trace_s390_cio_msch(9)

📦 version 7.3.1, in nixpkgs unstable

💅 trace_s390_cio_msch — kernel API manual, but make it make sense 🎀

okay bestie, so this is a page from the Kernel API Manual, and honestly? It's a whole vibe. It's about a tracepoint — the one that fires when a Modify Subchannel instruction (MSCH) has been performed. That's it, that's the whole page. Short and iconic ✨

🌸 NAME 🌸

trace_s390_cio_msch — the tracepoint that says "hey, a Modify Subchannel instruction (MSCH) happened" 💖

Like, the whole personality of this function is literally just: MSCH was performed. Not me explaining kernel tracing at 2am 😭

✨ SYNOPSIS ✨

void trace_s390_cio_msch (struct subchannel_id schid , struct schib
*schib , int cc );

there she is 👑 — returns void, takes three things, no cap.

🫶 ARGUMENTS 🫶

  • schid — Subchannel ID 💅 like, which subchannel we're talking about
  • schib — Subchannel-Information block 🎀 the info block, struct schib * and everything
  • cc — Condition code ⭐ that little int that tells you how it went

three arguments, all accounted for, nothing skipped, we love a tidy parameter list 🌈

🦋 SEE ALSO 🦋

so this tracepoint does not live alone — she has a whole friend group, iykyk. First up, the kernel file she calls home:

  • ./drivers/s390/cio/trace.h — the actual file, and lowkey the main character of this reference 📁

and then the full clique of sibling tracepoints, all in that same ./drivers/s390/cio world:

that's twelve (12) siblings plus the header file, and yes I counted them all because we don't do "etc." in this house 💀 go read them, they're all giving s390 cio realness 🧚

fr fr though — if you're here for the MSCH tracepoint, you probably want the STSCH/TSCH ones too, so do yourself a favour and hit those pages 🫶

and that's the whole page, bestie 💜 no tricks, no hidden flags, no environment variables — just one tracepoint living her best life in the s390 CIO tracing family. 🌸

this little page came to you from ./drivers/s390/cio, dated October 2026, and it's the trace_s390_cio_msch(9) manual page — slay, go trace some subchannels ✨🎀🦋

📦 where this page comes from