VM_MAP_INSERT(9)

💖 VM_MAP_INSERT(9) 💖

okay bestie, so this one's a page from the Kernel Developer's Manual — yes, the actual grown-up kernel manual, and yes, we're gonna make it cute anyway. it's all about vm_map_insert(), and it's genuinely iconic. let's get into it. 🦋

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✨ NAME ✨

vm_map_insert — insert an object into a map

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🌸 SYNOPSIS 🌸

first, the vibes: you gotta bring in the right headers, no skipping, that's the rules 💅

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

int
vm_map_insert(vm_map_t map, vm_object_t object, vm_ooffset_t offset,
    vm_offset_t start, vm_offset_t end, vm_prot_t prot, vm_prot_t max,
    int cow);

like. look at all those arguments. she's busy, she's booked, she's thriving. 👑

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🎀 DESCRIPTION 🎀

so what does vm_map_insert() actually do, you ask? she takes a whole entire vm_object — we're calling it object — and she inserts a mapping for the entire thing into the target map, which we're calling map. no crumbs left, the whole object, periodt. ✨

the offset argument is doing the "okay but where do we start" job — it says which offset into the object we begin mapping at. and heads up: the object's size should match the size of the address range you specified. like, they should be giving matching energy. 🫶

then start and end come through and set the bounds of the mapped object's window in the address space of map. that's the window. that's the little viewing portal. 🌈

and cow? that one specifies the flags that should get propagated to the new entry — for example, to say "hey, this is a copy-on-write mapping." so like, the flag gossip gets passed down to the new entry, iykyk. 🐄

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💀 IMPLEMENTATION NOTES 💀

not me telling you the behind-the-scenes tea, but: this function implicitly creates a new vm_map_entry by calling the internal function vm_map_entry_create(). like she doesn't even ask, she just does it. main character behavior fr fr. ✨

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🍓 RETURN VALUES 🍓

so did it work? here's the receipt:

• vm_map_insert() returns KERN_SUCCESS if the mapping could be made successfully. slay. 💖

and if it didn't work, you get one of these instead:

• KERN_INVALID_ADDRESS — returned if the start of the range could not be found.
• KERN_NO_SPACE — returned if the range was found to be part of an existing entry, or if it overlaps the end of the map.

ok so important: if you get KERN_NO_SPACE it means the space is taken — either it's already part of an existing entry, or it's overlapping the end of the map. either way, that spot is occupied, no cap. 😭

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👑 SEE ALSO 👑

• vm_map(9)

go read that one too, bestie, they're a set. 🎀

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🌟 AUTHORS 🌟

this manual page was written by Bruce M Simpson <bms@spc.org>. thank you bruce, king behavior, we appreciate you. 🙈💜

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and that's the whole page, angel — originally from the <strong>Debian</strong> crew, dated <strong>January 11, 2013</strong>, filed under VM_MAP_INSERT(9) in section 9. go forth and map responsibly. mwah. 💅🌸