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Host Information

Function: mach_port_t mach_host_self ()

The mach_host_self system call returns the calling thread's host port. It has an effect equivalent to receiving a send right for the host port. mach_host_self returns the name of the send right. In particular, successive calls will increase the calling task's user-reference count for the send right.

As a special exception, the kernel will happily overrun the user reference count of the host name port, so that this function can not fail for that reason. Because of this, the user should not deallocate the port right if an overrun might have happened. Otherwise the reference count could drop to zero and the send right be destroyed while the user still expects to be able to use it. As the kernel does not make use of the number of extant send rights anyway, this is safe to do (the host port itself is never destroyed).

The function returns MACH_PORT_NULL if a resource shortage prevented the reception of the send right.

This function is also available in `mach/mach_traps.h'.

Function: kern_return_t host_info (mach_port_t host, int flavor, host_info_t host_info, mach_msg_type_number_t *host_infoCnt)

The host_info function returns various information about host. host_info is an array of integers that is supplied by the caller, and filled with specified information. host_infoCnt is supplied as the maximum number of integers in host_info. On return, it contains the actual number of integers in host_info.

The type of information returned is defined by flavor, which can be one of the following:

HOST_BASIC_INFO

The function returns basic information about the host, as defined by host_basic_info_t. This includes the number of processors, their type, and the amount of memory installed in the system. The number of integers returned is HOST_BASIC_INFO_COUNT.

HOST_PROCESSOR_SLOTS

The function returns the numbers of the slots with active processors in them. The number of integers returned can be up to max_cpus, as returned by the HOT_BASIC_INFO flavor of host_info.

HOST_SCHED_INFO

The function returns information of interest to schedulers as defined by host_sched_info_t. The number of integers returned is HOST_SCHED_INFO_COUNT.

The function returns KERN_SUCCESS if the call succeeded and KERN_INVALID_ARGUMENT if host is not a host or flavor is not recognized. The function returns MIG_ARRAY_TOO_LARGE if the returned info array is too large for host_info. In this case, host_info is filled as much as possible and host_infoCnt is set to the number of elements that would be returned if there were enough room.

Data type: struct host_basic_info

A pointer to this structure is returned in host_info by the host_info function and provides basic information about the host. You can cast a variable of type host_info_t to a pointer of this type if you provided it as the host_info parameter for the HOST_BASIC_INFO flavor of host_info. It has the following members:

int max_cpus

maximum possible cpus for which kernel is configured

int avail_cpus

number of cpus now available

vm_size_t memory_size

size of memory in bytes

cpu_type_t cpu_type

cpu type

cpu_subtype_t cpu_subtype

cpu subtype

Data type: host_basic_info_t

This is a pointer to a struct host_basic_info.

Data type: struct host_sched_info

A pointer to this structure is returned in host_info by the host_info function and provides information of interest to schedulers. You can cast a variable of type host_info_t to a pointer of this type if you provided it as the host_info parameter for the HOST_SCHED_INFO flavor of host_info. It has the following members:

int min_timeout

minimum timeout in milliseconds

int min_quantum

minimum quantum in milliseconds

Data type: host_sched_info_t

This is a pointer to a struct host_sched_info.

Function: kern_return_t host_kernel_version (mach_port_t host, kernel_version_t *version)

The host_kernel_version function returns the version string compiled into the kernel executing on host at the time it was built in the character string version. This string describes the version of the kernel. The constant KERNEL_VERSION_MAX should be used to dimension storage for the returned string if the kernel_version_t declaration is not used.

If the version string compiled into the kernel is longer than KERNEL_VERSION_MAX, the result is truncated and not necessarily null-terminated.

If host is not a valid send right to a host port, the function returns KERN_INVALID_ARGUMENT. If version points to inaccessible memory, it returns KERN_INVALID_ADDRESS, and KERN_SUCCESS otherwise.

Function: kern_return_t host_get_boot_info (mach_port_t host_priv, kernel_boot_info_t boot_info)

The host_get_boot_info function returns the boot-time information string supplied by the operator to the kernel executing on host_priv in the character string boot_info. The constant KERNEL_BOOT_INFO_MAX should be used to dimension storage for the returned string if the kernel_boot_info_t declaration is not used.

If the boot-time information string supplied by the operator is longer than KERNEL_BOOT_INFO_MAX, the result is truncated and not necessarily null-terminated.

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