dma_map_sgtable(9)

✨ dma_map_sgtable(9) ✨

okay so bestie, we're in the Kernel API Manual today and this one is literally the glow-up your buffer needs before the DMA domain takes it to prom 💅

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💖 NAME 💖

dma_map_sgtable — maps the given buffer for DMA. that's it, that's the whole vibe 🦋

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🌸 SYNOPSIS 🌸

int dma_map_sgtable (struct device *dev , struct sg_table *sgt , enum
dma_data_direction dir , unsigned long attrs );

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🎀 ARGUMENTS 🎀

• dev — the device that's gonna perform the DMA operation. it's giving main character energy, everything revolves around it 👑
• sgt — the sg_table object that describes the buffer. your scatterlist's whole personality lives in here ✨
• dir — DMA direction. which way are we flowing, bestie 🌈
• attrs — optional DMA attributes for the map operation. the little extras, the accessories, the finishing touches 🎀

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🦋 DESCRIPTION 🦋

So what it does is map a buffer — one described by a scatterlist living inside the given sg_table object — for the dir DMA operation, done by the dev device. 🫶

After success, the ownership of the buffer gets transferred over to the DMA domain. like, the buffer has officially moved out 🚚✨ and that's the important part: before you touch that buffer with the CPU again, you have to call dma_sync_sgtable_for_cpu or dma_unmap_sgtable to move ownership of the buffer back to the CPU domain. no cap, this one matters — don't just grab the buffer and start poking at it 😭

Returns 0 on success or a negative error code on error. here's the error codes it supports, with their meanings, and yes you need to know all of them:

• -EINVAL — an invalid argument, unaligned access, or some other error in usage. it will not succeed if you retry it. periodt, don't retry 💀
• -ENOMEM — insufficient resources (like memory or IOVA space) to complete the mapping. this one should succeed if you retry later, so it's giving "not right now but maybe later" 🙈
• -EIO — legacy error code with an unknown meaning. eg. this is what you get back if a lower level call returned DMA_MAPPING_ERROR. the mystery icon, we don't know her reasons 🔥
• -EREMOTEIO — the DMA device cannot access P2PDMA memory specified in the sg_table. this will not succeed if retried. nope, not happening, close the tab 🚫

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🌟 SEE ALSO 🌟

Kernel file ./kernel/dma/mapping.c, plus the whole friend group:

• dmam_free_coherent(9)
• dmam_alloc_attrs(9)
• dma_map_sg_attrs(9)
• dma_need_unmap(9)
• dma_can_mmap(9)
• dma_mmap_attrs(9)
• dma_addressing_limited(9)

iykyk 💜

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and that's the whole page, bestie — brought to you from ./kernel/dma, dated October 2026, in the Kernel API Manual 🧚 go map some buffers responsibly, mwah 💋🍓