dma_contiguous_reserve_area(9)

📦 version 7.3.1, in nixpkgs unstable

💖 dma_contiguous_reserve_area(9) 💖

okay bestie, so this one's from the Kernel API Manual — literally the dma_contiguous_reserve_area(9) page itself, no cap. it's giving "arch code only, normies keep out" energy and i'm obsessed 🎀

✨ NAME ✨

dma_contiguous_reserve_area — reserve a custom contiguous area 🧚

🌸 SYNOPSIS 🌸

int dma_contiguous_reserve_area (phys_addr_t size , phys_addr_t base ,
       phys_addr_t limit , struct cma **res_cma , bool fixed );

like, that's the whole signature, copy it exactly please 💅

🦋 ARGUMENTS 🦋

  • size — size of the reserved area, in bytes. that's it, that's the vibe 💜
  • base — base address of the reserved area. it's optional, so if you don't care, just use 0 for any ✨
  • limit — end address of the reserved memory. also optional — 0 means any 🫶
  • res_cma — a pointer where the created cma region gets stored 👑
  • fixed — a lil hint about where to place the reserved area 🙈

💀 DESCRIPTION 💀

so this function reserves memory from the early allocator. main character behavior tbh.

it should be called by arch specific code — and listen, the timing matters fr fr: only once the early allocator (memblock or bootmem) has been activated and all other subsystems have already allocated/reserved memory. not before. do not come for it early 😭

what it does is let you create custom reserved areas for specific devices — bespoke, hand-picked, curated reserved area. it's giving couture 🌈

and here's the vibe check on fixed:

  • if fixed is true → reserve the contiguous area at exactly base. no negotiation, no wiggle room 💅
  • if fixed is false → reserve in range from base to limit. flexible queen ⭐

🔥 SEE ALSO 🔥

the kernel file ./kernel/dma/contiguous.c, plus the whole friend group of siblings:

go read them, iykyk 📚💖

and that's the page bestie!! 🎀 this one's from ./kernel/dma, dated October 2026 — that's the source and the date, mwah, love that for us 💋✨🦋

📦 where this page comes from