rh_string(9)

📦 version 7.3.1, in nixpkgs unstable

💖 rh_string(9) 💖

okay so bestie, welcome to the Kernel API Manual page for rh_string(9) — yes that's the whole name and no we're not shortening it, it's iconic like that ✨

🌸 NAME 🌸

rh_string — provides string descriptors for root hub 🫶

🎀 SYNOPSIS 🎀

unsigned rh_string (int id , struct usb_hcd const *hcd , u8 *data ,
unsigned len );

🦋 ARGUMENTS 🦋

  • id — the string ID number, and the vibes are very specific here: 0 means langids, 1 means serial #, 2 means product, 3 means vendor. that's it, that's the whole menu 💅
  • hcd — the host controller for this root hub, like the main character energy of the whole operation 👑
  • data — buffer for output packet, this is where the good stuff gets written bestie 🍓
  • len — length of the provided buffer, aka how much room you're giving it, no cap 🌈

✨ DESCRIPTION ✨

so what does it do? it produces either a manufacturer, product or serial number string for the virtual root hub device. literally that's the job. it's giving "I make strings for the fake root hub" and it ate 💀🔥

💜 RETURN 💜

it returns the number of bytes filled in — and here's the tea: it's the length of the descriptor or of the provided buffer, whichever is less. so nobody's overflowing anything on its watch, periodt 🙈

⭐ SEE ALSO ⭐

go look at the kernel file ./drivers/usb/core/hcd.c and honestly just go on a whole little journey through these, because there's a lot of them and every single one is getting its moment:

like okay go off, read the whole family 💖

and that's the page!! this little gem lives in ./drivers/usb/core, it's dated October 2026, and the whole thing goes by rh_string(9) — mwah, slay, bye bestie 🧚💜

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