| .\" -*- nroff -*- |
| .\" Licensed under the OpenIB.org BSD license (FreeBSD Variant) - See COPYING.md |
| .\" |
| .TH IBV_REG_MR 3 2006-10-31 libibverbs "Libibverbs Programmer's Manual" |
| .SH "NAME" |
| ibv_reg_mr, ibv_reg_mr_iova, ibv_reg_dmabuf_mr, ibv_dereg_mr \- register or deregister a memory region (MR) |
| .SH "SYNOPSIS" |
| .nf |
| .B #include <infiniband/verbs.h> |
| .sp |
| .BI "struct ibv_mr *ibv_reg_mr(struct ibv_pd " "*pd" ", void " "*addr" , |
| .BI " size_t " "length" ", int " "access" ); |
| .sp |
| .BI "struct ibv_mr *ibv_reg_mr_iova(struct ibv_pd " "*pd" ", void " "*addr" , |
| .BI " size_t " "length" ", uint64_t " "hca_va" , |
| .BI " int " "access" ); |
| .sp |
| .BI "struct ibv_mr *ibv_reg_dmabuf_mr(struct ibv_pd " "*pd" ", uint64_t " "offset" , |
| .BI " size_t " "length" ", uint64_t " "iova" , |
| .BI " int " "fd" ", int " "access" ); |
| .sp |
| .BI "int ibv_dereg_mr(struct ibv_mr " "*mr" ); |
| .fi |
| .SH "DESCRIPTION" |
| .B ibv_reg_mr() |
| registers a memory region (MR) associated with the protection domain |
| .I pd\fR. |
| The MR's starting address is |
| .I addr |
| and its size is |
| .I length\fR. |
| The argument |
| .I access |
| describes the desired memory protection attributes; it is either 0 or the bitwise OR of one or more of the following flags: |
| .PP |
| .TP |
| .B IBV_ACCESS_LOCAL_WRITE \fR |
| Enable Local Write Access |
| .TP |
| .B IBV_ACCESS_REMOTE_WRITE \fR |
| Enable Remote Write Access |
| .TP |
| .B IBV_ACCESS_REMOTE_READ\fR |
| Enable Remote Read Access |
| .TP |
| .B IBV_ACCESS_REMOTE_ATOMIC\fR |
| Enable Remote Atomic Operation Access (if supported) |
| .TP |
| .B IBV_ACCESS_FLUSH_GLOBAL\fR |
| Enable Remote Flush Operation with global visibility placement type (if supported) |
| .TP |
| .B IBV_ACCESS_FLUSH_PERSISTENT\fR |
| Enable Remote Flush Operation with persistence placement type (if supported) |
| .TP |
| .B IBV_ACCESS_MW_BIND\fR |
| Enable Memory Window Binding |
| .TP |
| .B IBV_ACCESS_ZERO_BASED\fR |
| Use byte offset from beginning of MR to access this MR, instead of a pointer address |
| .TP |
| .B IBV_ACCESS_ON_DEMAND\fR |
| Create an on-demand paging MR |
| .TP |
| .B IBV_ACCESS_HUGETLB\fR |
| Huge pages are guaranteed to be used for this MR, applicable with IBV_ACCESS_ON_DEMAND in explicit mode only |
| .TP |
| .B IBV_ACCESS_RELAXED_ORDERING\fR |
| This setting allows the NIC to relax the order that data is transferred between the |
| network and the target memory region. Relaxed ordering allows network initiated |
| writes (such as incoming message send or RDMA write operations) to reach memory |
| in an arbitrary order. This can improve the performance of some applications. |
| However, relaxed ordering has the following impact: RDMA write-after-write message |
| order is no longer guaranteed. (Send messages will still match posted receive buffers |
| in order.) Back-to-back network writes that target the same memory region |
| leave the region in an unknown state. Relaxed ordering does not change completion |
| semantics, such as data visibility. That is, a completion still ensures that all |
| data is visible, including data from prior transfers. Relaxed ordered operations |
| will also not bypass atomic operations. |
| .PP |
| If |
| .B IBV_ACCESS_REMOTE_WRITE |
| or |
| .B IBV_ACCESS_REMOTE_ATOMIC |
| is set, then |
| .B IBV_ACCESS_LOCAL_WRITE |
| must be set too. |
| .PP |
| Local read access is always enabled for the MR. |
| .PP |
| To create an implicit ODP MR, IBV_ACCESS_ON_DEMAND should be set, addr should be 0 and length should be SIZE_MAX. |
| .PP |
| If |
| .B IBV_ACCESS_HUGETLB |
| is set, then application awares that for this MR all pages are huge and must promise it will never do anything to break huge pages. |
| .PP |
| .B ibv_reg_mr_iova() |
| ibv_reg_mr_iova is the same as the normal reg_mr, except that the user is |
| allowed to specify the virtual base address of the MR when accessed through |
| a lkey or rkey. The offset in the memory region is computed as 'addr + |
| (iova - hca_va)'. Specifying 0 for hca_va has the same effect as |
| IBV_ACCESS_ZERO_BASED. |
| .PP |
| .B ibv_reg_dmabuf_mr() |
| registers a dma-buf based memory region (MR) associated with the protection domain |
| .I pd\fR. |
| The MR starts at |
| .I offset |
| of the dma-buf and its size is |
| .I length\fR. |
| The dma-buf is identified by the file descriptor |
| .I fd\fR. |
| The argument |
| .I iova |
| specifies the virtual base address of the MR when accessed through a lkey or rkey. |
| It must have the same page offset as |
| .I offset\fR. |
| The argument |
| .I access |
| describes the desired memory protection attributes; it is similar to the ibv_reg_mr case except that only the following flags are supported: |
| .B IBV_ACCESS_LOCAL_WRITE, IBV_ACCESS_REMOTE_WRITE, IBV_ACCESS_REMOTE_READ, IBV_ACCESS_REMOTE_ATOMIC, IBV_ACCESS_RELAXED_ORDERING. |
| .PP |
| .B ibv_dereg_mr() |
| deregisters the MR |
| .I mr\fR. |
| .SH "RETURN VALUE" |
| .B ibv_reg_mr() / ibv_reg_mr_iova() / ibv_reg_dmabuf_mr() |
| returns a pointer to the registered MR, or NULL if the request fails. |
| The local key (\fBL_Key\fR) field |
| .B lkey |
| is used as the lkey field of struct ibv_sge when posting buffers with |
| ibv_post_* verbs, and the the remote key (\fBR_Key\fR) |
| field |
| .B rkey |
| is used by remote processes to perform Atomic and RDMA operations. The remote process places this |
| .B rkey |
| as the rkey field of struct ibv_send_wr passed to the ibv_post_send function. |
| .PP |
| .B ibv_dereg_mr() |
| returns 0 on success, or the value of errno on failure (which indicates the failure reason). |
| .SH "NOTES" |
| .B ibv_dereg_mr() |
| fails if any memory window is still bound to this MR. |
| .SH "SEE ALSO" |
| .BR ibv_alloc_pd (3), |
| .BR ibv_post_send (3), |
| .BR ibv_post_recv (3), |
| .BR ibv_post_srq_recv (3) |
| .SH "AUTHORS" |
| .TP |
| Dotan Barak <dotanba@gmail.com> |
