QEMU is a versatile piece of software that has lots of different use cases. Here are some common configurations to (manually...) check.
Emulation mode:
- throw-away, user-mode/non-accelerated emulation
- KVM guest (incompatible with Xen)
- Xen HVM guest
User interfaces:
- virt-manager/libvirt
- gnome-boxes
ProxMox is Debian-based and would be a good test case, but they ship their own modified qemu version
Xen xl CLI
Guest systems:
- GNU/Linux
Windows: trial versions of Windows Server ISOs are easily available; pre-installed VMs are also available through modern.ie, with a conversion script; 2012R2 is known to crash with Xen HVM on first boot (Jessie)
Networking card:
- basic Ethernet emulation
- VirtIO networking (accelerated)
Networking attachment:
- slirp user-mode networking (NAT)
- bridge
- ...
Disk types:
- IDE, SCSI emulation (non-accelerated)
VirtIO disk (accelerated, may require drivers ISO)
iSCSI client/initiator (you can install tgt on a separate box for a test server/target, and qemu-block-extra)
Graphic access:
- SDL (direct window)
- VNC (e.g. with vncviewer)
- Spice (e.g. with virt-manager)
Common issues
Make sure you reserve enough memory (-m). For instance, Jessie's default is 128M but running the Stretch installer CD-ROM plain panics with that amount.
ASAN build
LTS/Development/Asan doesn't support static builds, so in addition to the DEB_*FLAGS_APPEND, drop qemu-user/qemu-user-static from debian/control and debian/control-in before building.