system/i386/xen.rst

1 Xen HVM guest support
8 KVM has support for hosting Xen guests, intercepting Xen hypercalls and event
9 channel (Xen PV interrupt) delivery. This allows guests which expect to be
10 run under Xen to be hosted in QEMU under Linux/KVM instead.
12 Using the split irqchip is mandatory for Xen support.
17 Xen mode is enabled by setting the ``xen-version`` property of the KVM
18 accelerator, for example for Xen 4.17:
22   |qemu_system| --accel kvm,xen-version=0x40011,kernel-irqchip=split
25 ``xen-vapic`` CPU flag:
29   |qemu_system| --accel kvm,xen-version=0x40011,kernel-irqchip=split --cpu host,+xen-vapic
31 When Xen support is enabled, QEMU changes hypervisor identification (CPUID
32 0x40000000..0x4000000A) to Xen. The KVM identification and features are not
33 advertised to a Xen guest. If Hyper-V is also enabled, the Xen identification
41 ``xen-version``
42   This property contains the Xen version in ``XENVER_version`` form, with the
44   Setting this property enables the Xen guest support. If Xen version 4.5 or
45   greater is specified, the HVM leaf in Xen CPUID is populated. Xen version
49 ``xen-evtchn-max-pirq``
50   Xen PIRQs represent an emulated physical interrupt, either GSI or MSI, which
58 ``xen-gnttab-max-frames``
59   Xen grant tables are the means by which a Xen guest grants access to its
67 Xen paravirtual devices
70 The Xen PCI platform device is enabled automatically for a Xen guest. This
74 Those paravirtual Xen block, network (and console) devices can be created
77 To provide a Xen console device, define a character device and then a device
78 of type ``xen-console`` to connect to it. For the Xen console equivalent of
83    -device xen-console,chardev=char0
85 The Xen network device is ``xen-net-device``, which becomes the default NIC
86 model for emulated Xen guests, meaning that just the default NIC provided
87 by QEMU should automatically work and present a Xen network device to the
90 Disks can be configured with '``-drive file=${GUEST_IMAGE},if=xen``' and will
93 Under Xen, the boot disk is typically available both via IDE emulation, and
95 kernel, which then unplugs the IDE and continues with the Xen PV block device.
101   |qemu_system| --accel kvm,xen-version=0x40011,kernel-irqchip=split \\
102        -drive file=${GUEST_IMAGE},if=xen \\
108 Booting Xen PV guests
111 Booting PV guest kernels is possible by using the Xen PV shim (a version of Xen
112 itself, designed to run inside a Xen HVM guest and provide memory management
115 The Xen binary is provided as the ``-kernel`` and the guest kernel itself (or
121   |qemu_system| --accel kvm,xen-version=0x40011,kernel-irqchip=split \\
122        -chardev stdio,id=char0 -device xen-console,chardev=char0 \\
123        -display none  -m 1G  -kernel xen -initrd bzImage \\
124        -append "pv-shim console=xen,pv -- console=hvc0 root=/dev/xvda1" \\
125        -drive file=${GUEST_IMAGE},if=xen
127 The Xen image must be built with the ``CONFIG_XEN_GUEST`` and ``CONFIG_PV_SHIM``
128 options, and as of Xen 4.17, Xen's PV shim mode does not support using a serial
129 port; it must have a Xen console or it will panic.
132 (" ``--`` ") on the Xen command line, and does not provide the guest kernel
141 The minimal Xen support in the KVM accelerator requires the host to be running
143 acceleration of interrupt delivery via the Xen PIRQ mechanism, and Linux v5.19
144 accelerated Xen PV timers and inter-processor interrupts (IPIs).