ccw_device_get_mdc(9)

💖 ccw_device_get_mdc(9) — Kernel API Manual 💖

okay so bestie, welcome to the Kernel API Manual page for ccw_device_get_mdc(9). It's a lil kernel helper with main-character energy, and its whole thing is accumulating the max data count. Let's get into it ✨

💖 NAME 💖

ccw_device_get_mdc — accumulate max data count

✨ SYNOPSIS ✨

int ccw_device_get_mdc (struct ccw_device *cdev , u8 mask );

🎀 ARGUMENTS 🎀

• cdev — the ccw device for which the max data count is accumulated. This is the device we're doing the math for 👑
• mask — mask of paths to use. Yep, it's literally the path mask, no cap 🌈

🦋 DESCRIPTION 🦋

So this returns the number of 64K-bytes blocks that all paths at least support for a transport command. Like, every path has to be able to handle that many blocks, or it doesn't count — it's giving "lowest common denominator but make it kernel" 💅

And if the return value is 0, that indicates failure. Not the vibe 😭

🌸 SEE ALSO 🌸

• Kernel file — ./drivers/s390/cio/device_ops.c
• ccw_device_set_options_mask(9)
• ccw_device_set_options(9)
• ccw_device_clear_options(9)
• ccw_device_is_pathgroup(9)
• ccw_device_is_multipath(9)
• ccw_device_clear(9)
• ccw_device_start_timeout_key(9)
• ccw_device_start_key(9)
• ccw_device_start(9)
• ccw_device_start_timeout(9)
• ccw_device_halt(9)
• ccw_device_resume(9)
• ccw_device_get_ciw(9)
• ccw_device_get_path_mask(9)
• ccw_device_get_chp_desc(9)
• ccw_device_get_util_str(9)
• ccw_device_get_id(9)
• ccw_device_tm_start_timeout_key(9)
• ccw_device_tm_start_key(9)
• ccw_device_tm_start(9)
• ccw_device_tm_start_timeout(9)
• ccw_device_tm_intrg(9)
• ccw_device_get_schid(9)
• ccw_device_pnso(9)
• ccw_device_get_cssid(9)
• ccw_device_get_iid(9)
• ccw_device_get_chpid(9)
• ccw_device_get_chid(9)

that's the whole page, bestie 🫶 source/version: ./drivers/s390/cio; date: October 2026; manual: Kernel API Manual; page: ccw_device_get_mdc(9). byeee 💋