swiotlb_alloc_pool(9)

📦 version 7.3.1, in nixpkgs unstable

💖 swiotlb_alloc_pool(9) 💖

okay so bestie, we're in the <pink>Kernel API Manual</pink> today and the main character is swiotlb_alloc_pool — yes that's a 9 in the parens, that means kernel-internal function, we're in the deep docs now 🫶

✨ NAME ✨

swiotlb_alloc_pool — literally just allocate a brand new IO TLB memory pool, that's it, that's the whole vibe 💅

🌸 SYNOPSIS 🌸

struct io_tlb_pool * swiotlb_alloc_pool (struct device *dev , struct
io_tlb_mem *mem , unsigned long minslabs , unsigned long nslabs ,
unsigned int nareas , u64 phys_limit , gfp_t gfp );

seven (7) arguments, count 'em, she's a whole function signature 🔥

🎀 ARGUMENTS 🎀

  • dev — the device we're out here allocating a memory pool for. she's the reason we're all here ngl.
  • mem — the SWIOTLB allocator that owns this pool. the pool's home base, iykyk.
  • minslabs — the minimum number of slabs. this is the floor, we cannot go below it, no cap.
  • nslabs — the desired (aka maximum) number of slabs. we want this many, but see DESCRIPTION, she's flexible 🙈
  • nareas — how many areas. just... the number of areas bestie.
  • phys_limit — the maximum DMA buffer physical address. the ceiling, literally and physically 💀
  • gfp — the GFP flags used for the allocations. very important, do not skip.

🦋 DESCRIPTION 🦋

So what she does is: allocate and initialize a shiny new IO TLB memory pool ✨

the way that the actual number of slabs may be reduced if allocating nslabs fails... lowkey humbling. she'll take what she can get. BUT — and this is the important part — if even minslabs cannot be allocated, this function fails. periodt. no pool for you. 😭

so: trying for nslabs, settling is allowed, but going under minslabs is a hard no. 🚫

⭐ RETURN ⭐

The new memory pool 💖 — or NULL on allocation failure 😔 (it happens to the best of us).

🌈 SEE ALSO 🌈

Kernel file ./kernel/dma/swiotlb.c and its whole friend group:

she's got a lot of mutuals, we love a well-connected icon 👑

okay that's the whole page!! this one's from ./kernel/dma, dated October 2026, and if you need to find her again just look up swiotlb_alloc_pool(9) — mwah 💋🧚‍♀️

📦 where this page comes from