iosf_mbi_read(9)

📦 version 7.3.1, in nixpkgs unstable

💅 iosf_mbi_read — MailBox Interface read command

okay so bestie, welcome to the Kernel API Manual (section 9, very demure, very kernel) 💖 this one's all about iosf_mbi_read, the little function that goes and reads stuff over the MailBox Interface. yes it's giving "grab the data, no drama". let's get into it 🎀

✨ SYNOPSIS ✨

int iosf_mbi_read (u8 port , u8 opcode , u32 offset , u32 *mdr );

that's the whole vibe, literally one line 👑

🌸 ARGUMENTS 🌸

  • port — the port, aka which subunit we're poking at rn 🫶 this is the "where am I" of it all
  • opcode — a port-specific read or write opcode. yes, port-specific, so don't be out here assuming a universal one, iykyk 💅
  • offset — the register address offset. this is the exact spot in the register we're looking at ⭐
  • mdr — the register data that's gonna get read into this. it's a u32 *, so it's a pointer, so be normal about it 🙈

🦋 DESCRIPTION 🦋

so like, the big thing here: locking is handled by spinlock — which means it cannot sleep. NOT even a little. not a nap, not a lil blink. don't you dare call this from a context where sleeping is allowed, because the spinlock said no 💀 that's the entire description bestie, it's short but it ate 🔥

fr fr, "cannot sleep" is the whole personality of this function — treat it with main character respect 👑

🌈 RETURN 🌈

Nonzero on error ✨ so like, if it's nonzero, something went sideways, and zero means we're slaying 💖

🧚 SEE ALSO 🧚

Kernel file ./arch/x86/include/asm/iosf_mbi.h — go read it, it's right there, no cap 📖

the whole little iosf_mbi friend group, obsessed with them honestly 🫶✨

and that's the page, bestie 🎀 sourced straight from ./arch/x86/include/asm, dated October 2026 — mwah, go read some registers responsibly, ily 💜🌸

📦 where this page comes from