qemu_kvm is only built for one architecture, so it's smaller and takes
MUCH less time to build if it has to be built from source. And this
module doesn't support running a VM for one architecture from another
architecture, so the one architecture is all we'll need.
pathsInNixDB isn't a very accurate name when a Nix store image is
built (virtualisation.useNixStoreImage); rename it to additionalPaths,
which should be general enough to cover both cases.
Add the `useNixStoreImage` option, allowing a disk image with the
necessary contents from the Nix store to be built using
make-disk-image.nix. The image will be mounted at `/nix/store` and
acts as a drop-in replacement for the usual 9p mounting of the host's
Nix store.
This removes the performance penalty of 9p, drastically improving
execution speed of applications which do lots of reads from the Nix
store. The caveats are increased disk space usage and image build
time.
I realized quite recently that running a test VM - as documented in the
manual - like
QEMU_NET_OPTS='hostfwd=tcp::8080-:80' ./result/bin/nixos-run-vms
doesn't work anymore on `master`. After bisecting I realized that the
introduction of a forward-port option[1] is the problem since it adds a
trailing comma even if no forwarding options are specified via
`virtualisation.forwardPorts`. In that case, the networking options
would look like `-netdev user,id=user.0,,hostfwd=tcp::8080-:80' which
confused QEMU and thus the VM refused to start.
Now, the trailing comma is only added if additional port forwards are
specified declaratively.
[1] b8bfc81d5b
The current name is misleading: it doesn't contain cli arguments,
but several constants and utility functions related to qemu.
This commit also removes the use of `with import ...` for clarity.
... build-vm-with-bootloader" for EFI systems
This reverts commit 20257280d9, reversing
changes made to 926a1b2094.
It broke nixosTests.installer.simpleUefiSystemdBoot
and right now channel is lagging behing for two weeks.
`nixos-rebuild build-vm-with-bootloader` currently fails with the
default NixOS EFI configuration:
$ cat >configuration.nix <<EOF
{
fileSystems."/".device = "/dev/sda1";
boot.loader.systemd-boot.enable = true;
boot.loader.efi.canTouchEfiVariables = true;
}
EOF
$ nixos-rebuild build-vm-with-bootloader -I nixos-config=$PWD/configuration.nix -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/nixos-20.09.tar.gz
[...]
insmod: ERROR: could not insert module /nix/store/1ibmgfr13r8b6xyn4f0wj115819f359c-linux-5.4.83/lib/modules/5.4.83/kernel/fs/efivarfs/efivarfs.ko.xz: No such device
mount: /sys/firmware/efi/efivars: mount point does not exist.
[ 1.908328] reboot: Power down
builder for '/nix/store/dx2ycclyknvibrskwmii42sgyalagjxa-nixos-boot-disk.drv' failed with exit code 32
[...]
Fix it by setting virtualisation.useEFIBoot = true in qemu-vm.nix, when
efi is needed.
And remove the now unneeded configuration in
./nixos/tests/systemd-boot.nix, since it's handled globally.
Before:
* release-20.03: successful build, unsuccessful run
* release-20.09 (and master): unsuccessful build
After:
* Successful build and run.
Fixes https://github.com/NixOS/nixpkgs/issues/107255
The toplevel derivations of systems that have `networking.hostName`
set to `""` (because they want their hostname to be set by DHCP) used
to be all named
`nixos-system-unnamed-${config.system.nixos.label}`.
This makes them hard to distinguish.
A similar problem existed in NixOS tests where `vmName` is used in the
`testScript` to refer to the VM. It defaulted to the
`networking.hostName` which when set to `""` won't allow you to refer
to the machine from the `testScript`.
This commit makes the `system.name` configurable. It still defaults to:
```
if config.networking.hostName == ""
then "unnamed"
else config.networking.hostName;
```
but in case `networking.hostName` needs to be to `""` the
`system.name` can be set to a distinguishable name.
Without this, systemd-boot does not add an EFI boot entry for itself.
The reason it worked before this fix is because it would fall back to
the default installed \EFI\BOOT\BOOTX64.EFI
boot.loader.grub.device` was hardcoded to `bootDevice`, which is
wrong, because that's the device for `/`, and with `useBootLoader`
the boot loader is not on that device.
This bug probably came into existence because of bad naming;
`virtualisation.bootDevice` has description
"The disk to be used for the root filesystem", which is very confusing;
it should be `.rootDevice` then!
Unfortunately, the description is right and the attribute name is wrong,
so it is not easy to change this without deprecation.
This commit ensures that even if you use `useBootLoader` and
`diskInterface == "scsi"`, the created VM can boot through, and can run
`nixos-rebuild afterwards.
It also adds extra commentary to explain what's going on in this module
in general in relation to `useBootLoader`.
xchg is advertised as a bidirectional exchange dir, but file content
transfer from host to VM fails due to caching:
If a file is read in the VM and then modified on the host, subsequent
re-reads in the VM can yield old, cached data.
This is caused by the use of 9p's cache=loose mode that is explicitly
meant for read-only mounts.
9p doesn't provide any suitable cache modes, so fix this by disabling
caching.
Also, remove a now unnecessary sync in the test driver.
