mlx5_fpga_mem_write(9)

💜 mlx5_fpga_mem_write — bestie edition 💜

Okay so this is mlx5_fpga_mem_write, a little function from the Linux Kernel API Manual (that's the manual name, bestie, it's a whole kernel thing) and honestly? It's the "put stuff INTO the FPGA" girlie. Let's get into it 🎀

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✨ NAME ✨

mlx5_fpga_mem_write — write into the FPGA memory address space. That's it, that's the vibe 💅

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🌸 SYNOPSIS 🌸

int mlx5_fpga_mem_write (struct mlx5_fpga_device *fdev , size_t size ,
       u64 addr , void *buf , enum mlx5_fpga_access_type access_type );

Yes the spacing is a little chaotic, no we're not fixing it, she's iconic as-is 😌

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🦋 ARGUMENTS 🦋

• fdev — the FPGA device itself. The main character, the one you're writing to 🫶
• size — how big the chunk you're writing is, in bytes. Measure twice, write once, ngl.
• addr — the starting address you're writing to, in FPGA address space. This is where the magic lands ✨
• buf — the buffer holding the data you wanna write. Your lil payload 💌
• access_type — the method used for writing. Yes there's more than one way, and you get to pick 👑

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⭐ DESCRIPTION ⭐

So what it does: it writes the data from the buffer you passed to FPGA memory at the address you specified. Simple, clean, slay 💖

Now the important part, bestie, listen up: that address can point to configuration space or to DDR. Both are valid, she's flexible like that.

And here's the caveat you cannot skip — large writes may be performed internally as several non-atomic operations. So like, if you're expecting one big atomic write for a big chunk? No ma'am. It's giving "we'll get there in pieces" 💀

Also: this function may sleep, so it should not be called from atomic contexts. Deadass. Do not do it. Take her somewhere she can nap 😴

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🔥 RETURN 🔥

0 if it worked, or an error value otherwise. That's the whole story. Zero means slay, anything else means something went sideways 🙈

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🌈 SEE ALSO 🌈

The kernel file ./drivers/net/ethernet/mellanox/mlx5/core/fpga/sdk.h, plus the whole friend group:

• Innova SDK(9)
• enum mlx5_fpga_access_type(9)
• struct mlx5_fpga_dma_entry(9)
• struct mlx5_fpga_dma_buf(9)
• struct mlx5_fpga_conn_attr(9)
• mlx5_fpga_sbu_conn_create(9)
• mlx5_fpga_sbu_conn_destroy(9)
• mlx5_fpga_sbu_conn_sendmsg(9)
• mlx5_fpga_mem_read(9) — the reader sister, her counterpart 👯
• mlx5_fpga_get_sbu_caps(9)

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Lowkey reminder: no atomic contexts, bestie. She sleeps. Respect the nap 🧚

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And that's the whole page! Signing off with the source, which is ./drivers/net/ethernet/mellano..., dated October 2026 — so like, future girlie energy fr fr 🦋✨💜