itcw_add_dcw(9)

💖 NAME 💖

itcw_add_dcw — add a dcw to the itcw. This is the itcw_add_dcw(9) page from the Kernel API Manual, and yes bestie, the whole assignment is “add a dcw to the itcw.” Iconic. Slay. 🎀✨

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🫶 SYNOPSIS 🫶

struct dcw * itcw_add_dcw (struct itcw *itcw , u8 cmd , u8 flags , void
       *cd , u8 cd_count , u32 count );

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💅 ARGUMENTS 💅

• itcw — address of the itcw 👑
• cmd — the dcw command ⭐
• flags — flags for the dcw 🚩
• cd — address of control data for this dcw, or NULL if none is required 🙈
• cd_count — number of control data bytes for this dcw 🔢
• count — number of data bytes for this dcw 🍓

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🌸 DESCRIPTION 🌸

okay so this function adds a new dcw to the specified itcw by writing the dcw information specified by cmd, flags, cd, cd_count and count to the tca of the tccb. That’s the whole main-character move, fr fr. 🦋

On success you get a pointer to the newly added dcw; if the new dcw would exceed the available space, you get -ENOSPC. That’s the space vibe check, and it does not pass 😭💀

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🎀 NOTE 🎀

heads up bestie: the tcal field of the tccb header will be updated to reflect added content. not me being obsessed with header bookkeeping 💅✨

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🔥 SEE ALSO 🔥

Kernel file ./drivers/s390/cio/itcw.c — plus itcw_get_tcw(9), itcw_calc_size(9), itcw_init(9), itcw_add_tidaw(9), itcw_set_data(9), and itcw_finalize(9). Go read those, iykyk 👑🌈

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later, bestie — signed with love from source/version ./drivers/s390/cio, dated October 2026, and this page is itcw_add_dcw(9). stay hydrated and may your tca always have room 💖✨