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How does the host machine communicate with the QEMU guest?
The host machine communicates with the QEMU guest agent through a VirtIO serial connection between the host and guest machines. A VirtIO serial channel is connected to the host via a character device driver (typically a Unix socket), and the guest listens on this serial channel.
How to setup QEMU output to console and automate using expect?
-serial pipe:/tmp/guest redirects a guest’s output to a /tmp/guest.out and allows to send input from host to guest via /tmp/guest.in. Wait until SSH Daemon starts. 4. Automate QEMU guest using expect tool
Why does QEMU redirect input to guest UART?
QEMU always redirects both input and output for a guest UART to the same place; this is true of all of ‘-serial stdio’, ‘-nographic’ (which does an implicit ‘-serial mon:stdio’) and ‘-serial pty’. So you don’t need to do anything extra. If UART input is not working then the problem seems likely to be a bug in your guest code.
Is the QEMU guest agent installed by default?
The QEMU guest agent package, qemu-guest-agent, is installed by default in Red Hat Enterprise Linux 7. This section covers the libvirt commands and options available to the guest agent. Note that it is only safe to rely on the QEMU guest agent when run by trusted guests.
What kind of network backend does QEMU use?
By default QEMU will create a SLiRP user network backend and an appropriate virtual network device for the guest (eg an E1000 PCI card for most x86 PC guests), as if you had typed -net nic -net user on your command line.
How to change guest DHCP allocation in QEMU?
Adding the following to the qemu command line will change the network configuration to use 192.168.76.0/24 instead of the default (10.0.2.0/24) and will start guest DHCP allocation from 9 (instead of 15): You can isolate the guest from the host (and broader network) using the restrict option.