iosubmit_cmds512(9)

💅 iosubmit_cmds512(9) — your MMIO bestie has entered the chat

okay so this little icon lives in the Kernel API Manual, and she does exactly one job: copy data to a single MMIO location, in 512-bit units. no cap, that’s the whole vibe ✨

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🌸 NAME 🌸

iosubmit_cmds512 — copy data to single MMIO location, in 512-bit units 🎀

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🦋 SYNOPSIS 🦋

void iosubmit_cmds512 (void __iomem *dst , const void *src , size_t
       count );

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🎀 ARGUMENTS 🎀

• dst — bestie, this is the destination, and it lives in MMIO space. it must be 512-bit aligned 👑
• src — the source. that’s where the data is coming from 💖
• count — the number of 512-bit quantities to submit. yes, quantities. she’s counting in 512-bit units 🧚

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🔥 DESCRIPTION 🔥

so basically, this helper submits data from kernel space to MMIO space, in units of 512 bits at a time. it’s giving “bulk transfer but make it MMIO” 💅

but listen: order of access is not guaranteed, and no memory barrier is performed afterwards. so don’t go assuming things happen in a cute little sequence or that everything is synced up after. it is not that girl 😭

⚠️ Warning, bestie: Do not use this helper unless your driver has checked that the CPU instruction is supported on the platform. fr fr, this is not a “try it and see” situation 💀

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🌈 SEE ALSO 🌈

• Kernel file ./tools/arch/x86/include/asm/io.h — go read it, iykyk 🫶

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okay that’s the tea from ./tools/arch/x86/include/asm, dated October 2026 💖✨ slay responsibly, bestie 🎀