On Wed, 2017-11-08 at 11:25 -0700, Chris Murphy wrote: > 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 grub2-install is obsolete in this world now, do not use it 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. Thanks for the detailed answer. In the meantime, I did manage to boot the Windows partition directly by tweaking the BIOS, although doing it via Grub would be preferable. With the imminent release of F27, I might take the plunge and just install it directly as UEFI, though I don't know if I can do that without a laborious backup and restore. I normally just upgrade using dnf but this would presumably not work here. poc _______________________________________________ users mailing list -- users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to users-leave@xxxxxxxxxxxxxxxxxxxxxxx
