efx_siena_mcdi_rpc(9)

✨ efx_siena_mcdi_rpc(9) ✨

okay so this is a page from the Kernel API Manual bestie, and it's literally about efx_siena_mcdi_rpc — issuing an MCDI command and waiting for it to finish. yes, waiting. it's giving "I'll text you back when I'm done" energy 💅

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🌸 NAME 🌸

efx_siena_mcdi_rpc — issue an MCDI command and then just… wait for completion 🫶

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🎀 SYNOPSIS 🎀

int efx_siena_mcdi_rpc (struct efx_nic *efx , unsigned int cmd , const
efx_dword_t *inbuf , size_t inlen , efx_dword_t *outbuf , size_t outlen
, size_t *outlen_actual );

like, look at all those arguments. she's high maintenance but she's worth it 💖

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🦋 ARGUMENTS 🦋

• efx — the NIC you're sending the command through. main character of this whole operation ✨
• cmd — the command type number. just a lil number that says what you want 👑
• inbuf — command parameters go here. that's the tea you're sending 🍓
• inlen — length of the command parameters in bytes. must be a multiple of 4 and no greater than MCDI_CTL_SDU_LEN_MAX_V1. no cap, those are the rules 😤
• outbuf — the response buffer. may be NULL if outlen is 0. slay, optional queen 🙈
• outlen — length of the response buffer, in bytes. if the actual response is longer than outlen & ~3, it gets truncated to that length. yes it will just chop it, don't come for her 💀
• outlen_actual — pointer through which the actual response length gets returned. may be NULL if you literally don't need it 💜

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🌈 DESCRIPTION 🌈

this function may sleep, so bestie you gotta call it in an appropriate context. not me warning you about context — it's important, iykyk 😭

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🔥 RETURN 🔥

so it returns a negative error code, or zero if it's all good ✨

and like, the error code can come from two places:

• the MCDI response — in which case the response will still be copied to outbuf and *outlen_actual will be set accordingly 🫶
• a failure to communicate with the MC — in which case *outlen_actual will be set to zero. gone. zeroed. nothing there 💀

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⭐ SEE ALSO ⭐

• Kernel file ./drivers/net/ethernet/sfc/siena/mcdi.c
• efx_siena_mcdi_rpc_async(9) — the not-waiting version, go read it too 🧚

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and that's the whole vibe, bestie 💖 this icon lives in ./drivers/net/ethernet/sfc/siena, dated October 2026 — see you in the kernel source, mwah 🎀