dma_alloc_from_dev_coherent(9)

💖 dma_alloc_from_dev_coherent(9) 💖

okay so bestie, welcome to the Kernel API Manual — this one's called dma_alloc_from_dev_coherent, and it's literally about allocating memory from a device coherent pool. no cap. let's get into it 🫶

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✨ NAME ✨

dma_alloc_from_dev_coherent — allocate memory from device coherent pool 💅

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✨ SYNOPSIS ✨

int dma_alloc_from_dev_coherent (struct device *dev , ssize_t size ,
dma_addr_t *dma_handle , void **ret );

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🌸 ARGUMENTS 🌸

• dev — the device from which we allocate memory. like, this is the main character here, the device we're pulling memory out of 🎀
• size — size of requested memory area. how much you askin' for, bestie 📏
• dma_handle — this will be filled with the correct dma handle. it's an output, so it gets filled in for you, you don't fill it ✨
• ret — this pointer will be filled with the virtual address to allocated area. again: output param, the function does the work, you just receive the virtual address of the allocated area 🦋

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💜 DESCRIPTION 💜

okay so the rules here: this function should only be called from per-arch dma_alloc_coherent. it's there to support allocation from per-device coherent memory pools. that's the whole vibe, iykyk.

now the return value, and this is important so listen up 🔥:

• it returns 0 if dma_alloc_coherent should continue with allocating from generic memory areas.
• it returns !0 (that's "not zero", bestie) if dma_alloc_coherent should return ret.

like, the return value is literally a vibe check that tells the caller whether to keep going or to bail with ret. periodt 💅

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🦋 SEE ALSO 🦋

• Kernel file ./kernel/dma/coherent.c
• dma_release_from_dev_coherent(9)
• dma_mmap_from_dev_coherent(9)

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and that's the whole page, bestie, you ate that 🍓. this lil gem lives in ./kernel/dma and it's dated October 2026 — go forth and allocate responsibly, mwah 💖🧚‍♀️