linux-kernel-module-cheat/run

#!/usr/bin/env python3

import os
import re
import shutil
import subprocess
import sys
import time

import common
from shell_helpers import LF

class Main(common.LkmcCliFunction):
    def __init__(self):
        super().__init__(
            description='''\
Run some content on an emulator.
'''
        )
        self.add_argument(
            '-c',
            '--cpus',
            default=1,
            type=int,
            help='Number of guest CPUs to emulate. Default: %(default)s'
        )
        self.add_argument(
            '--ctrl-c-host',
            default=False,
            help='''\
Ctrl + C kills the QEMU simulator instead of being passed to the guest.
'''
        )
        self.add_argument(
            '-D',
            '--debug-vm',
            default=False,
            help='''\
Run GDB on the emulator itself.
For --emulator native, this debugs the target program.
'''
        )
        self.add_argument(
            '--debug-vm-args',
            default='',
            help='Pass arguments to GDB. Implies --debug-vm.'
        )
        self.add_argument(
            '--debug-vm-rr',
            default=False,
            help='''
Run the emulator through Mozilla RR, and then start replay with reverse debugging enabled:
https://cirosantilli.com/linux-kernel-module-cheat#reverse-debug-the-emulator
'''
        )
        self.add_argument(
            '--dtb',
            help='''\
Use the specified DTB file. If not given, let the emulator generate a DTB for us,
which is what you usually want.
'''
        )
        self.add_argument(
            '-E',
            '--eval',
            help='''\
Replace the normal init with a minimal init that just evals the given sh string.
See: https://cirosantilli.com/linux-kernel-module-cheat#replace-init
chdir into lkmc_home before running the command:
https://cirosantilli.com/linux-kernel-module-cheat#lkmc_home
'''
        )
        self.add_argument(
            '-F',
            '--eval-after',
            help='''\
Similar to --eval, but the string gets evaled at the last init script,
after the normal init finished. After this string is evaled, you are left
inside a shell. See: https://cirosantilli.com/linux-kernel-module-cheat#init-busybox
'''
        )
        self.add_argument(
            '-G',
            '--gem5-exe-args',
            default='',
            help='''\
Pass extra options to the gem5 executable.
Do not confuse with the arguments passed to config scripts,
like `fs.py`. Example:
./run --emulator gem5 --gem5-exe-args '--debug-flags=Exec --debug' -- --cpu-type=HPI --caches
will run:
gem.op5 --debug-flags=Exec fs.py --cpu-type=HPI --caches
'''
        )
        self.add_argument(
            '--gdb',
            default=False,
            help='''\
Shortcut for the most common GDB options that you want most of the time. Implies:
* --gdb-wait
* --tmux-args <main> where <main> is:
** start_kernel in full system
** main in user mode
* --tmux-program gdb
'''
        )
        self.add_argument(
            '--gdb-wait',
            default=False,
            help='''\
Wait for GDB to connect before starting execution
See: https://cirosantilli.com/linux-kernel-module-cheat#gdb
'''
        )
        self.add_argument(
            '--gem5-script',
            default='fs',
            choices=['fs', 'biglittle'],
            help='Which gem5 script to use'
        )
        self.add_argument(
            '--gem5-readfile',
            default='',
            help='''\
Set the contents of m5 readfile to this string.
https://cirosantilli.com/linux-kernel-module-cheat#gem5-restore-new-script
'''
        )
        self.add_argument(
            '--gem5-restore',
            type=int,
            help='''\
Restore the nth most recently taken gem5 checkpoint according to directory
timestamps.
'''
        )
        self.add_argument(
            '--graphic',
            default=False,
            help='''\
Run in graphic mode.
See: http://github.com/cirosantilli/linux-kernel-module-cheat#graphics
'''
        )
        self.add_argument(
            '--kdb',
            default=False,
            help='''\
Setup KDB kernel CLI options.
See: http://github.com/cirosantilli/linux-kernel-module-cheat#kdb
'''
        )
        self.add_argument(
            '--kernel-cli',
            help='''\
Pass an extra Linux kernel command line options, and place them before
the dash separator `-`. Only options that come before the `-`, i.e.
"standard" options, should be passed with this option.
Example: `./run --arch arm --kernel-cli 'init=/lkmc/poweroff.out'`
'''
        )
        self.add_argument(
            '--kernel-cli-after-dash',
            help='''\
Pass an extra Linux kernel command line options, add a dash `-`
separator, and place the options after the dash. Intended for custom
options understood by our `init` scripts, most of which are prefixed
by `lkmc_`.
Example: `./run --kernel-cli-after-dash 'lkmc_eval="wget google.com" lkmc_lala=y'`
'''
        )
        self.add_argument(
            '--kernel-version',
            default=common.consts['linux_kernel_version'],
            help='''\
Pass a base64 encoded command line parameter that gets evalled at the end of
the normal init.
See: https://cirosantilli.com/linux-kernel-module-cheat#init-busybox
chdir into lkmc_home before running the command:
https://cirosantilli.com/linux-kernel-module-cheat#lkmc_home
Specify the Linux kernel version to be reported by syscall emulation.
Defaults to the same kernel version as our default Buildroot build.
Currently only works for QEMU.
See: http://github.com/cirosantilli/linux-kernel-module-cheat#fatal-kernel-too-old
'''
        )
        self.add_argument(
            '--kgdb',
            default=False,
            help='''\
Setup KGDB kernel CLI options.
See: http://github.com/cirosantilli/linux-kernel-module-cheat#kgdb
'''
        )
        self.add_argument(
            '-K',
            '--kvm',
            default=False,
            help='''\
Use KVM. Only works if guest arch == host arch.
See: http://github.com/cirosantilli/linux-kernel-module-cheat#kvm
'''
        )
        self.add_argument(
            '-m',
            '--memory',
            default='256M',
            help='''\
Set the memory size of the guest. E.g.: `--memory 512M`. We try to keep the default
at the minimal ammount amount that boots all archs. Anything lower could lead
some arch to fail to boot.
Default: %(default)s
'''
        )
        self.add_argument(
            '--quit-after-boot',
            default=False,
            help='''\
Setup a kernel init parameter that makes the emulator quit immediately after boot.
'''
        )
        self.add_argument(
            '-R',
            '--replay',
            default=False,
            help='Replay a QEMU run record deterministically'
        )
        self.add_argument(
            '-r',
            '--record',
            default=False,
            help='Record a QEMU run record for later replay with `-R`'
        )
        self.add_argument(
            '--show-stdout',
            default=True,
            help='''Show emulator stdout and stderr on the host terminal.'''
        )
        self.add_argument(
            '--terminal',
            default=False,
            help='''\
Output directly to the terminal, don't pipe to tee as the default.
With this, we don't not save the output to a file as is done by default,
but we are able to do things that require not having a pipe such as
using debuggers. This option is set automatically by --debug-vm, but you
still need it to debug gem5 Python scripts with pdb.
'''
        )
        self.add_argument(
            '-T',
            '--trace',
            help='''\
Set trace events to be enabled. If not given, gem5 tracing is completely
disabled, while QEMU tracing is enabled but uses default traces that are very
rare and don't affect performance, because `./configure
--enable-trace-backends=simple` seems to enable some traces by default, e.g.
`pr_manager_run`, and I don't know how to get rid of them.
See: http://github.com/cirosantilli/linux-kernel-module-cheat#tracing
'''
        )
        self.add_argument(
            '--trace-stdout',
            default=False,
            help='''\
Output trace to stdout instead of a file. Only works for gem5 currently.
'''
        )
        self.add_argument(
            '--trace-insts-stdout',
            default=False,
            help='''\
Trace instructions run to stdout. Shortcut for --trace --trace-stdout.
'''
        )
        self.add_argument(
            '-t',
            '--tmux',
            default=False,
            help='''\
Create a tmux split the window. You must already be inside of a `tmux` session
to use this option:
* on the main window, run the emulator as usual
* on the split:
** if on QEMU and `-d` is given, GDB
** if on gem5, the gem5 terminal
See: https://cirosantilli.com/linux-kernel-module-cheat#tmux
'''
        )
        self.add_argument(
            '--tmux-args',
            help='''\
Parameters to pass to the program running on the tmux split. Implies --tmux.
'''
        )
        self.add_argument(
            '--tmux-program',
            choices=('gdb', 'shell'),
            help='''\
Which program to run in tmux. Implies --tmux. Defaults:
* 'gdb' in qemu
* 'shell' in gem5. 'shell' is only supported in gem5 currently.
'''
        )
        self.add_argument(
            '--vnc',
            default=False,
            help='''\
Run QEMU with VNC instead of the default SDL. Connect to it with:
`vinagre localhost:5900`.
'''
        )
        self.add_argument(
            'extra_emulator_args',
            nargs='*',
            default=[],
            help='''\
Extra options to append at the end of the emulator command line.
'''
        )

    def timed_main(self):
        show_stdout = self.env['show_stdout']
        # Common qemu / gem5 logic.
        # nokaslr:
        # * https://unix.stackexchange.com/questions/397939/turning-off-kaslr-to-debug-linux-kernel-using-qemu-and-gdb
        # * https://stackoverflow.com/questions/44612822/unable-to-debug-kernel-with-qemu-gdb/49840927#49840927
        #   Turned on by default since v4.12
        kernel_cli = 'console_msg_format=syslog nokaslr norandmaps panic=-1 printk.devkmsg=on printk.time=y rw'
        if self.env['kernel_cli'] is not None:
            kernel_cli += ' {}'.format(self.env['kernel_cli'])
        if self.env['quit_after_boot']:
            kernel_cli += ' {}'.format(self.env['quit_init'])
        kernel_cli_after_dash = ' lkmc_home={}'.format(self.env['guest_lkmc_home'])
        extra_emulator_args = []
        extra_qemu_args = []
        if not self.env['_args_given']['tmux_program']:
            if self.env['emulator'] == 'qemu':
                self.env['tmux_program'] = 'gdb'
            elif self.env['emulator'] == 'gem5':
                self.env['tmux_program'] = 'shell'
        if self.env['gdb']:
            if not self.env['_args_given']['gdb_wait']:
                self.env['gdb_wait'] = True
            if not self.env['_args_given']['tmux_args']:
                if self.env['userland'] is None and self.env['baremetal'] is None:
                    self.env['tmux_args'] = 'start_kernel'
                else:
                    self.env['tmux_args'] = 'main'
            if not self.env['_args_given']['tmux_program']:
                self.env['tmux_program'] = 'gdb'
        if self.env['tmux_args'] is not None or self.env['_args_given']['tmux_program']:
            self.env['tmux'] = True
        if self.env['debug_vm_rr']:
            debug_vm = ['rr', 'record']
        elif self.env['debug_vm'] or self.env['debug_vm_args']:
            debug_vm = ['gdb', LF, '-q', LF] + self.sh.shlex_split(self.env['debug_vm_args']) + ['--args', LF]
        else:
            debug_vm = []
        if self.env['gdb_wait']:
            extra_qemu_args.extend(['-S', LF])
        if self.env['eval_after'] is not None:
            kernel_cli_after_dash += ' lkmc_eval_base64="{}"'.format(self.sh.base64_encode(self.env['eval_after']))
        if self.env['kernel_cli_after_dash'] is not None:
            kernel_cli_after_dash += ' {}'.format(self.env['kernel_cli_after_dash'])
        if self.env['vnc']:
            vnc = ['-vnc', ':0', LF]
        else:
            vnc = []
        if self.env['eval'] is not None:
            kernel_cli += ' {}=/lkmc/eval_base64.sh'.format(self.env['initarg'])
            kernel_cli_after_dash += ' lkmc_eval="{}"'.format(self.sh.base64_encode(self.env['eval']))
        if not self.env['graphic']:
            extra_qemu_args.extend(['-nographic', LF])
        console = None
        console_type = None
        console_count = 0
        if self.env['arch'] == 'x86_64':
            console_type = 'ttyS'
        elif self.env['is_arm']:
            console_type = 'ttyAMA'
        console = '{}{}'.format(console_type, console_count)
        console_count += 1
        if not (self.env['arch'] == 'x86_64' and self.env['graphic']):
            kernel_cli += ' console={}'.format(console)
        extra_console = '{}{}'.format(console_type, console_count)
        console_count += 1
        if self.env['kdb'] or self.env['kgdb']:
            kernel_cli += ' kgdbwait'
            if self.env['kdb']:
                if self.env['graphic']:
                    kdb_cmd = 'kbd,'
                else:
                    kdb_cmd = ''
                kernel_cli += ' kgdboc={}{},115200'.format(kdb_cmd, console)
            if self.env['kgdb']:
                kernel_cli += ' kgdboc={},115200'.format(extra_console)
        if kernel_cli_after_dash:
            kernel_cli += " -{}".format(kernel_cli_after_dash)
        extra_env = {}
        if self.env['trace_insts_stdout']:
            if self.env['emulator'] == 'qemu':
                extra_emulator_args.extend(['-d', 'in_asm', LF])
            elif self.env['emulator'] == 'gem5':
                self.env['trace_stdout'] = True
                self.env['trace'] = 'ExecAll'
        if self.env['trace'] is None:
            do_trace = False
            # A dummy value that is already turned on by default and does not produce large output,
            # just to prevent QEMU from emitting a warning that '' is not valid.
            trace_type = 'load_file'
        else:
            do_trace = True
            trace_type = self.env['trace']

        def raise_rootfs_not_found():
            if not self.env['dry_run']:
                raise Exception('Root filesystem not found. Did you build it? ' \
                                'Tried to use: ' + self.env['disk_image'])
        def raise_image_not_found():
            if not self.env['dry_run']:
                raise Exception('Executable image not found. Did you build it? ' \
                                'Tried to use: ' + self.env['image'])
        cmd = debug_vm.copy()
        if not os.path.exists(self.env['image']):
            if self.env['emulator'] == 'gem5':
                if (
                    self.env['baremetal'] is None and
                    self.env['userland'] is None
                ):
                    # This is an attempte to run gem5 from a prebuilt download
                    # but it is not working:
                    # https://github.com/cirosantilli/linux-kernel-module-cheat/issues/79
                    self.sh.check_output(
                        [
                            self.env['extract_vmlinux'],
                            self.env['linux_image']
                        ],
                        out_file=self.env['image'],
                        show_cmd=True,
                        show_stdout=False
                    )
                else:
                    raise_image_not_found()
            else:
                raise_image_not_found()
        if self.env['emulator'] == 'gem5':
            if self.env['quiet']:
                show_stdout = False
            if not self.env['baremetal'] is None:
                if not os.path.exists(self.env['gem5_fake_iso']):
                    os.makedirs(os.path.dirname(self.env['gem5_fake_iso']), exist_ok=True)
                    self.sh.write_string_to_file(self.env['gem5_fake_iso'], 'a' * 512)
            elif self.env['userland'] is None:
                if not os.path.exists(self.env['rootfs_raw_file']):
                    if not os.path.exists(self.env['qcow2_file']):
                        raise_rootfs_not_found()
                    self.raw_to_qcow2(qemu_which=self.env['qemu_which'], reverse=True)
            os.makedirs(os.path.dirname(self.env['gem5_readfile_file']), exist_ok=True)
            self.sh.write_string_to_file(self.env['gem5_readfile_file'], self.env['gem5_readfile'])
            memory = '{}B'.format(self.env['memory'])
            gem5_exe_args = self.sh.shlex_split(self.env['gem5_exe_args'])
            if do_trace:
                gem5_exe_args.extend(['--debug-flags', trace_type, LF])
            extra_env['M5_PATH'] = self.env['gem5_system_dir']
            # https://stackoverflow.com/questions/52312070/how-to-modify-a-file-under-src-python-and-run-it-without-rebuilding-in-gem5/52312071#52312071
            extra_env['M5_OVERRIDE_PY_SOURCE'] = 'true'
            if self.env['trace_stdout']:
                debug_file = 'cout'
            else:
                debug_file = 'trace.txt'
            cmd.extend(
                [
                    self.env['executable'], LF,
                    '--debug-file', debug_file, LF,
                    '--listener-mode', 'on', LF,
                    '--outdir', self.env['m5out_dir'], LF,
                ] +
                gem5_exe_args
            )
            if self.env['userland'] is not None:
                cmd.extend([
                    self.env['gem5_se_file'], LF,
                    '--cmd', self.env['image'], LF,
                    '--num-cpus', str(self.env['cpus']), LF,
                    # We have to use cpu[0] here because on multi-cpu workloads,
                    # cpu[1] and higher use workload as a proxy to cpu[0].workload.
                    # as can be seen from the config.ini.
                    # If system.cpu[:].workload[:] were used instead, we would get the error:
                    # "KeyError: 'workload'"
                    '--param', 'system.cpu[0].workload[:].release = "{}"'.format(self.env['kernel_version']), LF,
                ])
                if self.env['userland_args'] is not None:
                    cmd.extend(['--options', self.env['userland_args'], LF])
            else:
                if self.env['gem5_script'] == 'fs':
                    if self.env['gem5_restore'] is not None:
                        # https://cirosantilli.com/linux-kernel-module-cheat#gem5-checkpoint-internals
                        cpt_dirs = self.gem5_list_checkpoint_dirs()
                        cpt_dir = cpt_dirs[-self.env['gem5_restore']]
                        cpt_dirs_sorted_by_tick = sorted(cpt_dirs, key=lambda x: int(x.split('.')[1]))
                        extra_emulator_args.extend(['-r', str(cpt_dirs_sorted_by_tick.index(cpt_dir) + 1)])
                    cmd.extend([
                        self.env['gem5_fs_file'], LF,
                        '--disk-image', self.env['disk_image'], LF,
                        '--kernel', self.env['image'], LF,
                        '--num-cpus', str(self.env['cpus']), LF,
                        '--script', self.env['gem5_readfile_file'], LF,
                    ])
                    if self.env['arch'] == 'x86_64':
                        if self.env['kvm']:
                            cmd.extend(['--cpu-type', 'X86KvmCPU', LF])
                        if self.env['baremetal'] is None:
                            cmd.extend(['--command-line', 'earlyprintk={} lpj=7999923 root=/dev/sda {}'.format(console, kernel_cli), LF])
                    elif self.env['is_arm']:
                        if self.env['kvm']:
                            cmd.extend(['--cpu-type', 'ArmV8KvmCPU', LF])
                        if self.env['dp650']:
                            dp650_cmd = 'dpu_'
                        else:
                            dp650_cmd = ''
                        cmd.extend([
                            # TODO why is it mandatory to pass mem= here? Not true for QEMU.
                            # Anything smaller than physical blows up as expected, but why can't it auto-detect the right value?
                            '--machine-type', self.env['machine'], LF,
                        ])
                        if self.env['baremetal'] is None:
                            cmd.extend([
                                '--command-line',
                                'earlyprintk=pl011,0x1c090000 lpj=19988480 rw loglevel=8 mem={} root=/dev/sda {}'.format(memory, kernel_cli), LF
                            ])
                        dtb = None
                        if self.env['dtb'] is not None:
                            dtb = self.env['dtb']
                        elif self.env['dp650']:
                            dtb = os.path.join(
                                self.env['gem5_system_dir'],
                                'arm',
                                'dt',
                                'armv{}_gem5_v1_{}{}cpu.dtb'.format(
                                    self.env['armv'],
                                    dp650_cmd,
                                    self.env['cpus']
                                )
                            )
                        if dtb is not None:
                            cmd.extend(['--dtb-filename', dtb, LF])
                        if self.env['baremetal'] is None:
                            cmd.extend(['--param', 'system.panic_on_panic = True', LF])
                        else:
                            cmd.extend([
                                '--bare-metal', LF,
                                '--param', 'system.auto_reset_addr = True', LF,
                            ])
                            if self.env['arch'] == 'aarch64':
                                # https://stackoverflow.com/questions/43682311/uart-communication-in-gem5-with-arm-bare-metal/50983650#50983650
                                cmd.extend(['--param', 'system.highest_el_is_64 = True', LF])
                elif self.env['gem5_script'] == 'biglittle':
                    if self.env['kvm']:
                        cpu_type = 'kvm'
                    else:
                        cpu_type = 'atomic'
                    if self.env['gem5_restore'] is not None:
                        cpt_dir = self.gem5_list_checkpoint_dirs()[-self.env['gem5_restore']]
                        extra_emulator_args.extend(['--restore-from', os.path.join(self.env['m5out_dir'], cpt_dir), LF])
                    cmd.extend([
                        os.path.join(
                            self.env['gem5_source_dir'],
                            'configs',
                            'example',
                            'arm',
                            'fs_bigLITTLE.py'
                        ), LF,
                        '--bootscript', self.env['gem5_readfile_file'], LF,
                        '--big-cpus', str((self.env['cpus'] + 1) // 2), LF,
                        '--cpu-type', cpu_type, LF,
                        '--disk', self.env['disk_image'], LF,
                        '--kernel', self.env['image'], LF,
                        '--little-cpus', str(self.env['cpus'] // 2), LF,
                        '--root', '/dev/vda', LF,
                    ])
                    if self.env['dtb']:
                        cmd.extend([
                            '--dtb',
                            os.path.join(self.env['gem5_system_dir'],
                                'arm',
                                'dt',
                                'armv8_gem5_v1_big_little_2_2.dtb'
                            ),
                            LF
                        ])
            cmd.extend(['--mem-size', memory, LF])
            if self.env['gdb_wait']:
                # https://stackoverflow.com/questions/49296092/how-to-make-gem5-wait-for-gdb-to-connect-to-reliably-break-at-start-kernel-of-th
                cmd.extend(['--param', 'system.cpu[0].wait_for_remote_gdb = True', LF])
        elif self.env['emulator'] == 'qemu':
            qemu_user_and_system_options = [
                '-trace', 'enable={},file={}'.format(trace_type, self.env['qemu_trace_file']), LF,
            ]
            if self.env['userland'] is not None:
                if self.env['gdb_wait']:
                    debug_args = ['-g', str(self.env['gdb_port']), LF]
                else:
                    debug_args = []
                cmd.extend(
                    [
                        self.env['qemu_executable'], LF,
                        '-L', self.env['userland_library_dir'], LF,
                        '-r', self.env['kernel_version'], LF,
                        '-seed', '0', LF,
                    ] +
                    qemu_user_and_system_options +
                    debug_args
                )
                cpu = 'max'
            else:
                extra_emulator_args.extend(extra_qemu_args)
                self.make_run_dirs()
                if debug_vm:
                    serial_monitor = []
                else:
                    if self.env['background']:
                        serial_monitor = ['-serial', 'file:{}'.format(self.env['guest_terminal_file']), LF]
                        if self.env['quiet']:
                            show_stdout = False
                    else:
                        if self.env['ctrl_c_host']:
                            serial = 'stdio'
                        else:
                            serial = 'mon:stdio'
                        serial_monitor = ['-serial', serial, LF]
                if self.env['kvm']:
                    extra_emulator_args.extend([
                        '-enable-kvm', LF,
                    ])
                    cpu = 'host'
                else:
                    cpu = 'max'
                extra_emulator_args.extend([
                    '-serial',
                    'tcp::{},server,nowait'.format(self.env['extra_serial_port']), LF
                ])
                virtfs_data = [
                    (self.env['p9_dir'], 'host_data'),
                    (self.env['out_dir'], 'host_out'),
                    (self.env['out_rootfs_overlay_dir'], 'host_out_rootfs_overlay'),
                    (self.env['rootfs_overlay_dir'], 'host_rootfs_overlay'),
                ]
                virtfs_cmd = []
                for virtfs_dir, virtfs_tag in virtfs_data:
                    if os.path.exists(virtfs_dir):
                        virtfs_cmd.extend([
                            '-virtfs',
                            'local,path={virtfs_dir},mount_tag={virtfs_tag},security_model=mapped,id={virtfs_tag}' \
                                .format(virtfs_dir=virtfs_dir, virtfs_tag=virtfs_tag),
                            LF,
                        ])
                machines = [self.env['machine']]
                if self.env['arch'] == 'arm':
                    # Needed since v3.0.0 due to:
                    # http://lists.nongnu.org/archive/html/qemu-discuss/2018-08/msg00034.html
                    machines.append('highmem=off')
                machines_cli = []
                for machine in machines:
                    machines_cli.extend(['-machine', machine, LF])
                cmd.extend(
                    [
                        self.env['qemu_executable'], LF,
                    ] +
                    machines_cli +
                    [
                        '-device', 'rtl8139,netdev=net0', LF,
                        '-gdb', 'tcp::{}'.format(self.env['gdb_port']), LF,
                        '-kernel', self.env['image'], LF,
                        '-m', self.env['memory'], LF,
                        '-monitor', 'telnet::{},server,nowait'.format(self.env['qemu_monitor_port']), LF,
                        '-netdev', 'user,hostfwd=tcp::{}-:{},hostfwd=tcp::{}-:22,id=net0'.format(
                            self.env['qemu_hostfwd_generic_port'],
                            self.env['qemu_hostfwd_generic_port'],
                            self.env['qemu_hostfwd_ssh_port']
                        ), LF,
                        '-no-reboot', LF,
                        '-smp', str(self.env['cpus']), LF,
                    ] +
                    virtfs_cmd +
                    serial_monitor +
                    vnc
                )
                if self.env['dtb'] is not None:
                    cmd.extend(['-dtb', self.env['dtb'], LF])
                if not self.env['qemu_which'] == 'host':
                    cmd.extend(qemu_user_and_system_options)
                if self.env['initrd']:
                    extra_emulator_args.extend(['-initrd', self.env['buildroot_cpio'], LF])
                rr = self.env['record'] or self.env['replay']
                if self.env['ramfs']:
                    # TODO why is this needed, and why any string works.
                    root = 'root=/dev/anything'
                else:
                    if rr:
                        driveif = 'none'
                        rrid = ',id=img-direct'
                        root = 'root=/dev/sda'
                        snapshot = ''
                    else:
                        driveif = 'virtio'
                        root = 'root=/dev/vda'
                        rrid = ''
                        snapshot = ',snapshot'
                    if self.env['baremetal'] is None:
                        if not os.path.exists(self.env['qcow2_file']):
                            if not os.path.exists(self.env['rootfs_raw_file']):
                                raise_rootfs_not_found()
                            self.raw_to_qcow2(qemu_which=self.env['qemu_which'])
                        extra_emulator_args.extend([
                            '-drive',
                            'file={},format=qcow2,if={}{}{}'.format(
                                self.env['disk_image'],
                                driveif,
                                snapshot,
                                rrid
                            ),
                            LF,
                        ])
                        if rr:
                            extra_emulator_args.extend([
                            '-drive', 'driver=blkreplay,if=none,image=img-direct,id=img-blkreplay', LF,
                            '-device', 'ide-hd,drive=img-blkreplay', LF,
                        ])
                if rr:
                    extra_emulator_args.extend([
                        '-object', 'filter-replay,id=replay,netdev=net0',
                        '-icount', 'shift=7,rr={},rrfile={}'.format(
                            'record' if self.env['record'] else 'replay',
                            self.env['qemu_rrfile']
                        ),
                    ])
                    virtio_gpu_pci = []
                else:
                    virtio_gpu_pci = ['-device', 'virtio-gpu-pci', LF]
                if self.env['arch'] == 'x86_64':
                    append = ['-append', '{} nopat {}'.format(root, kernel_cli), LF]
                    cmd.extend([
                        '-device', 'edu', LF,
                    ])
                elif self.env['is_arm']:
                    extra_emulator_args.extend(['-semihosting', LF])
                    append = ['-append', '{} {}'.format(root, kernel_cli), LF]
                    cmd.extend(
                        virtio_gpu_pci
                    )
                if self.env['baremetal'] is None:
                    cmd.extend(append)
            extra_emulator_args.extend([
                '-cpu', cpu, LF,
            ])
        if self.env['tmux']:
            tmux_args = '--run-id {}'.format(self.env['run_id'])
            if self.env['tmux_program'] == 'shell':
                if self.env['emulator'] == 'gem5':
                    tmux_cmd = os.path.join(self.env['root_dir'], 'gem5-shell')
                else:
                    raise Exception('--tmux-program is only supported in gem5 currently.')
            elif self.env['tmux_program'] == 'gdb':
                tmux_cmd = os.path.join(self.env['root_dir'], 'run-gdb')
                # TODO find a nicer way to forward all those args automatically.
                # Part of me wants to: https://github.com/jonathanslenders/pymux
                # but it cannot be used as a library properly it seems, and it is
                # slower than tmux.
                tmux_args += " --arch {} --emulator '{}' --gcc-which '{}' --linux-build-id '{}' --run-id '{}' --userland-build-id '{}'".format(
                    self.env['arch'],
                    self.env['emulator'],
                    self.env['gcc_which'],
                    self.env['linux_build_id'],
                    self.env['run_id'],
                    self.env['userland_build_id'],
                )
                if self.env['baremetal']:
                    tmux_args += " --baremetal '{}'".format(self.env['baremetal'])
                if self.env['userland']:
                    tmux_args += " --userland '{}'".format(self.env['userland'])
                if self.env['in_tree']:
                    tmux_args += ' --in-tree'
            if self.env['tmux_args'] is not None:
                tmux_args += ' {}'.format(self.env['tmux_args'])
            tmux_cmd = [
                os.path.join(self.env['root_dir'], 'tmux-split'),
                "sleep 2;{} {}".format(tmux_cmd, tmux_args)
            ]
            self.log_info(self.sh.cmd_to_string(tmux_cmd))
            subprocess.Popen(tmux_cmd)
        cmd.extend(extra_emulator_args)
        cmd.extend(self.env['extra_emulator_args'])
        if self.env['userland'] and self.env['emulator'] in ('qemu', 'native'):
            # The program and arguments must come at the every end of the CLI.
            cmd.extend([self.env['image'], LF])
            if self.env['userland_args'] is not None:
                cmd.extend(self.sh.shlex_split(self.env['userland_args']))
        if debug_vm or self.env['terminal']:
            out_file = None
        else:
            out_file = self.env['termout_file']
        exit_status = self.sh.run_cmd(
            cmd,
            cmd_file=self.env['run_cmd_file'],
            extra_env=extra_env,
            out_file=out_file,
            raise_on_failure=False,
            show_stdout=show_stdout,
        )
        if self.env['debug_vm_rr']:
            exit_status = self.sh.run_cmd(
                ['rr', 'replay', '-o', '-q'],
                raise_on_failure=False,
                show_stdout=show_stdout,
            )
        if exit_status == 0:
            error_string_found = False
            exit_status = 0
            if out_file is not None and not self.env['dry_run']:
                if self.env['emulator'] == 'gem5':
                    with open(self.env['termout_file'], 'br') as logfile:
                        # We have to do some parsing here because gem5 exits with status 0 even when panic happens.
                        # Grepping for '^panic: ' does not work because some errors don't show that message...
                        gem5_panic_re = re.compile(b'--- BEGIN LIBC BACKTRACE ---$')
                        line = None
                        for line in logfile:
                            line = line.rstrip()
                            if gem5_panic_re.search(line):
                                exit_status = 1
                        last_line = line
                        if last_line is not None:
                            if self.env['userland']:
                                match = re.search(b'Simulated exit code not 0! Exit code is (\d+)', last_line)
                                if match is not None:
                                    exit_status = int(match.group(1))
                            if re.search(b'Exiting @ tick \d+ because simulate\(\) limit reached', last_line) is not None:
                                exit_status = 1
                if not self.env['userland']:
                    if os.path.exists(self.env['guest_terminal_file']):
                        with open(self.env['guest_terminal_file'], 'br') as logfile:
                            linux_panic_re = re.compile(b'Kernel panic - not syncing')
                            serial_magic_exit_status_regexp = re.compile(self.env['serial_magic_exit_status_regexp_string'])
                            for line in logfile.readlines():
                                line = line.rstrip()
                                if not self.env['baremetal'] and linux_panic_re.search(line):
                                    exit_status = 1
                                match = serial_magic_exit_status_regexp.match(line)
                                if match:
                                    exit_status = int(match.group(1))
            if exit_status != 0 and self.env['show_stdout']:
                self.log_error('simulation error detected by parsing logs')
        return exit_status

if __name__ == '__main__':
    Main().cli()