async_xor(9)

✨ async_xor(9) ✨

okay so bestie, this is a page from the Kernel API Manual, section 9 — yes, the kernel section, we're literally in the big leagues 💅

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🌸 NAME 🌸

async_xor — the function that attempts to xor a whole set of blocks using a dma engine 🎀

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🦋 SYNOPSIS 🦋

struct dma_async_tx_descriptor * async_xor (struct page *dest , struct
page **src_list , unsigned int offset , int src_cnt , size_t len ,
struct async_submit_ctl *submit );

like, the whole thing returns a struct dma_async_tx_descriptor *, no cap ✨

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💖 ARGUMENTS 💖

• dest — the destination page, the main character of this operation 👑
• src_list — an array of source pages (yes, array, plural, we have options here)
• offset — the common src/dst offset where the transaction starts getting going 🏁
• src_cnt — how many source pages you're feeding in, count them, bestie
• len — length in bytes, fr fr
• submit — the submission / completion modifiers, the little vibe settings 🎛️

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🔥 DESCRIPTION 🔥

the honored flags are, and I quote the energy: ASYNC_TX_ACK, ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DST — iconics only 💫

so here's the tea: xor_gen always uses the dest as a source, which means you must set the ASYNC_TX_XOR_ZERO_DST flag if you do not want the dest data included in the calculation. periodt. the assumption with dma engines is that they only use the destination buffer as a source when it's explicitly specified in the source list 👀

src_list note: if the dest is also a source, it must be at index zero. no negotiating on that one 🫶 and heads up — the contents of this array will be overwritten if a scribble region is not specified 😭

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🌈 SEE ALSO 🌈

• Kernel file ./crypto/async_tx/async_xor.c 📁
• async_xor_offs(9) ⭐
• async_xor_val_offs(9) ⭐

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and that's the whole page, bestie!! 🍓 this little beauty lives in ./crypto/async_tx and it's dated October 2026 — so like, from the future, we love a timeless queen 💜🧚✨