get_vaddr_frames(9)

💅 get_vaddr_frames(9) — like, the whole kernel API manual energy, bestie

okay so welcome to the glow-up of get_vaddr_frames, straight from your fave Kernel API Manual ✨ this one's a function page, so grab a strawberry drink 🍓 and let's get into it.

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🎀 NAME 🎀

get_vaddr_frames — maps virtual addresses to pfns. that's it, that's the vibe 🦋

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✨ SYNOPSIS ✨

int get_vaddr_frames (unsigned long start , unsigned int nr_frames ,
                      bool write , struct frame_vector *vec );

literally the whole signature, no cap 💅

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🌸 ARGUMENTS 🌸

• start — the starting user address. like, where the whole thing begins 👑
• nr_frames — number of pages / pfns from start to map. the count, the amount, the quantity 🧚
• write — the mapped address has write permission. yes, it's a bool, yes it's important 🔥
• vec — the struct frame_vector that receives the pages / pfns of the addresses mapped. it should have space for at least nr_frames entries, so pls size it right bestie 🙈

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🦋 DESCRIPTION 🦋

so what does this icon actually do? it maps virtual addresses starting from start and fills the vec structure with page frame numbers or page pointers to the corresponding pages — the choice depends on the type of the vma underlying the virtual address 👀

here's the tea, split by case:

• if start belongs to a normal vma, the function grabs a reference to each of the pages to pin them in memory 📌
• if start belongs to a VM_IO | VM_PFNMAP vma, we don't touch page structures and the caller must make sure pfns aren't reused for anything else while he is using them — that's on you, fr fr, this is the important warning part 💀

the function returns the number of pages mapped, which may be less than nr_frames. in particular it stops mapping if there are more vmas of different type underlying the specified range of virtual addresses. and when the function isn't able to map a single page, it returns an error 😭

note that get_vaddr_frames cannot follow VM_IO mappings. it used to be able to do that, but that could (racily) return non-refcounted pfns. so like... we don't do that anymore, and honestly good for us 💅

also this function takes care of grabbing mmap_lock as necessary — no need to do it yourself, she handles it 🫶

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💜 SEE ALSO 💜

• kernel file ./drivers/media/common/videobuf2/frame_vector.c
• put_vaddr_frames(9)
• frame_vector_to_pages(9)
• frame_vector_to_pfns(9)
• frame_vector_create(9)
• frame_vector_destroy(9)

go read those too, iykyk 🌈

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and that's the page, bestie 💖 sign-off time: this lil masterpiece lives in ./drivers/media/common/videobuf2, dated October 2026 — and honestly? iconic. periodt. 🌟