scsi_dma_map(9)

💫 scsi_dma_map(9) 💫

okay so this is a page from the Kernel API Manual, bestie, and it's literally all about scsi_dma_map — the little function that does DMA mapping against a command's sg lists. it's giving "quiet hero of the SCSI layer" energy and i'm obsessed 🎀

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✨ NAME ✨

scsi_dma_map — perform DMA mapping against command's sg lists

like yes, that's the whole vibe: it takes your command's scatter-gather lists and gets them DMA-mapped. no cap. 🦋

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🌸 SYNOPSIS 🌸

int scsi_dma_map (struct scsi_cmnd *cmd );

that's it, that's the signature — copy it exactly, don't be cute with it 💅

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🎀 ARGUMENTS 🎀

• cmd — the scsi command. that's the one and only thing you hand over 🫶

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💖 DESCRIPTION 💖

okay so here's what you actually get back, and it's literally three possible situations:

• it returns the number of sg lists actually used — the good ending ✨
• it returns zero if the sg lists is NULL — nothing to map, so nothing to report 🌈
• it returns -ENOMEM if the mapping failed — the sad ending 😭

that's the entire contract, bestie. number of sg lists used, 0 for the NULL case, -ENOMEM when it goes wrong. periodt. 👑

fr fr read the return carefully — 0 and -ENOMEM are two completely different stories and you do not wanna mix them up 💀

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🔥 SEE ALSO 🔥

• Kernel file ./drivers/scsi/scsi_lib_dma.c — go read the source, it's right there 🧚
• scsi_dma_unmap(9) — the matching undo button, obviously you need both 💜

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and that's the page!! 💅 source/version is ./drivers/scsi and the date on this beauty is October 2026 — go forth and map those sg lists responsibly, mwah 🍓💖⭐