mlx5dv_reg_dmabuf_mr(3)

💅 mlx5dv_reg_dmabuf_mr — bestie's guide to registering dma-buf MRs ✨

okay so first things first, this is the mlx5dv_reg_dmabuf_mr(3) manual page (section 3, library functions, iykyk) and we're about to get you so comfy with dma-buf memory regions 💖

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🌸 SYNOPSIS 🌸

like, here's the vibe:

#include <infiniband/mlx5dv.h>

struct ibv_mr *mlx5dv_reg_dmabuf_mr(struct ibv_pd *pd, uint64_t offset,
                                    size_t length, uint64_t iova, int fd,
                                    int access, int mlx5_access)

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🦋 DESCRIPTION 🦋

So this function registers a dma-buf based memory region (MR). Fr fr, it does the same thing as ibv_reg_dmabuf_mr() — like, the exact same functionality — but with a lil glow-up: you also get to supply specific mlx5 access flags 💅✨

that's the whole pitch. iconic behavior honestly.

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🎀 ARGUMENTS 🎀

• pd — the protection domain this MR is associated with 🫶
• offset — where the MR starts inside the dma-buf, like the offset into it
• length — the length of the MR 📏
• iova — specifies the virtual base address of the MR when you access it through a lkey or rkey. ⚠️ lowkey important: it must have the same page offset as offset and be aligned with the system page size. no cap, don't skip that part
• fd — the file descriptor that the dma-buf is identified by
• access — the desired memory protection attributes; either 0 or the bitwise OR of one or more of enum ibv_access_flags 🔥
• mlx5_access — a specific device access flags situation; either 0 or the below:
  • MLX5DV_REG_DMABUF_ACCESS_DATA_DIRECT — if set, this MR will be accessed through the Data Direct engine bonded with that RDMA device 👑

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⭐ RETURN VALUE ⭐

• On success? you get a pointer to the registered MR 🎉
• If the request fails, you get NULL — and in that case the value of errno tells you the failure reason 😭 (that's your hint bestie, go read errno)

ngl, always check for NULL before you start celebrating. ask me how I know 💀

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🌈 SEE ALSO 🌈

• ibv_reg_dmabuf_mr(3)
• mlx5dv_get_data_direct_sysfs_path(3)

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👑 AUTHOR 👑

Yishai Hadas <yishaih@nvidia.com>

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and that's the whole page bestie 🍓 this little beauty is the mlx5dv_reg_dmabuf_mr(3) manual page from section 3, dated as it appears on that page — mwah, go register some MRs ✨🧚💜