POSIX_SPAWNATTR_SETARCHPREF_NP(3)

NAME
posix_spawnattr_setarchpref_np posix_spawnattr_getarchpref_np - set or get the cpu/subcpu preference attribute on a posix_spawnattr_t

SYNOPSIS
#include <spawn.h>
int
posix_spawnattr_setarchpref_np(posix_spawnattr_t *restrict attr, size_t count, cpu_type_t *pref, cpu_subtype_t *subpref, size_t *restrict ocount);
int
posix_spawnattr_getarchpref_np(const posix_spawnattr_t *restrict attr, size_t count, cpu_type_t *pref, cpu_subtype_t *subpref, size_t * restrict ocount);

IMPORTANT
These functions represent an Apple extension to posix_spawn(2) and posix_spawnp(2), and as such should not be used by programs intending their code to be portable to other platforms.

DESCRIPTION
The posix_spawnattr_setarchpref_np() function sets the precise universal binary preferences for the spawn attribute value referenced by attr from the memory containing the cpu_type_t referenced by pref and the cpu_subtype_t referenced by subpref with a size of count elements; the actual number of elements that are set in the attribute is returned in ocount.

When spawn(2) or spawnp(2) is subsequently invoked on a Universal binary with the posix_spawnattr_t, the elements which were set will be used, in the order they were set, to select the first element in the list which matches any cpu_type_t and cpu_subtype_t of those available in the Universal binary. If there is no match, then the attempt to create the child process will fail with the error EBADARCH. If the cpu_type_t CPU_TYPE_ANY and cpu_subtype_t CPU_SUBTYPE_ANY are the last pair in the list, then rather than returning EBADARCH on no match, the system will instead fall back to the standard Universal binary grading preference order. Using CPU_SUBTYPE_ANY as a cpu_subtype_t for any cpu_type_t value will select the best slice for that specific cpu_type_t, similar to using posix_spawnattr_setbinpref_np(). If called multiple times on the same attr, the previous preferences will be overwritten.

The posix_spawnattr_getarchpref_np() function gets the precise universal binary preferences for the spawn attribute value referenced by attr (set by a prior call to posix_spawnattr_setbinpref_np() or posix_spawnattr_setarchpref_np()) into the memory containing the cpu_type_t referenced by pref and the cpu_subtype_t referenced by subpref with a prereserved size of count elements; the actual number of elements that are copied from the attribute is returned in ocount.

RETURN VALUES
On success, these functions return 0; on failure they return an error number from <errno.h> and modify the value of ocount. Additionally, if successful, posix_spawnattr_getarchpref_np() will modify the contents of the pref array with the current attribute values.

ERRORS
These functions may fail if:

[EINVAL]
    The value specified by attr is invalid.

[EINVAL]
    The value of attr is invalid.

SEE ALSO
posix_spawn(2), posix_spawnp(2), posix_spawnattr_init(3), posix_spawnattr_destroy(3), posix_spawnattr_setbinpref_np(3), posix_spawnattr_setflags(3)

STANDARDS
Nonstandard

HISTORY
The posix_spawnattr_setarchpref_np() and posix_spawnattr_getarchpref_np() function calls appeared in macOS 10.16