompt, I could boot into my CentOS7 using: configfile (hd0,gpt1)/EFI/centos/grub.cfg
At least I know how to get back to it :-).
But now, how could I give the UEFI control back to grub? Is there a grub2 or grubby command I can run to make grub the default? I've read a lot and still cannot figure out exactly what to do or don't dare running commands that could make things worse.
And I have the feeling the at next Windows boot, I may need to do it again..
Regards,