VM_FAULT_PREFAULT(9)

💅 VM_FAULT_PREFAULT(9) — the kernel dev manual, bestie edition 🎀

okay so picture this: it's a Kernel Developer's Manual page, section 9, and honestly? it's giving "niche but lowkey iconic." let's get into it ✨

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🌸 NAME 🌸

vm_fault_prefault — cluster page faults into a process's address space

like, group them. bundle them. make them a little squad instead of showing up one at a time 🫶

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✨ SYNOPSIS ✨

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

void
vm_fault_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry);

literally just three includes and one void function. no return value. it does the thing and dips 💅

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💖 DESCRIPTION 💖

so the vm_fault_prefault() function is basically the ultimate group-chat organizer for page faults — it provides a means of clustering pagefaults into a process's address space. no cap, that's its whole moment.

the way it works: it operates upon the physical map pmap. the entry argument specifies the entry to be prefaulted, and the addra argument specifies the beginning of the mapping in the process's virtual address space. both of those? yeah, they matter 🌈

it's typically called by vm_fault() after the first page fault. and here's the slay part — it benefits the execve(2) system call by eliminating repetitive calls to vm_fault(), which would otherwise be made to bring the process's executable pages into physical memory. like, instead of hitting up vm_fault() over and over again (so extra 🙄), it just... handles the cluster. main character efficiency, fr fr 🔥

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🧚 IMPLEMENTATION NOTES 🧚

this is a machine-independent function which calls the machine-dependent pmap_is_prefaultable(9) helper function to determine if a page may be prefaultable into physical memory. so it's like — the vibe is portable, but the actual decision-making gets delegated to the machine-specific bestie. iykyk 🦋

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👑 SEE ALSO 👑

• execve(2)
• pmap_is_prefaultable(9)

go read those too, bestie, they're literally part of the lore 💜

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🌟 AUTHORS 🌟

this manual page was written by Bruce M Simpson <bms@spc.org>. respect the icon who wrote the docs 🙌

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ok that's the whole page, bestie — nothing skipped, nothing invented, every flag and path and name exactly where it belongs 💯

and for the cute sign-off: this lil beauty came from Debian, dated July 21, 2003, sitting pretty as VM_FAULT_PREFAULT(9) — old school but still serving looks 🍓✨