kvmgetinfo Kernel Service

Purpose

Retrieves Virtual Memory Manager (VMM) information.

Syntax

#include <sys/vminfo.h>

int kvmgetinfo ( void *out, int command, int arg)

Description

The kvmgetinfo kernel service returns the current value of certain VMM parameters.

Parameters

Item	Description
out	Specifies the address where VMM information should be returned.
command	Specifies which information should be returned. The valid values for the command parameter are decribed below: VMINFO The content of vminfo structure (described in sys/vminfo.h) will be returned. The out parameter should point to a vminfo structure and the arg parameter should be the size of this structure. The smaller of the arg or sizeof (struct vminfo) parameters will be copied. VMINFO_ABRIDGED The content of the vminfo structure (described in the sys/vminfo.h file) is returned. For this command, only the non-time consuming statistics are updated, so this command must be used in performance-critical applications rather than the VMINFO command. The out parameter must point to a vminfo structure and the arg parameter must be the size of this structure. The smaller of the arg or sizeof (struct vminfo) parameters are copied. VM_PAGE_INFO The size, in bytes, of the page backing the address specified in the addr field of the vm_page_info structure (described in the sys/vminfo.h file) is returned. The out parameter should point to a vm_page_info structure with the addr field set to the desired address of which to query the page size. This address, addr, is interpreted as an address in the address space of the current running process. The arg parameter should be the size of the vm_page_info structure. IPC_LIMITS The content of the ipc_limits struct (described in the sys/vminfo.h file) is returned. The out parameter should point to an ipc_limits structure and arg should be the size of this structure. The smaller of the arg or sizeof (struct ipc_limits) parameters will be copied. The ipc_limits struct contains the inter-process communication (IPC) limits for the system. VMINFO_GETPSIZES Reports a system’s supported page sizes. When arg is 0, the out parameter is ignored, and the number of supported page sizes is returned. When arg is greater than 0, arg indicates the number of page sizes to report, and out must be a pointer to an array with arg number of psize_t types. The array of psize_t types is updated with the system’s supported page sizes in sorted order starting with the smallest supported page size. The number of array entries updated with page sizes is returned. VMINFO_PSIZE Reports detailed VMM statistics for a specified page size. The out parameter must point to a vminfo_psize structure with the psize field set to a page size, in bytes, for which to return statistics. The arg parameter should be the size of the vminfo_psize structure.
arg	An additional parameter that will depend upon the command parameter.

Item

Description

out

Specifies the address where VMM information should be returned.

command

Specifies which information should be returned. The valid values for the command parameter are decribed below:

VMINFO: The content of vminfo structure (described in sys/vminfo.h) will be returned. The out parameter should point to a vminfo structure and the arg parameter should be the size of this structure. The smaller of the arg or sizeof (struct vminfo) parameters will be copied.
VMINFO_ABRIDGED: The content of the vminfo structure (described in the sys/vminfo.h file) is returned. For this command, only the non-time consuming statistics are updated, so this command must be used in performance-critical applications rather than the VMINFO command. The out parameter must point to a vminfo structure and the arg parameter must be the size of this structure. The smaller of the arg or sizeof (struct vminfo) parameters are copied.
VM_PAGE_INFO: The size, in bytes, of the page backing the address specified in the addr field of the vm_page_info structure (described in the sys/vminfo.h file) is returned. The out parameter should point to a vm_page_info structure with the addr field set to the desired address of which to query the page size. This address, addr, is interpreted as an address in the address space of the current running process. The arg parameter should be the size of the vm_page_info structure.
IPC_LIMITS: The content of the ipc_limits struct (described in the sys/vminfo.h file) is returned. The out parameter should point to an ipc_limits structure and arg should be the size of this structure. The smaller of the arg or sizeof (struct ipc_limits) parameters will be copied. The ipc_limits struct contains the inter-process communication (IPC) limits for the system.
VMINFO_GETPSIZES: Reports a system’s supported page sizes. When arg is 0, the out parameter is ignored, and the number of supported page sizes is returned. When arg is greater than 0, arg indicates the number of page sizes to report, and out must be a pointer to an array with arg number of psize_t types. The array of psize_t types is updated with the system’s supported page sizes in sorted order starting with the smallest supported page size. The number of array entries updated with page sizes is returned.
VMINFO_PSIZE: Reports detailed VMM statistics for a specified page size. The out parameter must point to a vminfo_psize structure with the psize field set to a page size, in bytes, for which to return statistics. The arg parameter should be the size of the vminfo_psize structure.

arg

An additional parameter that will depend upon the command parameter.

Execution Environment

The kvmgetinfo kernel service can be called from the process environment only.

Return Values

The following return values apply to all commands other than VMINFO_GETPSIZES:

Item	Description
0	Indicates successful completion.
ENOSYS	Indicates the command parameter is not valid (or not yet implemented).
EINVAL	When VM_PAGE_INFO is the command, the adr field of the vm_page_info structure is an invalid address.

When VMINFO_GETPSIZES is specified as the command, -1 is returned if the kvmgetinfo() kernel service is unsuccessful. Otherwise, the kvmgetinfo() kernel service returns a number of page sizes when the VMINFO_GETPSIZES command is specified.