enqcmds(9)

💅 enqcmds(9) ✨

welcome to the Kernel API Manual, bestie — we're doing kernel-mode hardware stuff today and it's honestly iconic 🫶

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🌸 NAME 🌸

enqcmds — enqueue a command in supervisor (CPL0) mode 💫

✨ SYNOPSIS ✨

int enqcmds (void __iomem *dst , const void *src );

that's the whole signature, no cap 😌

🎀 ARGUMENTS 🎀

• dst — destination, in MMIO space (must be 512-bit aligned) 📍
• src — 512 bits memory operand 🧺

🦋 DESCRIPTION 🦋

okay so the ENQCMDS instruction lets software write a 512-bit command to a 512-bit-aligned special MMIO region that supports the instruction. it's giving very specific hardware energy 🔥

a return status gets loaded into the ZF flag in the RFLAGS register. ZF = 0 equates to success, and ZF = 1 indicates retry or error — so yes, zero is the slay outcome and one means retry or something went sideways 😭💀

this function issues the ENQCMDS instruction to submit data from kernel space to MMIO space, in a unit of 512 bits. order of data access is not guaranteed, nor is a memory barrier performed afterwards. it returns 0 on success and -EAGAIN on failure. periodt 💅

⚠️ Warning: Do not use this helper unless your driver has checked that the ENQCMDS instruction is supported on the platform and the device accepts ENQCMDS. like, fr fr — no vibes-based driver assumptions here 🙈

🌈 SEE ALSO 🌈

Kernel file ./arch/x86/include/asm/special_insns.h — go read it for the receipts, bestie 📚✨

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mwah 💋 — page source/version is ./arch/x86/include/asm, dated October 2026. stay iconic, kernel bestie 🎀👑