libvirt

libvirt - core interfaces for the libvirt library

Provides the interfaces of the libvirt library to handle Xen domains from a process running in domain 0

Author(s): Daniel Veillard <veillard@redhat.com>

Synopsis

#define VIR_NODEINFO_MAXCPUS(nodeinfo);
#define LIBVIR_VERSION_NUMBER;
#define VIR_USE_CPU(cpumap, cpu);
#define VIR_CPU_MAPLEN(cpu);
#define VIR_UUID_BUFLEN;
#define VIR_CPU_USABLE(cpumaps, maplen, vcpu, cpu);
#define VIR_COPY_CPUMAP(cpumaps, maplen, vcpu, cpumap);
#define VIR_DOMAIN_SCHED_FIELD_LENGTH;
#define VIR_UUID_STRING_BUFLEN;
#define VIR_GET_CPUMAP(cpumaps, maplen, vcpu);
#define VIR_UNUSE_CPU(cpumap, cpu);
typedef struct _virDomainBlockStats virDomainBlockStatsStruct;
typedef enum virDomainMigrateFlags;
typedef struct _virNodeInfo virNodeInfo;
typedef struct _virNetwork virNetwork;
typedef virDomainBlockStatsStruct * virDomainBlockStatsPtr;
typedef struct _virConnect virConnect;
typedef struct _virVcpuInfo virVcpuInfo;
typedef struct _virDomainInfo virDomainInfo;
typedef struct _virDomainInterfaceStats virDomainInterfaceStatsStruct;
typedef enum virDomainState;
typedef struct _virDomain virDomain;
typedef virDomainInterfaceStatsStruct * virDomainInterfaceStatsPtr;
typedef virConnectAuth * virConnectAuthPtr;
typedef enum virSchedParameterType;
typedef virConnectCredential * virConnectCredentialPtr;
typedef virNodeInfo * virNodeInfoPtr;
typedef virNetwork * virNetworkPtr;
typedef virDomainInfo * virDomainInfoPtr;
typedef virConnect * virConnectPtr;
typedef struct _virSchedParameter virSchedParameter;
typedef enum virConnectFlags;
typedef virSchedParameter * virSchedParameterPtr;
typedef enum virVcpuState;
typedef struct _virConnectAuth virConnectAuth;
typedef struct _virConnectCredential virConnectCredential;
typedef virVcpuInfo * virVcpuInfoPtr;
typedef enum virDomainXMLFlags;
typedef virDomain * virDomainPtr;
typedef enum virConnectCredentialType;
typedef enum virDomainCreateFlags;
int	virDomainGetInfo		(virDomainPtr domain, 
virDomainInfoPtr info); int virNetworkCreate (virNetworkPtr network); int virNetworkFree (virNetworkPtr network); const char * virNetworkGetName (virNetworkPtr network); const char * virDomainGetName (virDomainPtr domain); int virNetworkGetAutostart (virNetworkPtr network,
int * autostart); virDomainPtr virDomainDefineXML (virConnectPtr conn,
const char * xml); int virDomainShutdown (virDomainPtr domain); int virNetworkUndefine (virNetworkPtr network); int virGetVersion (unsigned long * libVer,
const char * type,
unsigned long * typeVer); int virConnectListDefinedDomains (virConnectPtr conn,
char ** const names,
int maxnames); char * virConnectGetCapabilities (virConnectPtr conn); int virInitialize (void); virDomainPtr virDomainLookupByName (virConnectPtr conn,
const char * name); virNetworkPtr virNetworkLookupByUUID (virConnectPtr conn,
const unsigned char * uuid); char * virNetworkGetBridgeName (virNetworkPtr network); int virDomainPinVcpu (virDomainPtr domain,
unsigned int vcpu,
unsigned char * cpumap,
int maplen); int virDomainRestore (virConnectPtr conn,
const char * from); const char * virConnectGetType (virConnectPtr conn); virNetworkPtr virNetworkLookupByName (virConnectPtr conn,
const char * name); unsigned long long virNodeGetFreeMemory (virConnectPtr conn); int virDomainGetSchedulerParameters (virDomainPtr domain,
virSchedParameterPtr params,
int * nparams); int virDomainCreate (virDomainPtr domain); int virConnectListDomains (virConnectPtr conn,
int * ids,
int maxids); virNetworkPtr virNetworkLookupByUUIDString (virConnectPtr conn,
const char * uuidstr); int virDomainCoreDump (virDomainPtr domain,
const char * to,
int flags); virDomainPtr virDomainLookupByUUID (virConnectPtr conn,
const unsigned char * uuid); virDomainPtr virDomainLookupByUUIDString (virConnectPtr conn,
const char * uuidstr); int virConnectNumOfDefinedNetworks (virConnectPtr conn); int virDomainUndefine (virDomainPtr domain); char * virDomainGetOSType (virDomainPtr domain); int virConnectListDefinedNetworks (virConnectPtr conn,
char ** const names,
int maxnames); int virNodeGetInfo (virConnectPtr conn,
virNodeInfoPtr info); int virDomainGetUUID (virDomainPtr domain,
unsigned char * uuid); int virDomainSetMemory (virDomainPtr domain,
unsigned long memory); int virNetworkSetAutostart (virNetworkPtr network,
int autostart); int virConnectNumOfDomains (virConnectPtr conn); int virDomainGetUUIDString (virDomainPtr domain,
char * buf); virConnectPtr virDomainGetConnect (virDomainPtr dom); unsigned long virDomainGetMaxMemory (virDomainPtr domain); int virDomainAttachDevice (virDomainPtr domain,
const char * xml); int virDomainGetMaxVcpus (virDomainPtr domain); int virDomainFree (virDomainPtr domain); virConnectPtr virConnectOpen (const char * name); int virDomainSetAutostart (virDomainPtr domain,
int autostart); int virDomainSuspend (virDomainPtr domain); int virConnectGetMaxVcpus (virConnectPtr conn,
const char * type); virConnectPtr virNetworkGetConnect (virNetworkPtr net); int virConnectNumOfDefinedDomains (virConnectPtr conn); virNetworkPtr virNetworkCreateXML (virConnectPtr conn,
const char * xmlDesc); virNetworkPtr virNetworkDefineXML (virConnectPtr conn,
const char * xml); virDomainPtr virDomainLookupByID (virConnectPtr conn,
int id); int virDomainSetSchedulerParameters (virDomainPtr domain,
virSchedParameterPtr params,
int nparams); int virNodeGetCellsFreeMemory (virConnectPtr conn,
unsigned long long * freeMems,
int startCell,
int maxCells); int virConnectClose (virConnectPtr conn); int virDomainReboot (virDomainPtr domain,
unsigned int flags); int virDomainBlockStats (virDomainPtr dom,
const char * path,
virDomainBlockStatsPtr stats,
size_t size); int virDomainSetVcpus (virDomainPtr domain,
unsigned int nvcpus); virConnectPtr virConnectOpenAuth (const char * name,
virConnectAuthPtr auth,
int flags); int virNetworkGetUUIDString (virNetworkPtr network,
char * buf); virDomainPtr virDomainMigrate (virDomainPtr domain,
virConnectPtr dconn,
unsigned long flags,
const char * dname,
const char * uri,
unsigned long bandwidth); char * virNetworkGetXMLDesc (virNetworkPtr network,
int flags); unsigned int virDomainGetID (virDomainPtr domain); int virDomainResume (virDomainPtr domain); virDomainPtr virDomainCreateLinux (virConnectPtr conn,
const char * xmlDesc,
unsigned int flags); char * virDomainGetSchedulerType (virDomainPtr domain,
int * nparams); int virNetworkDestroy (virNetworkPtr network); int virDomainDestroy (virDomainPtr domain); int virConnectNumOfNetworks (virConnectPtr conn); int virDomainDetachDevice (virDomainPtr domain,
const char * xml); int virDomainGetAutostart (virDomainPtr domain,
int * autostart); int virDomainGetVcpus (virDomainPtr domain,
virVcpuInfoPtr info,
int maxinfo,
unsigned char * cpumaps,
int maplen); int virNetworkGetUUID (virNetworkPtr network,
unsigned char * uuid); char * virConnectGetHostname (virConnectPtr conn); char * virDomainGetXMLDesc (virDomainPtr domain,
int flags); int virDomainSetMaxMemory (virDomainPtr domain,
unsigned long memory); int virDomainInterfaceStats (virDomainPtr dom,
const char * path,
virDomainInterfaceStatsPtr stats,
size_t size); typedef int virConnectAuthCallbackPtr (virConnectCredentialPtr cred,
unsigned int ncred,
void * cbdata); int virConnectGetVersion (virConnectPtr conn,
unsigned long * hvVer); int virConnectListNetworks (virConnectPtr conn,
char ** const names,
int maxnames); char * virConnectGetURI (virConnectPtr conn); int virDomainSave (virDomainPtr domain,
const char * to); virConnectPtr virConnectOpenReadOnly (const char * name);

Description

Details

Macro LIBVIR_VERSION_NUMBER

#define LIBVIR_VERSION_NUMBER;

Macro providing the version of the library as version * 1,000,000 + minor * 1000 + micro


Macro VIR_COPY_CPUMAP

#define VIR_COPY_CPUMAP(cpumaps, maplen, vcpu, cpumap);

This macro is to be used in conjonction with virDomainGetVcpus() and virDomainPinVcpu() APIs. VIR_COPY_CPUMAP macro extract the cpumap of the specified vcpu from cpumaps array and copy it into cpumap to be used later by virDomainPinVcpu() API.

cpumaps:pointer to an array of cpumap (in 8-bit bytes) (IN)
maplen:the length (in bytes) of one cpumap
vcpu:the virtual CPU number
cpumap:pointer to a cpumap (in 8-bit bytes) (OUT) This cpumap must be previously allocated by the caller (ie: malloc(maplen))

Macro VIR_CPU_MAPLEN

#define VIR_CPU_MAPLEN(cpu);

This macro is to be used in conjonction with virDomainPinVcpu() API. It returns the length (in bytes) required to store the complete CPU map between a single virtual & all physical CPUs of a domain.

cpu:number of physical CPUs

Macro VIR_CPU_USABLE

#define VIR_CPU_USABLE(cpumaps, maplen, vcpu, cpu);

This macro is to be used in conjonction with virDomainGetVcpus() API. VIR_CPU_USABLE macro returns a non zero value (true) if the cpu is usable by the vcpu, and 0 otherwise.

cpumaps:pointer to an array of cpumap (in 8-bit bytes) (IN)
maplen:the length (in bytes) of one cpumap
vcpu:the virtual CPU number
cpu:the physical CPU number

Macro VIR_DOMAIN_SCHED_FIELD_LENGTH

#define VIR_DOMAIN_SCHED_FIELD_LENGTH;

Macro providing the field length of virSchedParameter


Macro VIR_GET_CPUMAP

#define VIR_GET_CPUMAP(cpumaps, maplen, vcpu);

This macro is to be used in conjonction with virDomainGetVcpus() and virDomainPinVcpu() APIs. VIR_GET_CPUMAP macro returns a pointer to the cpumap of the specified vcpu from cpumaps array.

cpumaps:pointer to an array of cpumap (in 8-bit bytes) (IN)
maplen:the length (in bytes) of one cpumap
vcpu:the virtual CPU number

Macro VIR_NODEINFO_MAXCPUS

#define VIR_NODEINFO_MAXCPUS(nodeinfo);

This macro is to calculate the total number of CPUs supported but not neccessarily active in the host.

nodeinfo:virNodeInfo instance

Macro VIR_UNUSE_CPU

#define VIR_UNUSE_CPU(cpumap, cpu);

This macro is to be used in conjonction with virDomainPinVcpu() API. USE_CPU macro reset the bit (CPU not usable) of the related cpu in cpumap.

cpumap:pointer to a bit map of real CPUs (in 8-bit bytes) (IN/OUT)
cpu:the physical CPU number

Macro VIR_USE_CPU

#define VIR_USE_CPU(cpumap, cpu);

This macro is to be used in conjonction with virDomainPinVcpu() API. USE_CPU macro set the bit (CPU usable) of the related cpu in cpumap.

cpumap:pointer to a bit map of real CPUs (in 8-bit bytes) (IN/OUT)
cpu:the physical CPU number

Macro VIR_UUID_BUFLEN

#define VIR_UUID_BUFLEN;

This macro provides the length of the buffer required for virDomainGetUUID()


Macro VIR_UUID_STRING_BUFLEN

#define VIR_UUID_STRING_BUFLEN;

This macro provides the length of the buffer required for virDomainGetUUIDString()


Structure virConnect

struct _virConnect {
The content of this structure is not made public by the API.
} virConnect;


Structure virConnectAuth

struct _virConnectAuth {
    int *	credtype	: List of supported virConnectCredentialType values
    unsigned int	ncredtype
    virConnectAuthCallbackPtr	cb	: Callback used to collect credentials
    void *	cbdata
} virConnectAuth;


Typedef virConnectAuthPtr

virConnectAuth * virConnectAuthPtr;


Structure virConnectCredential

struct _virConnectCredential {
    int	type	: One of virConnectCredentialType constants
    const char *	prompt	: Prompt to show to user
    const char *	challenge	: Additional challenge to show
    const char *	defresult	: Optional default result
    char *	result	: Result to be filled with user response (or defresult)
    unsigned int	resultlen	: Length of the result
} virConnectCredential;


Typedef virConnectCredentialPtr

virConnectCredential * virConnectCredentialPtr;


Enum virConnectCredentialType

enum virConnectCredentialType {
    VIR_CRED_USERNAME = 1 /* Identity to act as */
    VIR_CRED_AUTHNAME = 2 /* Identify to authorize as */
    VIR_CRED_LANGUAGE = 3 /* RFC 1766 languages, comma separated */
    VIR_CRED_CNONCE = 4 /* client supplies a nonce */
    VIR_CRED_PASSPHRASE = 5 /* Passphrase secret */
    VIR_CRED_ECHOPROMPT = 6 /* Challenge response */
    VIR_CRED_NOECHOPROMPT = 7 /* Challenge response */
    VIR_CRED_REALM = 8 /* Authentication realm */
    VIR_CRED_EXTERNAL = 9 /*  Externally managed credential More may be added - expect the unexpected */
};


Enum virConnectFlags

enum virConnectFlags {
    VIR_CONNECT_RO = 1 /*  A readonly connection */
};


Typedef virConnectPtr

virConnect * virConnectPtr;

a virConnectPtr is pointer to a virConnect private structure, this is the type used to reference a connection to the Xen Hypervisor in the API.


Structure virDomain

struct _virDomain {
The content of this structure is not made public by the API.
} virDomain;


Typedef virDomainBlockStatsPtr

virDomainBlockStatsStruct * virDomainBlockStatsPtr;

A pointer to a virDomainBlockStats structure


Structure virDomainBlockStatsStruct

struct _virDomainBlockStats {
    long long	rd_req
    long long	rd_bytes
    long long	wr_req
    long long	wr_bytes
    long long	errs	: In Xen this returns the mysterious 'oo_req'.
} virDomainBlockStatsStruct;


Enum virDomainCreateFlags

enum virDomainCreateFlags {
    VIR_DOMAIN_NONE = 0
};


Structure virDomainInfo

struct _virDomainInfo {
    unsigned char	state	: the running state, one of virDomainFlags
    unsigned long	maxMem	: the maximum memory in KBytes allowed
    unsigned long	memory	: the memory in KBytes used by the domain
    unsigned short	nrVirtCpu	: the number of virtual CPUs for the domain
    unsigned long long	cpuTime	: the CPU time used in nanoseconds
} virDomainInfo;


Typedef virDomainInfoPtr

virDomainInfo * virDomainInfoPtr;

a virDomainInfoPtr is a pointer to a virDomainInfo structure.


Typedef virDomainInterfaceStatsPtr

virDomainInterfaceStatsStruct * virDomainInterfaceStatsPtr;

A pointe to a virDomainInterfaceStats structure


Structure virDomainInterfaceStatsStruct

struct _virDomainInterfaceStats {
    long long	rx_bytes
    long long	rx_packets
    long long	rx_errs
    long long	rx_drop
    long long	tx_bytes
    long long	tx_packets
    long long	tx_errs
    long long	tx_drop
} virDomainInterfaceStatsStruct;


Enum virDomainMigrateFlags

enum virDomainMigrateFlags {
    VIR_MIGRATE_LIVE = 1 /*  live migration */
};


Typedef virDomainPtr

virDomain * virDomainPtr;

a virDomainPtr is pointer to a virDomain private structure, this is the type used to reference a Xen domain in the API.


Enum virDomainState

enum virDomainState {
    VIR_DOMAIN_NOSTATE = 0 /* no state */
    VIR_DOMAIN_RUNNING = 1 /* the domain is running */
    VIR_DOMAIN_BLOCKED = 2 /* the domain is blocked on resource */
    VIR_DOMAIN_PAUSED = 3 /* the domain is paused by user */
    VIR_DOMAIN_SHUTDOWN = 4 /* the domain is being shut down */
    VIR_DOMAIN_SHUTOFF = 5 /* the domain is shut off */
    VIR_DOMAIN_CRASHED = 6 /*  the domain is crashed */
};


Enum virDomainXMLFlags

enum virDomainXMLFlags {
    VIR_DOMAIN_XML_SECURE = 1 /* dump security sensitive informations too */
    VIR_DOMAIN_XML_INACTIVE = 2 /*  dump inactive domain informations */
};


Structure virNetwork

struct _virNetwork {
The content of this structure is not made public by the API.
} virNetwork;


Typedef virNetworkPtr

virNetwork * virNetworkPtr;

a virNetworkPtr is pointer to a virNetwork private structure, this is the type used to reference a virtual network in the API.


Structure virNodeInfo

struct _virNodeInfo {
    charmodel[32]	model	: string indicating the CPU model
    unsigned long	memory	: memory size in kilobytes
    unsigned int	cpus	: the number of active CPUs
    unsigned int	mhz	: expected CPU frequency
    unsigned int	nodes	: the number of NUMA cell, 1 for uniform mem access
    unsigned int	sockets	: number of CPU socket per node
    unsigned int	cores	: number of core per socket
    unsigned int	threads	: number of threads per core
} virNodeInfo;


Typedef virNodeInfoPtr

virNodeInfo * virNodeInfoPtr;

a virNodeInfoPtr is a pointer to a virNodeInfo structure.


Structure virSchedParameter

struct _virSchedParameter {
    charfield[VIR_DOMAIN_SCHED_FIELD_LENGTH]	field	: parameter name
    int	type	: parameter type
} virSchedParameter;


Typedef virSchedParameterPtr

virSchedParameter * virSchedParameterPtr;

a virSchedParameterPtr is a pointer to a virSchedParameter structure.


Enum virSchedParameterType

enum virSchedParameterType {
    VIR_DOMAIN_SCHED_FIELD_INT = 1 /* integer case */
    VIR_DOMAIN_SCHED_FIELD_UINT = 2 /* unsigned integer case */
    VIR_DOMAIN_SCHED_FIELD_LLONG = 3 /* long long case */
    VIR_DOMAIN_SCHED_FIELD_ULLONG = 4 /* unsigned long long case */
    VIR_DOMAIN_SCHED_FIELD_DOUBLE = 5 /* double case */
    VIR_DOMAIN_SCHED_FIELD_BOOLEAN = 6 /*  boolean(character) case */
};


Structure virVcpuInfo

struct _virVcpuInfo {
    unsigned int	number	: virtual CPU number
    int	state	: value from virVcpuState
    unsigned long long	cpuTime	: CPU time used, in nanoseconds
    int	cpu	: real CPU number, or -1 if offline
} virVcpuInfo;


Typedef virVcpuInfoPtr

virVcpuInfo * virVcpuInfoPtr;


Enum virVcpuState

enum virVcpuState {
    VIR_VCPU_OFFLINE = 0 /* the virtual CPU is offline */
    VIR_VCPU_RUNNING = 1 /* the virtual CPU is running */
    VIR_VCPU_BLOCKED = 2 /*  the virtual CPU is blocked on resource */
};


Function type virConnectAuthCallbackPtr

int	virConnectAuthCallbackPtr	(virConnectCredentialPtr cred, 
unsigned int ncred,
void * cbdata)

cred:
ncred:
cbdata:
Returns:

Variable virConnectAuthPtrDefault

virConnectAuthPtr virConnectAuthPtrDefault;


virConnectClose ()

int	virConnectClose			(virConnectPtr conn)

This function closes the connection to the Hypervisor. This should not be called if further interaction with the Hypervisor are needed especially if there is running domain which need further monitoring by the application.

conn:pointer to the hypervisor connection
Returns:0 in case of success or -1 in case of error.

virConnectGetCapabilities ()

char *	virConnectGetCapabilities	(virConnectPtr conn)

Provides capabilities of the hypervisor / driver.

conn:pointer to the hypervisor connection
Returns:NULL in case of error, or an XML string defining the capabilities. The client must free the returned string after use.

virConnectGetHostname ()

char *	virConnectGetHostname		(virConnectPtr conn)

This returns the system hostname on which the hypervisor is running (the result of the gethostname(2) system call). If we are connected to a remote system, then this returns the hostname of the remote system.

conn:pointer to a hypervisor connection
Returns:the hostname which must be freed by the caller, or NULL if there was an error.

virConnectGetMaxVcpus ()

int	virConnectGetMaxVcpus		(virConnectPtr conn, 
const char * type)

Provides the maximum number of virtual CPUs supported for a guest VM of a specific type. The 'type' parameter here corresponds to the 'type' attribute in the <domain> element of the XML.

conn:pointer to the hypervisor connection
type:value of the 'type' attribute in the <domain> element
Returns:the maximum of virtual CPU or -1 in case of error.

virConnectGetType ()

const char *	virConnectGetType	(virConnectPtr conn)

Get the name of the Hypervisor software used.

conn:pointer to the hypervisor connection
Returns:NULL in case of error, a static zero terminated string otherwise. See also: http://www.redhat.com/archives/libvir-list/2007-February/msg00096.html

virConnectGetURI ()

char *	virConnectGetURI		(virConnectPtr conn)

This returns the URI (name) of the hypervisor connection. Normally this is the same as or similar to the string passed to the virConnectOpen/virConnectOpenReadOnly call, but the driver may make the URI canonical. If name == NULL was passed to virConnectOpen, then the driver will return a non-NULL URI which can be used to connect to the same hypervisor later.

conn:pointer to a hypervisor connection
Returns:the URI string which must be freed by the caller, or NULL if there was an error.

virConnectGetVersion ()

int	virConnectGetVersion		(virConnectPtr conn, 
unsigned long * hvVer)

Get the version level of the Hypervisor running. This may work only with hypervisor call, i.e. with priviledged access to the hypervisor, not with a Read-Only connection.

conn:pointer to the hypervisor connection
hvVer:return value for the version of the running hypervisor (OUT)
Returns:-1 in case of error, 0 otherwise. if the version can't be extracted by lack of capacities returns 0 and @hvVer is 0, otherwise @hvVer value is major * 1,000,000 + minor * 1,000 + release

virConnectListDefinedDomains ()

int	virConnectListDefinedDomains	(virConnectPtr conn, 
char ** const names,
int maxnames)

list the defined domains, stores the pointers to the names in @names

conn:pointer to the hypervisor connection
names:pointer to an array to store the names
maxnames:size of the array
Returns:the number of names provided in the array or -1 in case of error

virConnectListDefinedNetworks ()

int	virConnectListDefinedNetworks	(virConnectPtr conn, 
char ** const names,
int maxnames)

list the inactive networks, stores the pointers to the names in @names

conn:pointer to the hypervisor connection
names:pointer to an array to store the names
maxnames:size of the array
Returns:the number of names provided in the array or -1 in case of error

virConnectListDomains ()

int	virConnectListDomains		(virConnectPtr conn, 
int * ids,
int maxids)

Collect the list of active domains, and store their ID in @maxids

conn:pointer to the hypervisor connection
ids:array to collect the list of IDs of active domains
maxids:size of @ids
Returns:the number of domain found or -1 in case of error

virConnectListNetworks ()

int	virConnectListNetworks		(virConnectPtr conn, 
char ** const names,
int maxnames)

Collect the list of active networks, and store their names in @names

conn:pointer to the hypervisor connection
names:array to collect the list of names of active networks
maxnames:size of @names
Returns:the number of networks found or -1 in case of error

virConnectNumOfDefinedDomains ()

int	virConnectNumOfDefinedDomains	(virConnectPtr conn)

Provides the number of inactive domains.

conn:pointer to the hypervisor connection
Returns:the number of domain found or -1 in case of error

virConnectNumOfDefinedNetworks ()

int	virConnectNumOfDefinedNetworks	(virConnectPtr conn)

Provides the number of inactive networks.

conn:pointer to the hypervisor connection
Returns:the number of networks found or -1 in case of error

virConnectNumOfDomains ()

int	virConnectNumOfDomains		(virConnectPtr conn)

Provides the number of active domains.

conn:pointer to the hypervisor connection
Returns:the number of domain found or -1 in case of error

virConnectNumOfNetworks ()

int	virConnectNumOfNetworks		(virConnectPtr conn)

Provides the number of active networks.

conn:pointer to the hypervisor connection
Returns:the number of network found or -1 in case of error

virConnectOpen ()

virConnectPtr	virConnectOpen		(const char * name)

This function should be called first to get a connection to the Hypervisor and xen store

name:URI of the hypervisor
Returns:a pointer to the hypervisor connection or NULL in case of error URIs are documented at http://libvirt.org/uri.html

virConnectOpenAuth ()

virConnectPtr	virConnectOpenAuth	(const char * name, 
virConnectAuthPtr auth,
int flags)

This function should be called first to get a connection to the Hypervisor. If neccessary, authentication will be performed fetching credentials via the callback

name:URI of the hypervisor
auth:Authenticate callback parameters
flags:Open flags
Returns:a pointer to the hypervisor connection or NULL in case of error URIs are documented at http://libvirt.org/uri.html

virConnectOpenReadOnly ()

virConnectPtr	virConnectOpenReadOnly	(const char * name)

This function should be called first to get a restricted connection to the libbrary functionalities. The set of APIs usable are then restricted on the available methods to control the domains.

name:URI of the hypervisor
Returns:a pointer to the hypervisor connection or NULL in case of error URIs are documented at http://libvirt.org/uri.html

virDomainAttachDevice ()

int	virDomainAttachDevice		(virDomainPtr domain, 
const char * xml)

Create a virtual device attachment to backend.

domain:pointer to domain object
xml:pointer to XML description of one device
Returns:0 in case of success, -1 in case of failure.

virDomainBlockStats ()

int	virDomainBlockStats		(virDomainPtr dom, 
const char * path,
virDomainBlockStatsPtr stats,
size_t size)

This function returns block device (disk) stats for block devices attached to the domain. The path parameter is the name of the block device. Get this by calling virDomainGetXMLDesc and finding the <target dev='...'> attribute within //domain/devices/disk. (For example, "xvda"). Domains may have more than one block device. To get stats for each you should make multiple calls to this function. Individual fields within the stats structure may be returned as -1, which indicates that the hypervisor does not support that particular statistic.

dom:pointer to the domain object
path:path to the block device
stats:block device stats (returned)
size:size of stats structure
Returns:0 in case of success or -1 in case of failure.

virDomainCoreDump ()

int	virDomainCoreDump		(virDomainPtr domain, 
const char * to,
int flags)

This method will dump the core of a domain on a given file for analysis. Note that for remote Xen Daemon the file path will be interpreted in the remote host.

domain:a domain object
to:path for the core file
flags:extra flags, currently unused
Returns:0 in case of success and -1 in case of failure.

virDomainCreate ()

int	virDomainCreate			(virDomainPtr domain)

launch a defined domain. If the call succeed the domain moves from the defined to the running domains pools.

domain:pointer to a defined domain
Returns:0 in case of success, -1 in case of error

virDomainCreateLinux ()

virDomainPtr	virDomainCreateLinux	(virConnectPtr conn, 
const char * xmlDesc,
unsigned int flags)

Launch a new Linux guest domain, based on an XML description similar to the one returned by virDomainGetXMLDesc() This function may requires priviledged access to the hypervisor.

conn:pointer to the hypervisor connection
xmlDesc:an XML description of the domain
flags:an optional set of virDomainFlags
Returns:a new domain object or NULL in case of failure

virDomainDefineXML ()

virDomainPtr	virDomainDefineXML	(virConnectPtr conn, 
const char * xml)

define a domain, but does not start it

conn:pointer to the hypervisor connection
xml:the XML description for the domain, preferably in UTF-8
Returns:NULL in case of error, a pointer to the domain otherwise

virDomainDestroy ()

int	virDomainDestroy		(virDomainPtr domain)

Destroy the domain object. The running instance is shutdown if not down already and all resources used by it are given back to the hypervisor. The data structure is freed and should not be used thereafter if the call does not return an error. This function may requires priviledged access

domain:a domain object
Returns:0 in case of success and -1 in case of failure.

virDomainDetachDevice ()

int	virDomainDetachDevice		(virDomainPtr domain, 
const char * xml)

Destroy a virtual device attachment to backend.

domain:pointer to domain object
xml:pointer to XML description of one device
Returns:0 in case of success, -1 in case of failure.

virDomainFree ()

int	virDomainFree			(virDomainPtr domain)

Free the domain object. The running instance is kept alive. The data structure is freed and should not be used thereafter.

domain:a domain object
Returns:0 in case of success and -1 in case of failure.

virDomainGetAutostart ()

int	virDomainGetAutostart		(virDomainPtr domain, 
int * autostart)

Provides a boolean value indicating whether the domain configured to be automatically started when the host machine boots.

domain:a domain object
autostart:the value returned
Returns:-1 in case of error, 0 in case of success

virDomainGetConnect ()

virConnectPtr	virDomainGetConnect	(virDomainPtr dom)

Provides the connection pointer associated with a domain. The reference counter on the connection is not increased by this call. WARNING: When writing libvirt bindings in other languages, do not use this function. Instead, store the connection and the domain object together.

dom:pointer to a domain
Returns:the virConnectPtr or NULL in case of failure.

virDomainGetID ()

unsigned int	virDomainGetID		(virDomainPtr domain)

Get the hypervisor ID number for the domain

domain:a domain object
Returns:the domain ID number or (unsigned int) -1 in case of error

virDomainGetInfo ()

int	virDomainGetInfo		(virDomainPtr domain, 
virDomainInfoPtr info)

Extract information about a domain. Note that if the connection used to get the domain is limited only a partial set of the information can be extracted.

domain:a domain object
info:pointer to a virDomainInfo structure allocated by the user
Returns:0 in case of success and -1 in case of failure.

virDomainGetMaxMemory ()

unsigned long	virDomainGetMaxMemory	(virDomainPtr domain)

Retrieve the maximum amount of physical memory allocated to a domain. If domain is NULL, then this get the amount of memory reserved to Domain0 i.e. the domain where the application runs.

domain:a domain object or NULL
Returns:the memory size in kilobytes or 0 in case of error.

virDomainGetMaxVcpus ()

int	virDomainGetMaxVcpus		(virDomainPtr domain)

Provides the maximum number of virtual CPUs supported for the guest VM. If the guest is inactive, this is basically the same as virConnectGetMaxVcpus. If the guest is running this will reflect the maximum number of virtual CPUs the guest was booted with.

domain:pointer to domain object
Returns:the maximum of virtual CPU or -1 in case of error.

virDomainGetName ()

const char *	virDomainGetName	(virDomainPtr domain)

Get the public name for that domain

domain:a domain object
Returns:a pointer to the name or NULL, the string need not be deallocated its lifetime will be the same as the domain object.

virDomainGetOSType ()

char *	virDomainGetOSType		(virDomainPtr domain)

Get the type of domain operation system.

domain:a domain object
Returns:the new string or NULL in case of error, the string must be freed by the caller.

virDomainGetSchedulerParameters ()

int	virDomainGetSchedulerParameters	(virDomainPtr domain, 
virSchedParameterPtr params,
int * nparams)

Get the scheduler parameters, the @params array will be filled with the values.

domain:pointer to domain object
params:pointer to scheduler parameter object (return value)
nparams:pointer to number of scheduler parameter (this value should be same than the returned value nparams of virDomainGetSchedulerType)
Returns:-1 in case of error, 0 in case of success.

virDomainGetSchedulerType ()

char *	virDomainGetSchedulerType	(virDomainPtr domain, 
int * nparams)

Get the scheduler type.

domain:pointer to domain object
nparams:number of scheduler parameters(return value)
Returns:NULL in case of error. The caller must free the returned string.

virDomainGetUUID ()

int	virDomainGetUUID		(virDomainPtr domain, 
unsigned char * uuid)

Get the UUID for a domain

domain:a domain object
uuid:pointer to a VIR_UUID_BUFLEN bytes array
Returns:-1 in case of error, 0 in case of success

virDomainGetUUIDString ()

int	virDomainGetUUIDString		(virDomainPtr domain, 
char * buf)

Get the UUID for a domain as string. For more information about UUID see RFC4122.

domain:a domain object
buf:pointer to a VIR_UUID_STRING_BUFLEN bytes array
Returns:-1 in case of error, 0 in case of success

virDomainGetVcpus ()

int	virDomainGetVcpus		(virDomainPtr domain, 
virVcpuInfoPtr info,
int maxinfo,
unsigned char * cpumaps,
int maplen)

Extract information about virtual CPUs of domain, store it in info array and also in cpumaps if this pointer is'nt NULL.

domain:pointer to domain object, or NULL for Domain0
info:pointer to an array of virVcpuInfo structures (OUT)
maxinfo:number of structures in info array
cpumaps:pointer to an bit map of real CPUs for all vcpus of this domain (in 8-bit bytes) (OUT) If cpumaps is NULL, then no cupmap information is returned by the API. It's assumed there is <maxinfo> cpumap in cpumaps array. The memory allocated to cpumaps must be (maxinfo * maplen) bytes (ie: calloc(maxinfo, maplen)). One cpumap inside cpumaps has the format described in virDomainPinVcpu() API.
maplen:number of bytes in one cpumap, from 1 up to size of CPU map in underlying virtualization system (Xen...).
Returns:the number of info filled in case of success, -1 in case of failure.

virDomainGetXMLDesc ()

char *	virDomainGetXMLDesc		(virDomainPtr domain, 
int flags)

Provide an XML description of the domain. The description may be reused later to relaunch the domain with virDomainCreateLinux().

domain:a domain object
flags:an OR'ed set of virDomainXMLFlags
Returns:a 0 terminated UTF-8 encoded XML instance, or NULL in case of error. the caller must free() the returned value.

virDomainInterfaceStats ()

int	virDomainInterfaceStats		(virDomainPtr dom, 
const char * path,
virDomainInterfaceStatsPtr stats,
size_t size)

This function returns network interface stats for interfaces attached to the domain. The path parameter is the name of the network interface. Domains may have more than network interface. To get stats for each you should make multiple calls to this function. Individual fields within the stats structure may be returned as -1, which indicates that the hypervisor does not support that particular statistic.

dom:pointer to the domain object
path:path to the interface
stats:network interface stats (returned)
size:size of stats structure
Returns:0 in case of success or -1 in case of failure.

virDomainLookupByID ()

virDomainPtr	virDomainLookupByID	(virConnectPtr conn, 
int id)

Try to find a domain based on the hypervisor ID number

conn:pointer to the hypervisor connection
id:the domain ID number
Returns:a new domain object or NULL in case of failure. If the domain cannot be found, then VIR_ERR_NO_DOMAIN error is raised.

virDomainLookupByName ()

virDomainPtr	virDomainLookupByName	(virConnectPtr conn, 
const char * name)

Try to lookup a domain on the given hypervisor based on its name.

conn:pointer to the hypervisor connection
name:name for the domain
Returns:a new domain object or NULL in case of failure. If the domain cannot be found, then VIR_ERR_NO_DOMAIN error is raised.

virDomainLookupByUUID ()

virDomainPtr	virDomainLookupByUUID	(virConnectPtr conn, 
const unsigned char * uuid)

Try to lookup a domain on the given hypervisor based on its UUID.

conn:pointer to the hypervisor connection
uuid:the raw UUID for the domain
Returns:a new domain object or NULL in case of failure. If the domain cannot be found, then VIR_ERR_NO_DOMAIN error is raised.

virDomainLookupByUUIDString ()

virDomainPtr	virDomainLookupByUUIDString	(virConnectPtr conn, 
const char * uuidstr)

Try to lookup a domain on the given hypervisor based on its UUID.

conn:pointer to the hypervisor connection
uuidstr:the string UUID for the domain
Returns:a new domain object or NULL in case of failure. If the domain cannot be found, then VIR_ERR_NO_DOMAIN error is raised.

virDomainMigrate ()

virDomainPtr	virDomainMigrate	(virDomainPtr domain, 
virConnectPtr dconn,
unsigned long flags,
const char * dname,
const char * uri,
unsigned long bandwidth)

Migrate the domain object from its current host to the destination host given by dconn (a connection to the destination host). Flags may be one of more of the following: VIR_MIGRATE_LIVE Attempt a live migration. If a hypervisor supports renaming domains during migration, then you may set the dname parameter to the new name (otherwise it keeps the same name). If this is not supported by the hypervisor, dname must be NULL or else you will get an error. Since typically the two hypervisors connect directly to each other in order to perform the migration, you may need to specify a path from the source to the destination. This is the purpose of the uri parameter. If uri is NULL, then libvirt will try to find the best method. Uri may specify the hostname or IP address of the destination host as seen from the source. Or uri may be a URI giving transport, hostname, user, port, etc. in the usual form. Refer to driver documentation for the particular URIs supported. The maximum bandwidth (in Mbps) that will be used to do migration can be specified with the bandwidth parameter. If set to 0, libvirt will choose a suitable default. Some hypervisors do not support this feature and will return an error if bandwidth is not 0. To see which features are supported by the current hypervisor, see virConnectGetCapabilities, /capabilities/host/migration_features. There are many limitations on migration imposed by the underlying technology - for example it may not be possible to migrate between different processors even with the same architecture, or between different types of hypervisor.

domain:a domain object
dconn:destination host (a connection object)
flags:flags
dname:(optional) rename domain to this at destination
uri:(optional) dest hostname/URI as seen from the source host
bandwidth:(optional) specify migration bandwidth limit in Mbps
Returns:the new domain object if the migration was successful, or NULL in case of error. Note that the new domain object exists in the scope of the destination connection (dconn).

virDomainPinVcpu ()

int	virDomainPinVcpu		(virDomainPtr domain, 
unsigned int vcpu,
unsigned char * cpumap,
int maplen)

Dynamically change the real CPUs which can be allocated to a virtual CPU. This function requires priviledged access to the hypervisor.

domain:pointer to domain object, or NULL for Domain0
vcpu:virtual CPU number
cpumap:pointer to a bit map of real CPUs (in 8-bit bytes) (IN) Each bit set to 1 means that corresponding CPU is usable. Bytes are stored in little-endian order: CPU0-7, 8-15... In each byte, lowest CPU number is least significant bit.
maplen:number of bytes in cpumap, from 1 up to size of CPU map in underlying virtualization system (Xen...). If maplen < size, missing bytes are set to zero. If maplen > size, failure code is returned.
Returns:0 in case of success, -1 in case of failure.

virDomainReboot ()

int	virDomainReboot			(virDomainPtr domain, 
unsigned int flags)

Reboot a domain, the domain object is still usable there after but the domain OS is being stopped for a restart. Note that the guest OS may ignore the request.

domain:a domain object
flags:extra flags for the reboot operation, not used yet
Returns:0 in case of success and -1 in case of failure.

virDomainRestore ()

int	virDomainRestore		(virConnectPtr conn, 
const char * from)

This method will restore a domain saved to disk by virDomainSave().

conn:pointer to the hypervisor connection
from:path to the
Returns:0 in case of success and -1 in case of failure.

virDomainResume ()

int	virDomainResume			(virDomainPtr domain)

Resume an suspended domain, the process is restarted from the state where it was frozen by calling virSuspendDomain(). This function may requires priviledged access

domain:a domain object
Returns:0 in case of success and -1 in case of failure.

virDomainSave ()

int	virDomainSave			(virDomainPtr domain, 
const char * to)

This method will suspend a domain and save its memory contents to a file on disk. After the call, if successful, the domain is not listed as running anymore (this may be a problem). Use virDomainRestore() to restore a domain after saving.

domain:a domain object
to:path for the output file
Returns:0 in case of success and -1 in case of failure.

virDomainSetAutostart ()

int	virDomainSetAutostart		(virDomainPtr domain, 
int autostart)

Configure the domain to be automatically started when the host machine boots.

domain:a domain object
autostart:whether the domain should be automatically started 0 or 1
Returns:-1 in case of error, 0 in case of success

virDomainSetMaxMemory ()

int	virDomainSetMaxMemory		(virDomainPtr domain, 
unsigned long memory)

Dynamically change the maximum amount of physical memory allocated to a domain. If domain is NULL, then this change the amount of memory reserved to Domain0 i.e. the domain where the application runs. This function requires priviledged access to the hypervisor.

domain:a domain object or NULL
memory:the memory size in kilobytes
Returns:0 in case of success and -1 in case of failure.

virDomainSetMemory ()

int	virDomainSetMemory		(virDomainPtr domain, 
unsigned long memory)

Dynamically change the target amount of physical memory allocated to a domain. If domain is NULL, then this change the amount of memory reserved to Domain0 i.e. the domain where the application runs. This function may requires priviledged access to the hypervisor.

domain:a domain object or NULL
memory:the memory size in kilobytes
Returns:0 in case of success and -1 in case of failure.

virDomainSetSchedulerParameters ()

int	virDomainSetSchedulerParameters	(virDomainPtr domain, 
virSchedParameterPtr params,
int nparams)

Change the scheduler parameters

domain:pointer to domain object
params:pointer to scheduler parameter objects
nparams:number of scheduler parameter (this value should be same or less than the returned value nparams of virDomainGetSchedulerType)
Returns:-1 in case of error, 0 in case of success.

virDomainSetVcpus ()

int	virDomainSetVcpus		(virDomainPtr domain, 
unsigned int nvcpus)

Dynamically change the number of virtual CPUs used by the domain. Note that this call may fail if the underlying virtualization hypervisor does not support it or if growing the number is arbitrary limited. This function requires priviledged access to the hypervisor.

domain:pointer to domain object, or NULL for Domain0
nvcpus:the new number of virtual CPUs for this domain
Returns:0 in case of success, -1 in case of failure.

virDomainShutdown ()

int	virDomainShutdown		(virDomainPtr domain)

Shutdown a domain, the domain object is still usable there after but the domain OS is being stopped. Note that the guest OS may ignore the request. TODO: should we add an option for reboot, knowing it may not be doable in the general case ?

domain:a domain object
Returns:0 in case of success and -1 in case of failure.

virDomainSuspend ()

int	virDomainSuspend		(virDomainPtr domain)

Suspends an active domain, the process is frozen without further access to CPU resources and I/O but the memory used by the domain at the hypervisor level will stay allocated. Use virDomainResume() to reactivate the domain. This function may requires priviledged access.

domain:a domain object
Returns:0 in case of success and -1 in case of failure.

virDomainUndefine ()

int	virDomainUndefine		(virDomainPtr domain)

undefine a domain but does not stop it if it is running

domain:pointer to a defined domain
Returns:0 in case of success, -1 in case of error



virNetworkCreate ()

int	virNetworkCreate		(virNetworkPtr network)

Create and start a defined network. If the call succeed the network moves from the defined to the running networks pools.

network:pointer to a defined network
Returns:0 in case of success, -1 in case of error

virNetworkCreateXML ()

virNetworkPtr	virNetworkCreateXML	(virConnectPtr conn, 
const char * xmlDesc)

Create and start a new virtual network, based on an XML description similar to the one returned by virNetworkGetXMLDesc()

conn:pointer to the hypervisor connection
xmlDesc:an XML description of the network
Returns:a new network object or NULL in case of failure

virNetworkDefineXML ()

virNetworkPtr	virNetworkDefineXML	(virConnectPtr conn, 
const char * xml)

Define a network, but does not create it

conn:pointer to the hypervisor connection
xml:the XML description for the network, preferably in UTF-8
Returns:NULL in case of error, a pointer to the network otherwise

virNetworkDestroy ()

int	virNetworkDestroy		(virNetworkPtr network)

Destroy the network object. The running instance is shutdown if not down already and all resources used by it are given back to the hypervisor. The data structure is freed and should not be used thereafter if the call does not return an error. This function may requires priviledged access

network:a network object
Returns:0 in case of success and -1 in case of failure.

virNetworkFree ()

int	virNetworkFree			(virNetworkPtr network)

Free the network object. The running instance is kept alive. The data structure is freed and should not be used thereafter.

network:a network object
Returns:0 in case of success and -1 in case of failure.

virNetworkGetAutostart ()

int	virNetworkGetAutostart		(virNetworkPtr network, 
int * autostart)

Provides a boolean value indicating whether the network configured to be automatically started when the host machine boots.

network:a network object
autostart:the value returned
Returns:-1 in case of error, 0 in case of success

virNetworkGetBridgeName ()

char *	virNetworkGetBridgeName		(virNetworkPtr network)

Provides a bridge interface name to which a domain may connect a network interface in order to join the network.

network:a network object
Returns:a 0 terminated interface name, or NULL in case of error. the caller must free() the returned value.

virNetworkGetConnect ()

virConnectPtr	virNetworkGetConnect	(virNetworkPtr net)

Provides the connection pointer associated with a network. The reference counter on the connection is not increased by this call. WARNING: When writing libvirt bindings in other languages, do not use this function. Instead, store the connection and the network object together.

net:pointer to a network
Returns:the virConnectPtr or NULL in case of failure.

virNetworkGetName ()

const char *	virNetworkGetName	(virNetworkPtr network)

Get the public name for that network

network:a network object
Returns:a pointer to the name or NULL, the string need not be deallocated its lifetime will be the same as the network object.

virNetworkGetUUID ()

int	virNetworkGetUUID		(virNetworkPtr network, 
unsigned char * uuid)

Get the UUID for a network

network:a network object
uuid:pointer to a VIR_UUID_BUFLEN bytes array
Returns:-1 in case of error, 0 in case of success

virNetworkGetUUIDString ()

int	virNetworkGetUUIDString		(virNetworkPtr network, 
char * buf)

Get the UUID for a network as string. For more information about UUID see RFC4122.

network:a network object
buf:pointer to a VIR_UUID_STRING_BUFLEN bytes array
Returns:-1 in case of error, 0 in case of success

virNetworkGetXMLDesc ()

char *	virNetworkGetXMLDesc		(virNetworkPtr network, 
int flags)

Provide an XML description of the network. The description may be reused later to relaunch the network with virNetworkCreateXML().

network:a network object
flags:and OR'ed set of extraction flags, not used yet
Returns:a 0 terminated UTF-8 encoded XML instance, or NULL in case of error. the caller must free() the returned value.

virNetworkLookupByName ()

virNetworkPtr	virNetworkLookupByName	(virConnectPtr conn, 
const char * name)

Try to lookup a network on the given hypervisor based on its name.

conn:pointer to the hypervisor connection
name:name for the network
Returns:a new network object or NULL in case of failure. If the network cannot be found, then VIR_ERR_NO_NETWORK error is raised.

virNetworkLookupByUUID ()

virNetworkPtr	virNetworkLookupByUUID	(virConnectPtr conn, 
const unsigned char * uuid)

Try to lookup a network on the given hypervisor based on its UUID.

conn:pointer to the hypervisor connection
uuid:the raw UUID for the network
Returns:a new network object or NULL in case of failure. If the network cannot be found, then VIR_ERR_NO_NETWORK error is raised.

virNetworkLookupByUUIDString ()

virNetworkPtr	virNetworkLookupByUUIDString	(virConnectPtr conn, 
const char * uuidstr)

Try to lookup a network on the given hypervisor based on its UUID.

conn:pointer to the hypervisor connection
uuidstr:the string UUID for the network
Returns:a new network object or NULL in case of failure. If the network cannot be found, then VIR_ERR_NO_NETWORK error is raised.

virNetworkSetAutostart ()

int	virNetworkSetAutostart		(virNetworkPtr network, 
int autostart)

Configure the network to be automatically started when the host machine boots.

network:a network object
autostart:whether the network should be automatically started 0 or 1
Returns:-1 in case of error, 0 in case of success

virNetworkUndefine ()

int	virNetworkUndefine		(virNetworkPtr network)

Undefine a network but does not stop it if it is running

network:pointer to a defined network
Returns:0 in case of success, -1 in case of error

virNodeGetCellsFreeMemory ()

int	virNodeGetCellsFreeMemory	(virConnectPtr conn, 
unsigned long long * freeMems,
int startCell,
int maxCells)

This call returns the amount of free memory in one or more NUMA cells. The @freeMems array must be allocated by the caller and will be filled with the amount of free memory in kilobytes for each cell requested, starting with startCell (in freeMems[0]), up to either (startCell + maxCells), or the number of additional cells in the node, whichever is smaller.

conn:pointer to the hypervisor connection
freeMems:pointer to the array of unsigned long long
startCell:index of first cell to return freeMems info on.
maxCells:Maximum number of cells for which freeMems information can be returned.
Returns:the number of entries filled in freeMems, or -1 in case of error.

virNodeGetFreeMemory ()

unsigned long long	virNodeGetFreeMemory	(virConnectPtr conn)

provides the free memory availble on the Node

conn:pointer to the hypervisor connection
Returns:the available free memory in kilobytes or 0 in case of error

virNodeGetInfo ()

int	virNodeGetInfo			(virConnectPtr conn, 
virNodeInfoPtr info)

Extract hardware information about the node.

conn:pointer to the hypervisor connection
info:pointer to a virNodeInfo structure allocated by the user
Returns:0 in case of success and -1 in case of failure.