RDMA_REG_READ(3)

💖 RDMA_REG_READ 💖

okay bestie, gather round, because we're about to talk about rdma_reg_read — a little function from the Librdmacm Programmer's Manual that's honestly giving backstage pass to your memory energy 🎀

✨ NAME ✨

rdma_reg_read — register data buffer(s) for remote RDMA read access.

like. you're literally signing your memory up to be read by someone else. consent first, always 💅

🌸 SYNOPSIS 🌸

#include <rdma/rdma_verbs.h>

struct ibv_mr * rdma_reg_read (struct rdma_cm_id *id, void *addr, size_t
length);

she's short, she's sweet, she returns a pointer to a memory region 🦋

🎀 ARGUMENTS 🎀

• id — a reference to a communication identifier, aka the spot where your message buffer(s) are gonna get used. think of it as the group chat your buffer is joining 💬
• addr — the address of the memory buffer(s) you're registering. yes, the actual address. like handing over your home address but for bytes 🏠
• length — the total length of the memory you're registering. how many bytes are we talking, bestie? 📏

💜 DESCRIPTION 💜

So what she does: she registers a memory buffer that a remote RDMA read operation is gonna access. no cap.

Memory buffers registered using rdma_reg_read may be targeted in an RDMA read request — which means the buffer can be specified on the remote side of an RDMA connection as the remote_addr of rdma_post_read, or any similar call. it's giving "you can point at me from across the network" ✨

🔥 RETURN VALUE 🔥

Returns a reference to the registered memory region on success 👑 or NULL on error 💀

If an error occurs, errno will be set to indicate the failure reason. so like, always check her. don't just assume. she will tell you what went wrong, but only if you look 🙈

🧚 NOTES 🧚

rdma_reg_read is used to register a data buffer that will be the target of an RDMA read operation on a queue pair associated with an rdma_cm_id.

The memory buffer is registered with the protection domain associated with the identifier. the start of the data buffer is specified through the addr parameter, and the total size of the buffer is given by length. periodt. 📐

⭐ important, bestie, do not skip this one: all data buffers should be registered before being posted as a work request. order matters, okay?

💀 and you must deregister all registered memory by calling rdma_dereg_mr. every single one. no leaving your memory registered out here in the wild, that's not the vibe.

🫶 SEE ALSO 🫶

rdma_cm(7), rdma_create_id(3), rdma_create_ep(3), rdma_reg_msgs(3), rdma_reg_write(3), ibv_reg_mr(3), ibv_dereg_mr(3), rdma_post_read(3)

and that's the whole page, bestie 💖 go register some memory responsibly, check your errno, deregister when you're done, and stay iconic ✨

this has been librdmacm, dated 2010-07-19, signing off 🎀🦋💅