alloc_ring(9)

📦 version 7.3.1, in nixpkgs unstable

🦋 alloc_ring(9) — the Kernel API Manual page your bestie actually wants to read

okay so real talk, we're in the Kernel API Manual today and this little function is genuinely iconic 💅 it's called alloc_ring and it's about to set up a whole SGE descriptor ring for you. no cap.

✨ NAME ✨

alloc_ring — allocate resources for an SGE descriptor ring 💖

🌸 SYNOPSIS 🌸

void * alloc_ring (struct device *dev , size_t nelem , size_t hwsize ,
size_t swsize , dma_addr_t *busaddrp , void *swringp , size_t stat_size
);

like, that's the whole vibe. seven args. she's thorough 👑

🎀 ARGUMENTS 🎀

  • dev — the PCI device's core device. it's giving "who's your parent" energy 🫶
  • nelem — the number of descriptors. how many lil entries we're making room for ✨
  • hwsize — the size of each hardware descriptor. the hardware side's personal space 📏
  • swsize — the size of each software descriptor. same but for the software girlies 🩷
  • busaddrp — the physical PCI bus address of the allocated ring. it gets written in here 📮
  • swringp — return address pointer for software ring. yep, another out-param, she's generous 😭
  • stat_size — extra space in the hardware ring for status information. little extra room for lore 🗂️

🔥 DESCRIPTION 🔥

so what does she actually do? alloc_ring allocates resources for an SGE descriptor ring — think TX queues, free buffer lists, response queues, etc. basically all the ring-flavored stuff 💫

every SGE ring needs space for its hardware descriptors, plus — optionally — space for software state that's associated with each hardware entry, aka the metadata. so it's hardware ring + maybe-sw ring, living their best lives together 🫶

and here's the part that ate: the function returns three values 💅

  1. the virtual address for the hardware ring — that's the function's actual return value, main character energy 👑
  2. the PCI bus address of the hardware ring — handed back in *busaddrp
  3. the address of the software ring — handed back in swringp

and the best bit? both the hardware and software rings come back zeroed out ✨ clean slate, no leftover exes, we love a fresh start 🌈

💜 SEE ALSO 💜

heads up bestie, this list is long and I am NOT skipping a single one, every link is a real one 🫡

and that's the page, bestie 🎀 this lil drop came from ./drivers/net/ethernet/chelsio... and she's dated October 2026 — go forth, allocate responsibly, and remember: zeroed rings are the only rings we stan 💅✨

📦 where this page comes from