The emulators/qemu port

qemu-8.2.2 – multi system emulator (cvsweb github mirror)

Description

QEMU is an open source machine emulator. It can run OSes and programs
made for one machine (e.g. an ARM board) on a different machine (e.g.
your own PC). By using dynamic translation, it achieves very good
performance.

WWW: https://www.qemu.org/

Readme

+-----------------------------------------------------------------------
| Running ${PKGSTEM} on OpenBSD
+-----------------------------------------------------------------------

==> Quick Start

1. Get a bootable CDROM image:

    $ ftp https://cdn.openbsd.org/pub/OpenBSD/snapshots/i386/cd74.iso

   or to use a 64-bit client OS or SPARC64, respectively:

    $ ftp https://cdn.openbsd.org/pub/OpenBSD/snapshots/amd64/cd74.iso

    $ ftp https://cdn.openbsd.org/pub/OpenBSD/snapshots/sparc64/cd74.iso

2. Create a virtual disk image:

    $ qemu-img create -f qcow2 virtual.img 10G

3. Install the OS:

    $ qemu-system-i386 -m 64 -monitor stdio -no-fd-bootchk \
	-hda virtual.img -cdrom cd74.iso -boot d

   or:

    $ qemu-system-x86_64 -m 64 -monitor stdio -no-fd-bootchk \
	-hda virtual.img -cdrom cd74.iso -boot d

    $ qemu-system-sparc64 -m 64 -monitor stdio \
	-hda virtual.img -cdrom cd74.iso -boot d \
        -net nic,model=ne2k_pci -net user

   NOTE: start this inside an xterm or equivalent.
   NOTE: be sure to choose serial console during install.
   NOTE: -no-fd-bootchk permits booting faster when no floppy is
         in use, but is not supported for qemu-system-sparc.
   NOTE: qemu-system-ppc* and qemu-system-sparc* currently fail with
         J or S malloc flags

4. Compress the virtual disk:

    $ qemu-img convert -c -O qcow2 virtual.img v.tmp && \
	mv v.tmp virtual.img

   NOTE: do not do this while QEMU is running / using this virtual
         disk.

5. Boot normally from the virtual disk:

    $ qemu-system-i386 -m 64 -nographic -no-fd-bootchk -hda virtual.img

   or:

    $ qemu-system-x86_64 -m 64 -nographic -no-fd-bootchk -hda virtual.img

    $ qemu-system-sparc64 -m 64 -nographic -hda virtual.img \
	-net nic,model=ne2k_pci -net user

==> Networking

1. Default Settings

   By default, QEMU sets up the equivalent of the following networking:

	-net nic,vlan=0,model=e1000,macaddr=52:54:00:12:34:56
	-net user,vlan=0

   Also, inside this virtual usermode network, it uses the 10.0.2.0/24
   and serves DHCP from inside this virtual network.  Static address
   can be used if one cannot or does not want to do DHCP in the
   guest OS:

	Guest OS IP     : 10.0.2.15
	Default Gateway : 10.0.2.2
	Nameserver      : 10.0.2.3

   It is sufficient for most operations, QEMU itself performs NAT
   and then makes userland network calls for TCP/UDP operations.
   ICMP and other things are not possible in this mode.

   NOTE: If you use one '-net' cmdline argument, QEMU assumes you
         know what you want and clears defaults for the rest of the
         -net defaults.

   NOTE: The guest mode networking does not currently support IPv6,
         and QEMU will complain that it cannot find a DNS server
         if /etc/resolv.conf contains only IPv6 DNS servers.

2. tap mode

   Sometimes it is desirable to configure QEMU to access a network
   via layer2 directly. One way of doing this without having to run
   QEMU as root is to let root open /dev/tapN and pass the file
   descriptor to QEMU. The tap(4) interface should preferrably be
   configured before starting QEMU:

    $ doas ifconfig tap0 192.168.0.254

   The interface can also be configured as part of a bridge(4), in
   which case the ip address can be omitted:

    $ doas ifconfig bridge0 add tap0 add em0 up

   The tunnel and bridge interfaces can also be configured at system
   startup by editing /etc/hostname.tapN and /etc/hostname.bridgeN,
   respectively (see hostname.if(5)).

   After configuring the virtual network we can use doas to let
   root open the tunnel device and then use doas again to drop
   privileges and start QEMU:

    $ doas sh -c "doas -u $USER qemu-system-i386 -nographic -net nic \
	-net tap,fd=3 -no-fd-bootchk -hda virtual.img 3<>/dev/tap0"

   NOTE: if you use sudo instead of doas, remember that sudo calls
         closefrom(2).  In order to have more than one fd passed tap
         interface, a line to sudoers akin to:

		Defaults closefrom_override

         then calling sudo via 'sudo -C 5 -u $USER qemu-system-i386 ..'
         is required.  See sudoers(5) and sudo(8) for details.

   An alternative to the procedure described above is to have QEMU
   set up the network via ${SYSCONFDIR}/qemu-ifup. This is not
   recommended however, since you would have to run QEMU as root,
   and there is no way to drop from root privileges at this point.

   ${SYSCONFDIR}/qemu-ifup contains some default settings that
   permit one to do the following:

    # qemu-system-i386 -net nic -net tap -no-fd-bootchk -hda virtual.img

   It presumes you wish the tap(4) interface to talk to the interface
   holding the default IPv4 route (falling back to trunk0 if no
   route is found), and that you want 'bridge0' to be used to bridge
   the two.

   Setting the environment variables ETHER and BRIDGE will override
   these settings, respectively.

   When starting QEMU, the script attempts to output useful
   information, but there are also error messages that occur as
   well.  On my laptop, I want to route / nat natively using PF and
   also have layer2 access to the QEMU networks.  I thus have this
   as /etc/hostname.trunk101:

	inet6 fe80::1c 64 lladdr 00:03:25:0d:7a:2c
	inet 10.7.255.1 255.255.255.0
	inet6 alias 2001:240:58a:45::1c

   I have dhcpd configured to run on trunk101, and also run rad.
   For QEMU, the startup looks like this:

    # export ETHER=trunk101
    # export BRIDGE=bridge101
    # qemu-system-i386 -net nic,vlan=0,macaddr=52:54:00:12:35:00 \
	-net tap,vlan=0 -vnc :0 -localtime -usb -usbdevice tablet \
	-m 256 -no-fd-bootchk -hda virtual.img -monitor stdio
    {tap0 (bridge101 <-> trunk101)ifconfig: bridge101: No such process
    ifconfig: bridge101: No such process
    }
    (qemu)

   The errors are normal and should be ignored.  One can verify the
   networking is properly configured by verifying the bridge
   interface:

    $ ifconfig bridge101
    bridge101: flags=41
	groups: bridge
	priority 32768 hellotime 2 fwddelay 15 maxage 20 holdcnt 6 proto rstp
	designated: id 00:00:00:00:00:00 priority 0
	tap0 flags=3
		port 16 ifpriority 0 ifcost 0
	trunk101 flags=3
		port 6 ifpriority 0 ifcost 0
	Addresses (max cache: 100, timeout: 240):

   NOTE: When running multiple QEMU sessions simultaneously on the
         same bridge, care must be taken because the network MAC
         address defaults to 52:54:00:12:34:56 for every QEMU
         instance.  To change this, observe the macaddr= syntax in
         the above example and choose a unique lladdr per QEMU nic.

==> Mice

   NOTE: Certain OS's work much better with the USB tablet device
         than the normal PS/2 mouse handling.  See the above example
         for usage.

==> Serial Console

   Installing OpenBSD via serial console is sometimes desirable.
   X may not be available, and so on.  There are two ways to
   accomplish this, both in effect the same solution:

    a. qemu-system-i386 -vnc :0 -serial stdio .. virtual.img \
         -cdrom install74.iso -boot d

	- this option permits you to use VNC from some system to
          connect to the QEMU instance and 'set tty com0' at the
          'boot>' prompt.
	- you may then disconnect VNC and use the terminal from
          which you started QEMU to do the install.

    b. qemu-system-i386 -nographic .. virtual.img -fda floppy74.fs -boot a

	- this maps both the serial port and the (qemu) monitor
          prompt to the terminal QEMU was started on.
	- to flip between them, Ctrl-a c; see the QEMU man page for
          other commands that work in -nographic mode.
	- preparation of the floppy image to force serial console
          mode is straightforward:

		vnconfig vnd0 floppy74.fs
		mount /dev/vnd0c /mnt
		mkdir /mnt/etc
		echo set tty com0 > /mnt/etc/boot.conf
		umount /mnt
		vnconfig -u vnd0

     .. be sure to choose 'yes' for setting com0 to be the serial
        console.

   NOTE: OpenBSD poweroff does work with QEMU, which actually causes
         QEMU itself to exit.  This is a good thing, as it is
         currently not possible to set what block device is booted
         from at runtime from QEMU.  So if you start an installation
         booting from a CD-ROM, you will always boot off a CD-ROM
         every time you reboot that QEMU session until you exit and
         start QEMU again booting off the virtual hard drive.

==> daemonized QEMU

   Sometimes you want QEMU to start as part of a system script.

   Adding to some of the above, the -daemonize option comes in
   handy, as well as the telnet: designator for -serial and monitor.
   This is a complete example that may be cut-and-pasted into
   rc.local:

    hddir=/var/vm
    USER=qemu
    if [ -x ${TRUEPREFIX}/bin/qemu ]; then
	echo -n 'Qemu: vmi386'
	(
            ifconfig bridge101 add trunk101 add tap0 up

            sh -c "doas -u $USER \
                ${TRUEPREFIX}/bin/qemu-system-i386 \
                -daemonize \
                -nographic \
                -net nic,vlan=0,macaddr=52:54:00:4e:62:8f \
                -net tap,vlan=0,fd=3 \
                -m 128 \
                -hda $hddir/virtual.img \
                -serial telnet:127.0.0.1:1080,server,nowait \
                -monitor telnet:127.0.0.1:1081,server,nowait \
                -no-fd-bootchk 3<>/dev/tap0"
	)
	echo "."
    fi

    NOTE: this presumes the user `qemu' exists, create it or set
          USER= to an existing user to use this example.