IBV_REREG_MR(3)

🌸 NAME 🌸

ibv_rereg_mr — re-register a memory region (MR). This is from the Libibverbs Programmer’s Manual, bestie, and yes, ibv_rereg_mr(3) is literally the glow-up page for MRs 💅

✨ SYNOPSIS ✨

#include <infiniband/verbs.h>

int ibv_rereg_mr(struct ibv_mr *mr,
                 int flags,
                 struct ibv_pd *pd,
                 void *addr,
                 size_t length,
                 int access);

💅 DESCRIPTION 💅

okay so ibv_rereg_mr() modifies the attributes of an existing memory region (MR), mr. Conceptually, this call performs the functions deregister memory region followed by register memory region — it’s giving makeover arc ✨ Where possible, resources are reused instead of deallocated and reallocated, which is highkey iconic.

flags is a bit-mask used to indicate which of the following properties of the memory region are being modified. flags should be a combination (bit field) of:

• IBV_REREG_MR_CHANGE_TRANSLATION — Change translation (location and length)
• IBV_REREG_MR_CHANGE_PD — Change protection domain
• IBV_REREG_MR_CHANGE_ACCESS — Change access flags

When IBV_REREG_MR_CHANGE_PD is used, pd represents the new PD this MR should be registered to.

When IBV_REREG_MR_CHANGE_TRANSLATION is used, addr represents the virtual address (user-space pointer) of the new MR, while length represents its length.

The access and other flags are represented in the field access. This field describes the desired memory protection attributes; it is either 0 or the bitwise OR of one or more of ibv_access_flags.

🫶 RETURN VALUE 🫶

ibv_rereg_mr() returns 0 on success, otherwise an error has occurred, and enum ibv_rereg_mr_err_code represents the error as of below. vibe check time 👑

• IBV_REREG_MR_ERR_INPUT — Old MR is valid, an input error was detected by libibverbs.
• IBV_REREG_MR_ERR_DONT_FORK_NEW — Old MR is valid, failed via don’t fork on new address range.
• IBV_REREG_MR_ERR_DO_FORK_OLD — New MR is valid, failed via do fork on old address range.
• IBV_REREG_MR_ERR_CMD — MR shouldn’t be used, command error.
• IBV_REREG_MR_ERR_CMD_AND_DO_FORK_NEW — MR shouldn’t be used, command error, invalid fork state on new address range.

😭 NOTES 😭

Even on a failure, the user still needs to call ibv_dereg_mr on this MR. not me forgetting the cleanup bestie 😭

👀 SEE ALSO 👀

ibv_dereg_mr(3), ibv_reg_mr(3) — go read these too, iykyk 🦋

🎀 AUTHORS 🎀

Matan Barak <matanb@mellanox.com>, Yishai Hadas <yishaih@mellanox.com>

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xoxo, source/version + date: libibverbs, 2016-03-13 — mwah 💋✨