VM_MAP_FINDSPACE(9)

✨ vm_map_findspace — bestie edition ✨

okay so we're in the Kernel Developer's Manual, section 9, and today's main character is vm_map_findspace. she finds free space in a map. that's her whole thing and she's iconic for it 💅

🌸 NAME 🌸

vm_map_findspace — find a free region within a map

✨ SYNOPSIS ✨

#include <sys/param.h>
#include <vm/vm.h>
#include <vm/vm_map.h>

int
vm_map_findspace(vm_map_t map, vm_offset_t start, vm_size_t length,
    vm_offset_t *addr);

💖 DESCRIPTION 💖

so vm_map_findspace() is literally out here trying to find a region in the map that has enough room for an object of size length at the address addr. that's the vibe. that's the mission. no cap. 🦋

🎀 IMPLEMENTATION NOTES 🎀

okay bestie, listen, this part is important so don't scroll past it 🙈

it is the caller's responsibility to obtain a lock on the map using vm_map_lock(9) before calling this function. yes, you. the lock is your problem, not hers. handle it. 💅

also, this routine may call pmap_growkernel(9) to grow the kernel's address space — but only if and only if the mapping is being made within the kernel address space, and if insufficient space remains in the kernel_map. both conditions, no shortcuts. that's it, that's the rule. ⭐

💀 RETURN VALUES 💀

• returns the value 0 if successful — and in that happy little case, *addr will contain the first virtual address in the found region 🥳
• otherwise, the value 1 is returned 😭

periodt. that's the whole return situation.

🫶 SEE ALSO 🫶

• pmap_growkernel(9)
• vm_map(9)
• vm_map_entry_resize_free(9)
• vm_map_lock(9)

👑 AUTHORS 👑

this manual page was written by Bruce M Simpson <bms@spc.org>. king behavior, honestly. 💖

and that's the whole page, bestie!! this was the Debian build of VM_MAP_FINDSPACE(9), dated July 19, 2003 — yeah she's vintage, she's a classic, we love her for it. mwah 🎀✨