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nixpkgs/nixos/lib/qemu-flags.nix
Matthew Bauer 47b56e7c19 runInLinuxVM, test-driver: use -cpu max instead of -cpu host
This appears to avoid requiring KVM when it’s not available. This is
what I originally though -cpu host did. Unfortunately not much
documentation available from the QEMU side on this, but this appears
to square with help:

$ qemu-system-x86 -cpu help
...
x86 host                  KVM processor with all supported host features
x86 max                   Enables all features supported by the accelerator in the current host
...

Whether we actually want to support this not clear, since this only
happens when your CPU doesn’t have full KVM support. Some Nix builders
are lying about kvm support though. Things aren’t too slow without it
though.

Fixes https://github.com/NixOS/nixpkgs/issues/85394

Alternative to https://github.com/NixOS/nixpkgs/pull/83920
2020-08-21 23:42:07 -05:00

31 lines
1.2 KiB
Nix

# QEMU flags shared between various Nix expressions.
{ pkgs }:
let
zeroPad = n:
pkgs.lib.optionalString (n < 16) "0" +
(if n > 255
then throw "Can't have more than 255 nets or nodes!"
else pkgs.lib.toHexString n);
in
rec {
qemuNicMac = net: machine: "52:54:00:12:${zeroPad net}:${zeroPad machine}";
qemuNICFlags = nic: net: machine:
[ "-device virtio-net-pci,netdev=vlan${toString nic},mac=${qemuNicMac net machine}"
"-netdev vde,id=vlan${toString nic},sock=$QEMU_VDE_SOCKET_${toString net}"
];
qemuSerialDevice = if pkgs.stdenv.isi686 || pkgs.stdenv.isx86_64 then "ttyS0"
else if pkgs.stdenv.isAarch32 || pkgs.stdenv.isAarch64 then "ttyAMA0"
else throw "Unknown QEMU serial device for system '${pkgs.stdenv.hostPlatform.system}'";
qemuBinary = qemuPkg: {
x86_64-linux = "${qemuPkg}/bin/qemu-kvm -cpu max";
armv7l-linux = "${qemuPkg}/bin/qemu-system-arm -enable-kvm -machine virt -cpu host";
aarch64-linux = "${qemuPkg}/bin/qemu-system-aarch64 -enable-kvm -machine virt,gic-version=host -cpu host";
x86_64-darwin = "${qemuPkg}/bin/qemu-kvm -cpu max";
}.${pkgs.stdenv.hostPlatform.system} or "${qemuPkg}/bin/qemu-kvm";
}