STRUCT CCW0(9)

💅 struct ccw0(9) — channel command word ✨

okay bestie, welcome to the Kernel API Manual entry for struct ccw0(9) 💖 this is the channel command word, and we’re about to get into its whole lil layout. no cap, it’s giving classic kernel struct energy 🎀

🌸 NAME 🌸

struct ccw0 — channel command word 🦋

✨ SYNOPSIS ✨

       struct ccw0 {
           __u8 cmd_code;
           __u32 cda : 24;
           __u8 flags;
           __u8 reserved;
           __u16 count;
        };

🫶 Members 🫶

member by member, let’s go 💅

• cmd_code — command code.
• cda — data address.
• flags — flags, like IDA addressing, etc.
• reserved — will be ignored. 🙈
• count — byte count.

💖 Description 💖

it’s the format-0 ccw structure. that’s the whole description, and honestly? iconic. periodt 💜

👑 SEE ALSO 👑

peep the kernel file ./arch/s390/include/asm/cio.h and these related pages, bestie:

• struct ccw1(9)
• struct erw(9)
• struct erw_eadm(9)
• struct sublog(9)
• struct esw0(9)
• struct esw1(9)
• struct esw2(9)
• struct esw3(9)
• struct esw_eadm(9)
• struct irb(9)
• struct ciw(9)
• struct ccw_dev_id(9)
• ccw_dev_id_is_equal(9)
• pathmask_to_pos(9)

and that’s the tea ☕ source/version is ./arch/s390/include/asm, dated October 2026, for struct ccw0(9) — mwah 💋✨