STRUCT VMEM_ALTMAP(9)

💖 struct vmem_altmap(9) 💖

okay bestie, welcome to the Kernel API Manual page for struct vmem_altmap — it's giving pre-allocated storage for vmemmap_populate, and we're keeping every last field. no cap. ✨

🌸 NAME 🌸

struct vmem_altmap — literally pre-allocated storage for vmemmap_populate. that's the whole name and the whole vibe, slay 🫶

🦋 SYNOPSIS 🦋

       struct vmem_altmap {
           unsigned long base_pfn;
           const unsigned long end_pfn;
           const unsigned long reserve;
           unsigned long free;
           unsigned long align;
           unsigned long alloc;
        };

🎀 Members 🎀

• base_pfn — base of the entire dev_pagemap mapping. like, the starting point, iykyk.
• reserve — pages mapped, but reserved for driver use (relative to base). mapped but set aside for the driver, bestie.
• free — free pages set aside in the mapping for memmap storage. the set-aside girlies 💅
• align — pages reserved to meet allocation alignments. alignment matters, fr fr.
• alloc — track pages consumed, private to vmemmap_populate. private means private — not for the group chat 🙈

also end_pfn is right there in the struct — this page just doesn't give it its own member line, and I'm not out here inventing facts 💀

🌈 SEE ALSO 🌈

• Kernel file ./include/linux/memremap.h
• struct dev_pagemap(9)

mwah 💋 — this page is from ./include/linux, October 2026. byeee 🫶