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<!DOCTYPE html>
<html dir="ltr" lang="en">
    <head>
        <meta charset='utf-8'>
        <title>Qemu</title>
    </head>
    <body>

        <a href="index.html">Tools Index</a>

        <h1>Qemu</h1>

        <h2 id="kern">1. Host System</h2>

        <p>Load modules, in this case kvm of intel cpu;</p>

        <pre>
        # modprobe -a kvm-intel tun virtio
        </pre>

        <p>Add users to kvm group;</p>

        <pre>
        # usermod -a -G kvm c9admin
        # usermod -a -G kvm username
        </pre>

        <h2 id="disk">2. Disk images</h2>

        <dl>
            <dt>img</dt>
            <dd>Raw disk image, allows dd to a physical device.</dd>
            <dt>raw</dt>
            <dd>Raw disk image, allows dd to a physical device.</dd>
            <dt>qcow2</dt>
            <dd>Qcow disk image file used by qemu.</dd>
        </dl>

        <p>Create hard disk image, there is different types,
        this describes how to create a qcow2 type;</p>

        <pre>
        $ qemu-img create -f qcow2 crux-img.qcow2 15G
        </pre>

        <p>You can mount disk image;</p>

        <pre>
        $ sudo modprobe nbd
        $ sudo qemu-nbd -c /dev/nbd0 /crux-img.qcow2
        </pre>

        <p>To disconnect image disk (ndb);</p>

        <pre>
        $ sudo qemu-nbd -d /dev/nbd0
        </pre>

        <p>Information about preparing
        <a href="../core/install.html#step2">partitions</a>
        and <a href="storage.html">storage</a> administration.
        You can use image as a normal disk, example how
        to use parted to create a gpt system table;</p>

        <pre>
        # parted /dev/nbd0
        (parted) mklabel gpt
        (parted) mkpart ext4 0% 100%
        (parted) set 1 boot on
        </pre>

        <pre>
        # kpartx -a -s -l -u /dev/nbd0
        </pre>

        <pre>
        # mkfs.ext4 /dev/mapper/nbd0p1
        </pre>

        <p>Mount partition;</p>

        <pre>
        # mount /dev/mapper/nbd0p1
        </pre>

        <h2 id="net">2. Network</h2>

        <p>Network configuration;</p>

        <dl>
            <dt>slirp</dt>
            <dd>Default virtual NAT'd network.</dd>
            <dt>tun/tap</dt>
            <dd>Good performance to create virtually any type of network
            topology.</dd>
            <dt>vde</dt>
            <dd>The VDE networking backend.</dd>
        </dl>

        <pre>
        KERNEL=="tun", GROUP="kvm", MODE="0660", OPTIONS+="static_node=net/tun"
        </pre>


        <h3>2.1. Public Bridge</h3>

        <p>Create <a href="network.html#bridge">bridge</a>, create new
        tap and add it to bridge;</p>

        <pre>
        # DEV="br0"
        # TAP="tap5"
        </pre>

        <pre>
        # ip tuntap add ${TAP} mode tap group kvm
        # ip link set ${TAP} up
        </pre>

        <pre>
        # ip link set ${TAP} master ${DEV}
        </pre>

        <p>See <a href="scripts/system-qemu.sh">scripts/system-qemu.sh</a>,
        as template. Run virtual machine that uses above tap device;</p>

        <pre>
        $ ISO=~/crux-3.2.iso
        $ IMG=~/crux-img.qcow2

        $ qemu-system-x86_64 \
            -enable-kvm \
            -m 1024 \
            -boot d \
            -cdrom ${ISO} \
            -hda ${IMG} \
            -net nic,model=virtio -net tap,ifname=${TAP},script=no,downscript=no
        </pre>

        <h3>2.2. Routing</h3>

        <p>Create interface with correct permissions set for kvm group.</p>

        <pre>
        # sysctl -w net.ipv4.ip_forward=1
        # iptables -t nat -A POSTROUTING -s 10.0.0.0/24 -o eth0 -j MASQUERADE
        </pre>

        <h2 id="guest">Guest System</h2>

        <p>Start qemu with 512 of ram, mydisk.img as disk and boot from iso</p>

        <pre>
        $ ISO=~/crux-3.2.iso
        $ IMG=~/crux-img.qcow2

        $ qemu-system-x86_64 \
            -enable-kvm \
            -m 1024 \
            -boot d \
            -cdrom ${ISO} \
            -hda ${IMG} \
            -net nic,model=virtio -net tap,ifname=${TAP},script=no,downscript=no
        </pre>

        <a href="index.html">Tools Index</a>
        <p>This is part of the c9 Manual.
        Copyright (C) 2016
        c9 team.
        See the file <a href="../fdl-1.3-standalone.html">Gnu Free Documentation License</a>
        for copying conditions.</p>
    </body>
</html>