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nixos/qemu-vm: make it possible to use UEFI without bootloaders

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`useEFIBoot` is somewhat misleading, but we should make it possible to
enable UEFI environment / firmware without buying into a bootloader.

This makes it possible.
This commit is contained in:
Raito Bezarius 2023-04-26 18:28:31 +02:00
parent 1d5ff2163e
commit 6e8248c8b2
1 changed files with 18 additions and 10 deletions
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28
nixos/modules/virtualisation/qemu-vm.nix
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@ -169,18 +169,26 @@ let
# Create a directory for exchanging data with the VM.
mkdir -p "$TMPDIR/xchg"
${lib.optionalString cfg.useBootLoader
${lib.optionalString cfg.useEFIBoot
''
# Expose EFI variables, it's useful even when we are not using a bootloader (!).
# We might be interested in having EFI variable storage present even if we aren't booting via UEFI, hence
# no guard against `useBootLoader`. Examples:
# - testing PXE boot or other EFI applications
# - directbooting LinuxBoot, which `kexec()s` into a UEFI environment that can boot e.g. Windows
NIX_EFI_VARS=$(readlink -f "''${NIX_EFI_VARS:-${config.system.name}-efi-vars.fd}")
${lib.optionalString cfg.useEFIBoot
''
# VM needs writable EFI vars
if ! test -e "$NIX_EFI_VARS"; then
cp ${systemImage}/efi-vars.fd "$NIX_EFI_VARS"
chmod 0644 "$NIX_EFI_VARS"
fi
''}
# VM needs writable EFI vars
if ! test -e "$NIX_EFI_VARS"; then
${if cfg.useBootLoader then
# We still need the EFI var from the make-disk-image derivation
# because our "switch-to-configuration" process might
# write into it and we want to keep this data.
''cp ${systemImage}/efi-vars.fd "$NIX_EFI_VARS"''
else
''cp ${cfg.efi.variables} "$NIX_EFI_VARS"''
}
chmod 0644 "$NIX_EFI_VARS"
fi
''}
cd "$TMPDIR"