Source: mem_darwin.go in package runtime


package runtime

import (
	"unsafe"
)

Don't split the stack as this function may be invoked without a valid G, which prevents us from allocating more stack.go:nosplit

func sysAlloc(n uintptr, sysStat *sysMemStat) unsafe.Pointer {
	v, err := mmap(nil, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_PRIVATE, -1, 0)
	if err != 0 {
		return nil
	}
	sysStat.add(int64(n))
	return v
}

MADV_FREE_REUSABLE is like MADV_FREE except it also propagates accounting information about the process to task_info.

	madvise(v, n, _MADV_FREE_REUSABLE)
}

MADV_FREE_REUSE is necessary to keep the kernel's accounting accurate. If called on any memory region that hasn't been MADV_FREE_REUSABLE'd, it's a no-op.

	madvise(v, n, _MADV_FREE_REUSE)
}

func sysHugePage(v unsafe.Pointer, n uintptr) {
}

Don't split the stack as this function may be invoked without a valid G, which prevents us from allocating more stack.go:nosplit

func sysFree(v unsafe.Pointer, n uintptr, sysStat *sysMemStat) {
	sysStat.add(-int64(n))
	munmap(v, n)
}

func sysFault(v unsafe.Pointer, n uintptr) {
	mmap(v, n, _PROT_NONE, _MAP_ANON|_MAP_PRIVATE|_MAP_FIXED, -1, 0)
}

func sysReserve(v unsafe.Pointer, n uintptr) unsafe.Pointer {
	p, err := mmap(v, n, _PROT_NONE, _MAP_ANON|_MAP_PRIVATE, -1, 0)
	if err != 0 {
		return nil
	}
	return p
}

const _ENOMEM = 12

func sysMap(v unsafe.Pointer, n uintptr, sysStat *sysMemStat) {
	sysStat.add(int64(n))

	p, err := mmap(v, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_FIXED|_MAP_PRIVATE, -1, 0)
	if err == _ENOMEM {
		throw("runtime: out of memory")
	}
	if p != v || err != 0 {
		throw("runtime: cannot map pages in arena address space")
	}