Communication From xVM Hypervisor to Dom0 Using xm

Although the hypervisor and dom0 work closely together to manage a running system, the dom0 operating system has little direct visibility into the hypervisor. The hypervisor's entire address space is inaccessible to the dom0.

The only source of information is provided by the xm command, a user-space tool that communicates with the hypervisor via hypercalls.

Some of the commonly used xm commands are:

xm info

Report static information about the machine, such as number of CPUs, total memory, and xVM version.

# xm info host : test release : 5.11 version : onnv-userj machine : i86pc nr_cpus : 2 nr_nodes : 1 sockets_per_node : 2 cores_per_socket : 1 threads_per_core : 1 cpu_mhz : 2391 hw_caps : 078bfbff:e1d3fbff:00000000:00000010 total_memory : 4031 free_memory : 1953 xen_major : 3 xen_minor : 1 xen_extra : .2-xvm xen_caps : xen-3.0-x86_64 xen-3.0-x86_32p xen_scheduler : credit xen_pagesize : 4096 platform_params : virt_start=0xffff800000000000 xen_changeset : Thu Dec 20 20:11:49 2007 -0800 15623:41d827ccece7 cc_compiler : gcc version 3.4.3 (csl-sol210-3_4-20050802) cc_compile_by : userj cc_compile_domain : lab.sun.com cc_compile_date : Thu Dec 20 20:24:36 PST 2007 xend_config_format : 4

xm list

List all domains and some high-level information.

xm top

Analogous to the Linux top command, but it reports domain information instead of process information. Information about the xVM system and domains is displayed in a continuously updating manner through the xentop command. See xentop.

xm log

Display the contents of the xend log.

xm help

List all the available commands.

xentrace

Capture trace buffer data from xVM.

xentop

Display information about the xVM system and domains in a continuously updating manner. See xm top.

xm start domain

Start a managed domain that was created by virt-install.

If you modify guest domain CPUs or memory by using the xm command, these changes will be saved in the configuration file and persist across reboots.

See the xm(1M) man page for more information.