size_t len, int cmd,
void *arg, int attr,
memcntl() function allows the calling process to apply a variety of control operations over the address space identified by the mappings established for the address range [ addr, addr + len ).
The addr argument must be a multiple of the pagesize as returned by sysconf(3C). The scope of the control operations can be further defined with additional selection criteria (in the form of attributes) according to the bit pattern contained in attr.
The following attributes specify page mapping selection criteria:
The following attributes specify page protection selection criteria. The selection criteria are constructed by a bitwise OR operation on the attribute bits and must match exactly.
The following criteria may also be specified:
PROC_TEXT attribute specifies all
privately mapped segments with read and execute permission, and the
PROC_DATA attribute specifies all privately mapped
segments with write permission.
Selection criteria can be used to describe various abstract memory objects within the address space on which to operate. If an operation shall not be constrained by the selection criteria, attr must have the value 0.
The operation to be performed is identified by the argument
cmd. The symbolic names for the operations are defined
MAP_PRIVATEpage in the address range is changed, the lock will be transferred to the private page.
The arg argument is not used, but must
NULL to ensure compatibility with potential
NULLand 0 respectively, to ensure compatibility with potential future enhancements. The arg argument is a bit pattern built from the flags:
The value of arg determines whether the
pages to be locked are those currently mapped by the address space,
those that will be mapped in the future, or both. If
MCL_FUTURE is specified, then all mappings
subsequently added to the address space will be locked, provided
sufficient memory is available.
MAP_SHAREDmapping is the file the page is mapped to; the backing storage for a modified
MAP_PRIVATEmapping is its swap area. The arg argument is a bit pattern built from the flags used to control the behavior of the operation:
MS_SYNCis also specified).
NULLto ensure compatibility with potential future enhancements.
NULL, 0, and
NULL, respectively, to ensure compatibility with potential future enhancements.
uint_t mha_cmd; uint_t mha_flags; size_t mha_pagesize;
The accepted values for mha_cmd are:
MHA_MAPSIZE_VA MHA_MAPSIZE_STACK MHA_MAPSIZE_BSSBRK
The mha_flags member is reserved for future use and must always be set to 0. The mha_pagesize member must be a valid size as obtained from getpagesizes(3C) or the constant value 0 to allow the system to choose an appropriate hardware address translation mapping size.
MHA_MAPSIZE_VA sets the preferred
hardware address translation mapping size of the region of memory from
addr to addr +
len. Both addr and
len must be aligned to an
mha_pagesize boundary. The entire virtual address
region from addr to addr +
len must not have any holes. Permissions within
each mha_pagesize-aligned portion of the region
must be consistent. When a size of 0 is specified, the system selects an
appropriate size based on the size and alignment of the memory region,
type of processor, and other considerations.
MHA_MAPSIZE_STACK sets the preferred
hardware address translation mapping size of the process main thread
stack segment. The addr and
len arguments must be
and 0, respectively.
MHA_MAPSIZE_BSSBRK sets the preferred
hardware address translation mapping size of the process heap. The
addr and len arguments must
NULL and 0, respectively. See the NOTES
section of the ppgsz(1) manual page
for additional information on process heap alignment.
The attr argument must be 0 for all
The mask argument must be 0; it is reserved for future use.
Locks established with the lock operations are not inherited by a
child process after fork(2). The
memcntl() function fails if it attempts to lock more
memory than a system-specific limit.
Due to the potential impact on system resources, the operations
are restricted to privileged processes.
memcntl() function subsumes the operations of plock(3C).
MC_HAT_ADVISE is intended to improve
performance of applications that use large amounts of memory on processors
that support multiple hardware address translation mapping sizes; however,
it should be used with care. Not all processors support all sizes with equal
efficiency. Use of larger sizes may also introduce extra overhead that could
reduce performance or available memory. Using large sizes for one
application may reduce available resources for other applications and result
in slower system wide performance.
memcntl() returns 0. Otherwise, it returns -1 and sets errno to indicate an error.
memcntl() function will fail if:
MC_LOCKASwas specified, some or all mappings in the address range [addr, addr + len) are locked for I/O when
MC_HAT_ADVISEwas specified, or the system has insufficient resources when
The cmd is
locking the memory identified by this operation would exceed a limit or
resource control on locked memory.
MC_SYNC with the
MS_INVALIDATEoption was specified.
MC_UNLOCKASis specified; the arg argument is not valid for the function specified; mha_pagesize or mha_cmd is invalid; or
MC_HAT_ADVISEis specified and not all pages in the specified region have the same access permissions within the given size boundaries.
PRIV_PROC_LOCK_MEMORY} privilege is not asserted in the effective set of the calling process and
|March 13, 2022||OmniOS|