docs: create virt/vm

virt/vm.md

@@ -0,0 +1,63 @@
+---
+title: Machine definition
+description: Virtual machine hardware
+published: true
+date: 2025-06-01T17:37:29.262Z
+tags: 
+editor: markdown
+dateCreated: 2025-06-01T17:37:29.262Z
+---
+
+# Virtual machine hardware
+
+Libvirt uses XML files to define virtual machine hardware.
+
+In the context of libvirt, a virtual machine or guest system is called a domain. In turn, a domain type refers to the hypervisor used for running the virtual machine.
+
+The following command output the XML description of the domain called *phyllomeos*
+
+```
+virsh dumpxml phyllomeos
+```
+
+``` 
+<domain type='kvm'>
+  [...]
+</domain>
+```
+
+## Domain type
+
+At the moment, Phyllome OS focuses solely on hardware-assisted virtualization with [KVM and QEMU](https://www.libvirt.org/drvqemu.html). Therefore, the domain type KVM is the one used by default.
+
+``` 
+<domain type='kvm'>
+  [...]
+</domain>
+```
+
+Not all QEMU commands are supported by Libvirt. To [pass QEMU commands](https://www.libvirt.org/drvqemu.html#pass-through-of-arbitrary-qemu-commands
+), one need to use the following instead and add the QEMU command line at the end :
+
+```
+<domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
+	[...]
+  <qemu:commandline>
+    <qemu:arg value='-device'/>
+    <qemu:arg value='ipmi-bmc-sim,id=bmc0'/>
+    <qemu:arg value='-device'/>
+    <qemu:arg value='smbus-impi,bmc=bmc0'/>
+    <qemu:env name='QEMU_MODULE_DIR' value='/usr/lib64/qemu'/>
+  </qemu:commandline>
+</domain>
+```
+
+> If QEMU command lines are not immediately provided, it will automatically revert to simply `<domain type='kvm'>` upon writing changes to the domain
+{.is-info}
+
+Under QEMU, the said domain definition translates to: 
+
+```
+qemu-system-x86_64 -enable-kvm [...]
+```
+