On Sun, Oct 22, 2017 at 8:03 AM, Patrick O'Callaghan <pocallaghan@xxxxxxxxx> wrote: > I have a new external drive with Windows 10, cloned from my working > QEMU/KVM setup under F26. I want the option of continuing to use it as > a VM, or occasionally dual-booting directly into Windows. The VM is set > up to use UEFI but my host is running under BIOS, so I need to change > one of them to match the other. I prefer to change the host to UEFI as > that is the preferred method for running VMs. > > So how do I go about it? If I simply boot using UEFI I get the EFI menu > with a bunch of block devices and no \EFI directory, which I think > means that I need to do something specific in Fedora. Is this some > magic incantation with Grub? The Grub man pages are not clear. GRUB for BIOS vs GRUB for UEFI are completely different. The commands are different, where the bootloader goes is different, the contents and location of the grub.cfg is different. Etc. It is possible to do, I've done it a few times, but each time I did it differently based on the prior experience, and inevitably I fucked something up in each of those. It was always a case of "oh fuck, that thing, goddamnit" It's over a dozen steps. This is the outline version: 1. Convert MBR to GPT using gdisk 2. Add ESP (likely involves shrinking a file system) 3. update /etc/fstab to include /boot/efi (if you want, I hate this but I also hate persistently mounting /boot) 4. Mixed boot -> load the UEFI GRUB bootloader from live media, get to grub CLI to find the BIOS grub.cfg, hack the cfg so it'll boot UEFI. 5. dnf install grub-efi shim 6. wipe the first 440 bytes of LBA 0 7. grub2-mkconfig pointed to new location on ESP 8. dracut -f 1-3 are easier done while booting live media, and of course the fs resize is several substeps on its own 4 you have to do so the system is booted in UEFI mode so that all the efi sysfs stuff is available for grub2-mkconfig to create a proper cfg; offhand I think the main thing that's needed here is to change linux16 to linuxefi and initrd16 to initrdefi 5 is the actual installation of the bootloaders, both shim and grub; grub2-install is obsolete in this world now, do not use it 6. (nuke the site from orbit, only way to be sure) 7. self explanatory 8. enough has changed you probably need to do it, in fact it's plausible you get a fail at step 4 without a uefi specific initramfs but hey maybe not; maybe hacking on the rescue grub entry is better as that is a no-host-only initramfs It's pretty much like the two firmwares result indifferent sub architectures. -- Chris Murphy _______________________________________________ users mailing list -- users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to users-leave@xxxxxxxxxxxxxxxxxxxxxxx
