nixpkgs/modules/testing/test-instrumentation.nix

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# This module allows the test driver to connect to the virtual machine
# via a root shell attached to port 514.
{ config, pkgs, ... }:
with pkgs.lib;
let
# Urgh, `socat' sets the SIGCHLD to ignore. This wreaks havoc with
# some programs.
rootShell = pkgs.writeScript "shell.pl"
''
#! ${pkgs.perl}/bin/perl
$SIG{CHLD} = 'DEFAULT';
print "\n";
exec "/bin/sh";
'';
in
{
config =
# Require a patch to the kernel to increase the 15s CIFS timeout.
mkAssert (config.boot.kernelPackages.kernel.features ? cifsTimeout) "
VM tests require that the kernel has the CIFS timeout patch.
" {
jobs.backdoor =
{ startOn = "startup";
stopOn = "never";
script =
''
export USER=root
export HOME=/root
export DISPLAY=:0.0
source /etc/profile
cd /tmp
exec < /dev/hvc0 > /dev/hvc0 2> /dev/ttyS0
echo "connecting to host..." >&2
stty -F /dev/hvc0 raw -echo # prevent nl -> cr/nl conversion
${pkgs.socat}/bin/socat stdio exec:${rootShell}
'';
respawn = false;
};
boot.initrd.postDeviceCommands =
''
# Using acpi_pm as a clock source causes the guest clock to
# slow down under high host load. This is usually a bad
# thing, but for VM tests it should provide a bit more
# determinism (e.g. if the VM runs at lower speed, then
# timeouts in the VM should also be delayed).
echo acpi_pm > /sys/devices/system/clocksource/clocksource0/current_clocksource
'';
boot.postBootCommands =
''
# Panic on out-of-memory conditions rather than letting the
# OOM killer randomly get rid of processes, since this leads
# to failures that are hard to diagnose.
echo 2 > /proc/sys/vm/panic_on_oom
# Coverage data is written into /tmp/coverage-data.
mkdir -p /tmp/xchg/coverage-data
# Mount debugfs to gain access to the kernel coverage data (if
# available).
mount -t debugfs none /sys/kernel/debug || true
'';
# If the kernel has been built with coverage instrumentation, make
# it available under /proc/gcov.
boot.kernelModules = [ "gcov-proc" ];
# Panic if an error occurs in stage 1 (rather than waiting for
# user intervention).
boot.kernelParams =
[ "console=tty1" "console=ttyS0" "panic=1" "stage1panic=1" ];
# `xwininfo' is used by the test driver to query open windows.
environment.systemPackages = [ pkgs.xorg.xwininfo ];
# Send all of /var/log/messages to the serial port.
services.syslogd.extraConfig = "*.* /dev/ttyS0";
# Disable "-- MARK --" messages. These prevent hanging tests from
# being killed after 1 hour of silence.
services.syslogd.extraParams = [ "-m 0" ];
# Don't run klogd. Kernel messages appear on the serial console anyway.
jobs.klogd.startOn = mkOverride 50 "";
# Prevent tests from accessing the Internet.
networking.defaultGateway = mkOverride 150 "";
networking.nameservers = mkOverride 150 [ ];
system.upstartEnvironment.GCOV_PREFIX = "/tmp/xchg/coverage-data";
};
}