/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil -*- */
/*
 * Copyright (c) 2004-2011 The Trustees of Indiana University and Indiana
 *                         University Research and Technology
 *                         Corporation.  All rights reserved.
 * Copyright (c) 2004-2022 The University of Tennessee and The University
 *                         of Tennessee Research Foundation.  All rights
 *                         reserved.
 * Copyright (c) 2004-2007 High Performance Computing Center Stuttgart,
 *                         University of Stuttgart.  All rights reserved.
 * Copyright (c) 2004-2005 The Regents of the University of California.
 *                         All rights reserved.
 * Copyright (c) 2006-2007 Voltaire. All rights reserved.
 * Copyright (c) 2009-2012 Cisco Systems, Inc.  All rights reserved.
 * Copyright (c) 2010-2017 Los Alamos National Security, LLC. All rights
 *                         reserved.
 * Copyright (c) 2012-2015 NVIDIA Corporation.  All rights reserved.
 * Copyright (c) 2012      Oracle and/or its affiliates.  All rights reserved.
 * Copyright (c) 2014-2017 Research Organization for Information Science
 *                         and Technology (RIST). All rights reserved.
 * Copyright (c) 2015-2019 Intel, Inc.  All rights reserved.
 * Copyright (c) 2022      Amazon.com, Inc. or its affiliates.  All Rights reserved.
 * Copyright (c) 2022      IBM Corporation. All rights reserved
 * Copyright (c) 2023      Triad National Security, LLC. All rights
 *                         reserved.
 * $COPYRIGHT$
 *
 * Additional copyrights may follow
 *
 * $HEADER$
 */

#include "opal_config.h"

#include <sys/stat.h>
#include <sys/types.h>
#ifdef HAVE_FCNTL_H
#    include <fcntl.h>
#endif /* HAVE_FCNTL_H */
#include <errno.h>
#ifdef HAVE_SYS_MMAN_H
#    include <sys/mman.h>
#endif /* HAVE_SYS_MMAN_H */

#ifdef OPAL_BTL_SM_CMA_NEED_SYSCALL_DEFS
#    include "opal/sys/cma.h"
#endif /* OPAL_BTL_SM_CMA_NEED_SYSCALL_DEFS */

#include "opal/class/opal_bitmap.h"
#include "opal/datatype/opal_convertor.h"
#include "opal/mca/btl/btl.h"
#include "opal/mca/hwloc/base/base.h"
#include "opal/mca/pmix/base/base.h"
#include "opal/mca/shmem/base/base.h"
#include "opal/mca/shmem/shmem.h"
#include "opal/sys/atomic.h"
#include "opal/util/output.h"
#include "opal/util/printf.h"
#include "opal/util/show_help.h"

#include "opal/mca/common/sm/common_sm_mpool.h"

#include "opal/mca/accelerator/accelerator.h"
#include "opal/mca/accelerator/base/base.h"
#include "opal/mca/mpool/base/base.h"
#include "opal/mca/rcache/base/base.h"

#include "btl_smcuda.h"
#include "btl_smcuda_endpoint.h"
#include "btl_smcuda_fifo.h"
#include "btl_smcuda_frag.h"
#include "btl_smcuda_accelerator.h"


#include "opal/include/opal/opal_cuda.h"

static struct mca_btl_base_registration_handle_t *
mca_btl_smcuda_register_mem(struct mca_btl_base_module_t *btl,
                            struct mca_btl_base_endpoint_t *endpoint, void *base, size_t size,
                            uint32_t flags);

static int mca_btl_smcuda_deregister_mem(struct mca_btl_base_module_t *btl,
                                         struct mca_btl_base_registration_handle_t *handle);

mca_btl_smcuda_t mca_btl_smcuda = {.super = {
                                       .btl_component = &mca_btl_smcuda_component.super,
                                       .btl_add_procs = mca_btl_smcuda_add_procs,
                                       .btl_del_procs = mca_btl_smcuda_del_procs,
                                       .btl_finalize = mca_btl_smcuda_finalize,
                                       .btl_alloc = mca_btl_smcuda_alloc,
                                       .btl_free = mca_btl_smcuda_free,
                                       .btl_prepare_src = mca_btl_smcuda_prepare_src,
                                       .btl_register_mem = mca_btl_smcuda_register_mem,
                                       .btl_deregister_mem = mca_btl_smcuda_deregister_mem,
                                       .btl_send = mca_btl_smcuda_send,
                                       .btl_sendi = mca_btl_smcuda_sendi,
                                       .btl_dump = mca_btl_smcuda_dump,
                                       .btl_register_error = mca_btl_smcuda_register_error_cb,
                                   }};

static void mca_btl_smcuda_send_cuda_ipc_request(struct mca_btl_base_module_t *btl,
                                                 struct mca_btl_base_endpoint_t *endpoint);
/*
 * calculate offset of an address from the beginning of a shared memory segment
 */
#define ADDR2OFFSET(ADDR, BASE) ((char *) (ADDR) - (char *) (BASE))

/*
 * calculate an absolute address in a local address space given an offset and
 * a base address of a shared memory segment
 */
#define OFFSET2ADDR(OFFSET, BASE) ((ptrdiff_t)(OFFSET) + (char *) (BASE))

static void *mpool_calloc(size_t nmemb, size_t size)
{
    void *buf;
    size_t bsize = nmemb * size;
    mca_mpool_base_module_t *mpool = mca_btl_smcuda_component.sm_mpool;

    buf = mpool->mpool_alloc(mpool, bsize, opal_cache_line_size, 0);

    if (NULL == buf)
        return NULL;

    memset(buf, 0, bsize);
    return buf;
}

static int setup_mpool_base_resources(mca_btl_smcuda_component_t *comp_ptr,
                                      mca_common_sm_mpool_resources_t *out_res)
{
    int rc = OPAL_SUCCESS;
    int fd = -1;
    ssize_t bread = 0;

    if (-1 == (fd = open(comp_ptr->sm_mpool_rndv_file_name, O_RDONLY))) {
        int err = errno;
        opal_show_help("help-mpi-btl-smcuda.txt", "sys call fail", true, "open(2)", strerror(err),
                       err);
        rc = OPAL_ERR_IN_ERRNO;
        goto out;
    }
    if ((ssize_t) sizeof(opal_shmem_ds_t)
        != (bread = read(fd, &out_res->bs_meta_buf, sizeof(opal_shmem_ds_t)))) {
        opal_output(0,
                    "setup_mpool_base_resources: "
                    "Read inconsistency -- read: %lu, but expected: %lu!\n",
                    (unsigned long) bread, (unsigned long) sizeof(opal_shmem_ds_t));
        rc = OPAL_ERROR;
        goto out;
    }
    if ((ssize_t) sizeof(out_res->size) != (bread = read(fd, &out_res->size, sizeof(size_t)))) {
        opal_output(0,
                    "setup_mpool_base_resources: "
                    "Read inconsistency -- read: %lu, but expected: %lu!\n",
                    (unsigned long) bread, (unsigned long) sizeof(opal_shmem_ds_t));
        rc = OPAL_ERROR;
        goto out;
    }

out:
    if (-1 != fd) {
        (void) close(fd);
    }
    return rc;
}

static int sm_segment_attach(mca_btl_smcuda_component_t *comp_ptr)
{
    int rc = OPAL_SUCCESS;
    int fd = -1;
    ssize_t bread = 0;
    opal_shmem_ds_t *tmp_shmem_ds = calloc(1, sizeof(*tmp_shmem_ds));

    if (NULL == tmp_shmem_ds) {
        return OPAL_ERR_OUT_OF_RESOURCE;
    }
    if (-1 == (fd = open(comp_ptr->sm_rndv_file_name, O_RDONLY))) {
        int err = errno;
        opal_show_help("help-mpi-btl-smcuda.txt", "sys call fail", true, "open(2)", strerror(err),
                       err);
        rc = OPAL_ERR_IN_ERRNO;
        goto out;
    }
    if ((ssize_t) sizeof(opal_shmem_ds_t)
        != (bread = read(fd, tmp_shmem_ds, sizeof(opal_shmem_ds_t)))) {
        opal_output(0,
                    "sm_segment_attach: "
                    "Read inconsistency -- read: %lu, but expected: %lu!\n",
                    (unsigned long) bread, (unsigned long) sizeof(opal_shmem_ds_t));
        rc = OPAL_ERROR;
        goto out;
    }
    if (NULL
        == (comp_ptr->sm_seg = mca_common_sm_module_attach(tmp_shmem_ds,
                                                           sizeof(mca_common_sm_seg_header_t),
                                                           opal_cache_line_size))) {
        /* don't have to detach here, because module_attach cleans up after
         * itself on failure. */
        opal_output(0, "sm_segment_attach: "
                       "mca_common_sm_module_attach failure!\n");
        rc = OPAL_ERROR;
    }

out:
    if (-1 != fd) {
        (void) close(fd);
    }
    if (tmp_shmem_ds) {
        free(tmp_shmem_ds);
    }
    return rc;
}

static int smcuda_btl_first_time_init(mca_btl_smcuda_t *smcuda_btl, int32_t my_smp_rank, int n)
{
    size_t length, length_payload;
    sm_fifo_t *my_fifos;
    int my_mem_node, num_mem_nodes, i, rc;
    mca_common_sm_mpool_resources_t *res = NULL;
    mca_btl_smcuda_component_t *m = &mca_btl_smcuda_component;
    char *loc, *mynuma;
    opal_process_name_t wildcard_rank;

    /* Assume we don't have hwloc support and fill in dummy info */
    mca_btl_smcuda_component.mem_node = my_mem_node = 0;
    mca_btl_smcuda_component.num_mem_nodes = num_mem_nodes = 1;

    /* see if we were given a topology signature */
    wildcard_rank.jobid = OPAL_PROC_MY_NAME.jobid;
    wildcard_rank.vpid = OPAL_VPID_WILDCARD;
    OPAL_MODEX_RECV_VALUE_OPTIONAL(rc, PMIX_TOPOLOGY_SIGNATURE, &wildcard_rank, &loc, PMIX_STRING);
    if (OPAL_SUCCESS == rc) {
        /* the number of NUMA nodes is right at the front */
        mca_btl_smcuda_component.num_mem_nodes = num_mem_nodes = strtoul(loc, NULL, 10);
        free(loc);
    } else {
        /* If we have hwloc support, then get accurate information */
        loc = NULL;
        if (OPAL_SUCCESS == opal_hwloc_base_get_topology()) {
            i = opal_hwloc_base_get_nbobjs_by_type(opal_hwloc_topology, HWLOC_OBJ_NODE, 0,
                                                   OPAL_HWLOC_AVAILABLE);

            /* JMS This tells me how many numa nodes are *available*,
               but it's not how many are being used *by this job*.
               Note that this is the value we've previously used (from
               the previous carto-based implementation), but it really
               should be improved to be how many NUMA nodes are being
               used *in this job*. */
            mca_btl_smcuda_component.num_mem_nodes = num_mem_nodes = i;
        }
    }
    /* see if we were given our location */
    OPAL_MODEX_RECV_VALUE_OPTIONAL(rc, PMIX_LOCALITY_STRING, &OPAL_PROC_MY_NAME, &loc, PMIX_STRING);
    if (OPAL_SUCCESS == rc) {
        if (NULL == loc) {
            mca_btl_smcuda_component.mem_node = my_mem_node = -1;
        } else {
            /* get our NUMA location */
            mynuma = opal_hwloc_base_get_location(loc, HWLOC_OBJ_NODE, 0);
            if (NULL == mynuma || NULL != strchr(mynuma, ',') || NULL != strchr(mynuma, '-')) {
                /* we either have no idea what NUMA we are on, or we
                 * are on multiple NUMA nodes */
                mca_btl_smcuda_component.mem_node = my_mem_node = -1;
            } else {
                /* we are bound to a single NUMA node */
                my_mem_node = strtoul(mynuma, NULL, 10);
                mca_btl_smcuda_component.mem_node = my_mem_node;
            }
            if (NULL != mynuma) {
                free(mynuma);
            }
            free(loc);
        }
    } else {
        /* If we have hwloc support, then get accurate information */
        if (OPAL_SUCCESS == opal_hwloc_base_get_topology() && num_mem_nodes > 0
            && NULL != opal_process_info.cpuset) {
            int numa = 0, w;
            unsigned n_bound = 0;
            hwloc_obj_t obj;

            /* count the number of NUMA nodes to which we are bound */
            for (w = 0; w < i; w++) {
                if (NULL
                    == (obj = opal_hwloc_base_get_obj_by_type(opal_hwloc_topology, HWLOC_OBJ_NODE,
                                                              0, w, OPAL_HWLOC_AVAILABLE))) {
                    continue;
                }
                /* see if we intersect with that NUMA node's cpus */
                if (hwloc_bitmap_intersects(obj->cpuset, opal_hwloc_my_cpuset)) {
                    n_bound++;
                    numa = w;
                }
            }
            /* if we are located on more than one NUMA, or we didn't find
             * a NUMA we are on, then not much we can do
             */
            if (1 == n_bound) {
                mca_btl_smcuda_component.mem_node = my_mem_node = numa;
            } else {
                mca_btl_smcuda_component.mem_node = my_mem_node = -1;
            }
        }
    }

    if (NULL == (res = calloc(1, sizeof(*res)))) {
        return OPAL_ERR_OUT_OF_RESOURCE;
    }

    /* lookup shared memory pool */
    mca_btl_smcuda_component.sm_mpools = (mca_mpool_base_module_t **)
        calloc(num_mem_nodes, sizeof(mca_mpool_base_module_t *));

    /* Disable memory binding, because each MPI process will claim pages in the
     * mpool for their local NUMA node */
    res->mem_node = -1;
    res->allocator = mca_btl_smcuda_component.allocator;

    if (OPAL_SUCCESS != (rc = setup_mpool_base_resources(m, res))) {
        free(res);
        return rc;
    }
    /* now that res is fully populated, create the thing */
    mca_btl_smcuda_component.sm_mpools[0] = opal_btl_smcuda_common_sm_mpool_create(res);
    /* Sanity check to ensure that we found it */
    if (NULL == mca_btl_smcuda_component.sm_mpools[0]) {
        free(res);
        return OPAL_ERR_OUT_OF_RESOURCE;
    }

    mca_btl_smcuda_component.sm_mpool = mca_btl_smcuda_component.sm_mpools[0];

    mca_btl_smcuda_component.sm_mpool_base = mca_btl_smcuda_component.sm_mpools[0]->mpool_base(
        mca_btl_smcuda_component.sm_mpools[0]);

    /* create a list of peers */
    mca_btl_smcuda_component.sm_peers = (struct mca_btl_base_endpoint_t **)
        calloc(n, sizeof(struct mca_btl_base_endpoint_t *));
    if (NULL == mca_btl_smcuda_component.sm_peers) {
        free(res);
        return OPAL_ERR_OUT_OF_RESOURCE;
    }

    /* remember that node rank zero is already attached */
    if (0 != my_smp_rank) {
        if (OPAL_SUCCESS != (rc = sm_segment_attach(m))) {
            free(res);
            return rc;
        }
    }
    /* Register the entire shared memory region with the CUDA library which will
     * force it to be pinned.  This approach was chosen as there is no way for this
     * local process to know which parts of the memory are being utilized by a
     * remote process. */
    opal_output_verbose(10, opal_btl_base_framework.framework_output,
                        "btl:smcuda: CUDA cuMemHostRegister address=%p, size=%d",
                        mca_btl_smcuda_component.sm_mpool_base, (int) res->size);
    if (0 == strcmp(opal_accelerator_base_selected_component.base_version.mca_component_name, "cuda")) {
        rc = opal_accelerator.host_register(MCA_ACCELERATOR_NO_DEVICE_ID, mca_btl_smcuda_component.sm_mpool_base, res->size); 
        if (OPAL_UNLIKELY(OPAL_SUCCESS != rc)) {
            /* If registering the memory fails, print a message and continue.
             * This is not a fatal error. */
            opal_output_verbose(10, opal_btl_base_framework.framework_output,
                                "btl:smcuda: CUDA cuMemHostRegister failed");
        }
    }

    /* Create a local memory pool that sends handles to the remote
     * side.  Note that the res argument is not really used, but
     * needed to satisfy function signature. */
    mca_rcache_base_resources_t rcache_res;
    smcuda_btl->rcache = mca_rcache_base_module_create("gpusm", smcuda_btl, &rcache_res);
    if (NULL == smcuda_btl->rcache) {
        return OPAL_ERR_OUT_OF_RESOURCE;
    }

    /* it is now safe to free the mpool resources */
    free(res);

    /* check to make sure number of local procs is within the
     * specified limits */
    if (mca_btl_smcuda_component.sm_max_procs > 0
        && mca_btl_smcuda_component.num_smp_procs + n > mca_btl_smcuda_component.sm_max_procs) {
        return OPAL_ERROR;
    }

    mca_btl_smcuda_component.shm_fifo = (volatile sm_fifo_t **)
                                            mca_btl_smcuda_component.sm_seg->module_data_addr;
    mca_btl_smcuda_component.shm_bases = (char **) (mca_btl_smcuda_component.shm_fifo + n);
    mca_btl_smcuda_component.shm_mem_nodes = (uint16_t *) (mca_btl_smcuda_component.shm_bases + n);

    /* set the base of the shared memory segment */
    mca_btl_smcuda_component.shm_bases[mca_btl_smcuda_component.my_smp_rank]
        = (char *) mca_btl_smcuda_component.sm_mpool_base;
    mca_btl_smcuda_component.shm_mem_nodes[mca_btl_smcuda_component.my_smp_rank] = (uint16_t)
        my_mem_node;

    /* initialize the array of fifo's "owned" by this process */
    if (NULL == (my_fifos = (sm_fifo_t *) mpool_calloc(FIFO_MAP_NUM(n), sizeof(sm_fifo_t))))
        return OPAL_ERR_OUT_OF_RESOURCE;

    mca_btl_smcuda_component.shm_fifo[mca_btl_smcuda_component.my_smp_rank] = my_fifos;

    /* cache the pointer to the 2d fifo array.  These addresses
     * are valid in the current process space */
    mca_btl_smcuda_component.fifo = (sm_fifo_t **) malloc(sizeof(sm_fifo_t *) * n);

    if (NULL == mca_btl_smcuda_component.fifo)
        return OPAL_ERR_OUT_OF_RESOURCE;

    mca_btl_smcuda_component.fifo[mca_btl_smcuda_component.my_smp_rank] = my_fifos;

    mca_btl_smcuda_component.mem_nodes = (uint16_t *) malloc(sizeof(uint16_t) * n);
    if (NULL == mca_btl_smcuda_component.mem_nodes)
        return OPAL_ERR_OUT_OF_RESOURCE;

    /* initialize fragment descriptor free lists */

    /* allocation will be for the fragment descriptor and payload buffer */
    length = sizeof(mca_btl_smcuda_frag1_t);
    length_payload = sizeof(mca_btl_smcuda_hdr_t) + mca_btl_smcuda_component.eager_limit;
    i = opal_free_list_init(&mca_btl_smcuda_component.sm_frags_eager, length, opal_cache_line_size,
                            OBJ_CLASS(mca_btl_smcuda_frag1_t), length_payload, opal_cache_line_size,
                            mca_btl_smcuda_component.sm_free_list_num,
                            mca_btl_smcuda_component.sm_free_list_max,
                            mca_btl_smcuda_component.sm_free_list_inc,
                            mca_btl_smcuda_component.sm_mpool, 0, NULL, NULL, NULL);
    if (OPAL_SUCCESS != i)
        return i;

    length = sizeof(mca_btl_smcuda_frag2_t);
    length_payload = sizeof(mca_btl_smcuda_hdr_t) + mca_btl_smcuda_component.max_frag_size;
    i = opal_free_list_init(&mca_btl_smcuda_component.sm_frags_max, length, opal_cache_line_size,
                            OBJ_CLASS(mca_btl_smcuda_frag2_t), length_payload, opal_cache_line_size,
                            mca_btl_smcuda_component.sm_free_list_num,
                            mca_btl_smcuda_component.sm_free_list_max,
                            mca_btl_smcuda_component.sm_free_list_inc,
                            mca_btl_smcuda_component.sm_mpool, 0, NULL, NULL, NULL);
    if (OPAL_SUCCESS != i)
        return i;

    i = opal_free_list_init(&mca_btl_smcuda_component.sm_frags_user, sizeof(mca_btl_smcuda_user_t),
                            opal_cache_line_size, OBJ_CLASS(mca_btl_smcuda_user_t),
                            sizeof(mca_btl_smcuda_hdr_t), opal_cache_line_size,
                            mca_btl_smcuda_component.sm_free_list_num,
                            mca_btl_smcuda_component.sm_free_list_max,
                            mca_btl_smcuda_component.sm_free_list_inc,
                            mca_btl_smcuda_component.sm_mpool, 0, NULL, NULL, NULL);
    if (OPAL_SUCCESS != i)
        return i;

    mca_btl_smcuda_component.num_outstanding_frags = 0;

    mca_btl_smcuda_component.num_pending_sends = 0;
    i = opal_free_list_init(&mca_btl_smcuda_component.pending_send_fl,
                            sizeof(btl_smcuda_pending_send_item_t), 8,
                            OBJ_CLASS(opal_free_list_item_t), 0, 0, 16, -1, 32, NULL, 0, NULL, NULL,
                            NULL);
    if (OPAL_SUCCESS != i)
        return i;

    /* set flag indicating btl has been inited */
    smcuda_btl->btl_inited = true;

    return OPAL_SUCCESS;
}

static struct mca_btl_base_endpoint_t *create_sm_endpoint(int local_proc, struct opal_proc_t *proc)
{
    struct mca_btl_base_endpoint_t *ep;

#if OPAL_ENABLE_PROGRESS_THREADS == 1
    char path[PATH_MAX];
#endif

    ep = (struct mca_btl_base_endpoint_t *) malloc(sizeof(struct mca_btl_base_endpoint_t));
    if (NULL == ep)
        return NULL;
    ep->peer_smp_rank = local_proc + mca_btl_smcuda_component.num_smp_procs;

    OBJ_CONSTRUCT(&ep->pending_sends, opal_list_t);
    OBJ_CONSTRUCT(&ep->endpoint_lock, opal_mutex_t);
#if OPAL_ENABLE_PROGRESS_THREADS == 1
    sprintf(path, "%s" OPAL_PATH_SEP "sm_fifo.%lu", opal_process_info.job_session_dir,
            (unsigned long) proc->proc_name);
    ep->fifo_fd = open(path, O_WRONLY);
    if (ep->fifo_fd < 0) {
        opal_output(0, "mca_btl_smcuda_add_procs: open(%s) failed with errno=%d\n", path, errno);
        free(ep);
        return NULL;
    }
#endif

    /* Create a remote memory pool on the endpoint. The rgpusm component
     * does not take any resources. They are filled in internally. */
    ep->rcache = mca_rcache_base_module_create("rgpusm", NULL, NULL);

    return ep;
}

int mca_btl_smcuda_add_procs(struct mca_btl_base_module_t *btl, size_t nprocs,
                             struct opal_proc_t **procs, struct mca_btl_base_endpoint_t **peers,
                             opal_bitmap_t *reachability)
{
    int return_code = OPAL_SUCCESS;
    int32_t n_local_procs = 0, proc, j, my_smp_rank = -1;
    const opal_proc_t *my_proc; /* pointer to caller's proc structure */
    mca_btl_smcuda_t *smcuda_btl;
    bool have_connected_peer = false;
    char **bases;
    /* for easy access to the mpool_sm_module */
    mca_common_sm_mpool_module_t *sm_mpool_modp = NULL;

    /* initializion */

    smcuda_btl = (mca_btl_smcuda_t *) btl;

    /* get pointer to my proc structure */
    if (NULL == (my_proc = opal_proc_local_get()))
        return OPAL_ERR_OUT_OF_RESOURCE;

    /* Get unique host identifier for each process in the list,
     * and idetify procs that are on this host.  Add procs on this
     * host to shared memory reachbility list.  Also, get number
     * of local procs in the procs list. */
    for (proc = 0; proc < (int32_t) nprocs; proc++) {
        /* check to see if this proc can be reached via shmem (i.e.,
           if they're on my local host and in my job) */
        if (procs[proc]->proc_name.jobid != my_proc->proc_name.jobid
            || !OPAL_PROC_ON_LOCAL_NODE(procs[proc]->proc_flags)) {
            peers[proc] = NULL;
            continue;
        }
        /* check to see if this is me */
        if (my_proc == procs[proc]) {
            my_smp_rank = mca_btl_smcuda_component.my_smp_rank = n_local_procs++;
            continue;
        }

        /* we have someone to talk to */
        have_connected_peer = true;

        if (!(peers[proc] = create_sm_endpoint(n_local_procs, procs[proc]))) {
            return_code = OPAL_ERROR;
            goto CLEANUP;
        }

        peers[proc]->proc_opal = procs[proc];
        peers[proc]->ipcstate = IPC_INIT;
        peers[proc]->ipctries = 0;

        n_local_procs++;

        /* add this proc to shared memory accessibility list */
        return_code = opal_bitmap_set_bit(reachability, proc);
        if (OPAL_SUCCESS != return_code)
            goto CLEANUP;
    }

    /* jump out if there's not someone we can talk to */
    if (!have_connected_peer)
        goto CLEANUP;

    /* make sure that my_smp_rank has been defined */
    if (-1 == my_smp_rank) {
        return_code = OPAL_ERROR;
        goto CLEANUP;
    }

    if (!smcuda_btl->btl_inited) {
        return_code = smcuda_btl_first_time_init(smcuda_btl, my_smp_rank,
                                                 mca_btl_smcuda_component.sm_max_procs);
        if (return_code != OPAL_SUCCESS) {
            goto CLEANUP;
        }
    }

    /* set local proc's smp rank in the peers structure for
     * rapid access and calculate reachability */
    for (proc = 0; proc < (int32_t) nprocs; proc++) {
        if (NULL == peers[proc])
            continue;
        mca_btl_smcuda_component.sm_peers[peers[proc]->peer_smp_rank] = peers[proc];
        peers[proc]->my_smp_rank = my_smp_rank;
    }

    bases = mca_btl_smcuda_component.shm_bases;
    sm_mpool_modp = (mca_common_sm_mpool_module_t *) mca_btl_smcuda_component.sm_mpool;

    /* initialize own FIFOs */
    /*
     * The receiver initializes all its FIFOs.  All components will
     * be allocated near the receiver.  Nothing will be local to
     * "the sender" since there will be many senders.
     */
    for (j = mca_btl_smcuda_component.num_smp_procs;
         j < mca_btl_smcuda_component.num_smp_procs + FIFO_MAP_NUM(n_local_procs); j++) {

        return_code = sm_fifo_init(mca_btl_smcuda_component.fifo_size,
                                   mca_btl_smcuda_component.sm_mpool,
                                   &mca_btl_smcuda_component.fifo[my_smp_rank][j],
                                   mca_btl_smcuda_component.fifo_lazy_free);
        if (return_code != OPAL_SUCCESS)
            goto CLEANUP;
    }

    opal_atomic_wmb();

    /* Sync with other local procs. Force the FIFO initialization to always
     * happens before the readers access it.
     */
    (void) opal_atomic_add_fetch_32(&mca_btl_smcuda_component.sm_seg->module_seg->seg_inited, 1);
    while (n_local_procs > mca_btl_smcuda_component.sm_seg->module_seg->seg_inited) {
        opal_progress();
        opal_atomic_rmb();
    }

    /* it is now safe to unlink the shared memory segment. only one process
     * needs to do this, so just let smp rank zero take care of it. */
    if (0 == my_smp_rank) {
        if (OPAL_SUCCESS != mca_common_sm_module_unlink(mca_btl_smcuda_component.sm_seg)) {
            /* it is "okay" if this fails at this point. we have gone this far,
             * so just warn about the failure and continue. this is probably
             * only triggered by a programming error. */
            opal_output(0, "WARNING: common_sm_module_unlink failed.\n");
        }
        /* SKG - another abstraction violation here, but I don't want to add
         * extra code in the sm mpool for further synchronization. */

        /* at this point, all processes have attached to the mpool segment. so
         * it is safe to unlink it here. */
        if (OPAL_SUCCESS != mca_common_sm_module_unlink(sm_mpool_modp->sm_common_module)) {
            opal_output(0, "WARNING: common_sm_module_unlink failed.\n");
        }
        if (-1 == unlink(mca_btl_smcuda_component.sm_mpool_rndv_file_name)) {
            opal_output(0, "WARNING: %s unlink failed.\n",
                        mca_btl_smcuda_component.sm_mpool_rndv_file_name);
        }
        if (-1 == unlink(mca_btl_smcuda_component.sm_rndv_file_name)) {
            opal_output(0, "WARNING: %s unlink failed.\n",
                        mca_btl_smcuda_component.sm_rndv_file_name);
        }
    }

    /* free up some space used by the name buffers */
    free(mca_btl_smcuda_component.sm_mpool_ctl_file_name);
    free(mca_btl_smcuda_component.sm_mpool_rndv_file_name);
    free(mca_btl_smcuda_component.sm_ctl_file_name);
    free(mca_btl_smcuda_component.sm_rndv_file_name);

    /* coordinate with other processes */
    for (j = mca_btl_smcuda_component.num_smp_procs;
         j < mca_btl_smcuda_component.num_smp_procs + n_local_procs; j++) {
        ptrdiff_t diff;

        /* spin until this element is allocated */
        /* doesn't really wait for that process... FIFO might be allocated, but not initialized */
        opal_atomic_rmb();
        while (NULL == mca_btl_smcuda_component.shm_fifo[j]) {
            opal_progress();
            opal_atomic_rmb();
        }

        /* Calculate the difference as (my_base - their_base) */
        diff = ADDR2OFFSET(bases[my_smp_rank], bases[j]);

        /* store local address of remote fifos */
        mca_btl_smcuda_component.fifo[j] = (sm_fifo_t *)
            OFFSET2ADDR(diff, mca_btl_smcuda_component.shm_fifo[j]);

        /* cache local copy of peer memory node number */
        mca_btl_smcuda_component.mem_nodes[j] = mca_btl_smcuda_component.shm_mem_nodes[j];
    }

    /* update the local smp process count */
    mca_btl_smcuda_component.num_smp_procs += n_local_procs;

    /* make sure we have enough eager fragmnents for each process */
    return_code = opal_free_list_resize_mt(&mca_btl_smcuda_component.sm_frags_eager,
                                           mca_btl_smcuda_component.num_smp_procs * 2);
    if (OPAL_SUCCESS != return_code)
        goto CLEANUP;

CLEANUP:
    return return_code;
}

int mca_btl_smcuda_del_procs(struct mca_btl_base_module_t *btl, size_t nprocs,
                             struct opal_proc_t **procs, struct mca_btl_base_endpoint_t **peers)
{
    for (size_t i = 0; i < nprocs; ++i) {
        if (peers[i]->rcache) {
            mca_rcache_base_module_destroy(peers[i]->rcache);
            peers[i]->rcache = NULL;
        }
    }

    return OPAL_SUCCESS;
}

/**
 * MCA->BTL Clean up any resources held by BTL module
 * before the module is unloaded.
 *
 * @param btl (IN)   BTL module.
 *
 * Prior to unloading a BTL module, the MCA framework will call
 * the BTL finalize method of the module. Any resources held by
 * the BTL should be released and if required the memory corresponding
 * to the BTL module freed.
 *
 */

int mca_btl_smcuda_finalize(struct mca_btl_base_module_t *btl)
{
    return OPAL_SUCCESS;
}

/*
 * Register callback function for error handling..
 */
int mca_btl_smcuda_register_error_cb(struct mca_btl_base_module_t *btl,
                                     mca_btl_base_module_error_cb_fn_t cbfunc)
{
    mca_btl_smcuda_t *smcuda_btl = (mca_btl_smcuda_t *) btl;
    smcuda_btl->error_cb = cbfunc;
    return OPAL_SUCCESS;
}

/**
 * Allocate a segment.
 *
 * @param btl (IN)      BTL module
 * @param size (IN)     Request segment size.
 */
extern mca_btl_base_descriptor_t *mca_btl_smcuda_alloc(struct mca_btl_base_module_t *btl,
                                                       struct mca_btl_base_endpoint_t *endpoint,
                                                       uint8_t order, size_t size, uint32_t flags)
{
    mca_btl_smcuda_frag_t *frag = NULL;
    if (size <= mca_btl_smcuda_component.eager_limit) {
        MCA_BTL_SMCUDA_FRAG_ALLOC_EAGER(frag);
    } else if (size <= mca_btl_smcuda_component.max_frag_size) {
        MCA_BTL_SMCUDA_FRAG_ALLOC_MAX(frag);
    }

    if (OPAL_LIKELY(frag != NULL)) {
        frag->segment.seg_len = size;
        frag->base.des_flags = flags;
    }
    return (mca_btl_base_descriptor_t *) frag;
}

/**
 * Return a segment allocated by this BTL.
 *
 * @param btl (IN)      BTL module
 * @param segment (IN)  Allocated segment.
 */
extern int mca_btl_smcuda_free(struct mca_btl_base_module_t *btl, mca_btl_base_descriptor_t *des)
{
    mca_btl_smcuda_frag_t *frag = (mca_btl_smcuda_frag_t *) des;
    MCA_BTL_SMCUDA_FRAG_RETURN(frag);

    return OPAL_SUCCESS;
}

/**
 * Pack data
 *
 * @param btl (IN)      BTL module
 */
struct mca_btl_base_descriptor_t *mca_btl_smcuda_prepare_src(
    struct mca_btl_base_module_t *btl, struct mca_btl_base_endpoint_t *endpoint,
    struct opal_convertor_t *convertor, uint8_t order, size_t reserve, size_t *size, uint32_t flags)
{
    mca_btl_smcuda_frag_t *frag;
    struct iovec iov;
    uint32_t iov_count = 1;
    size_t max_data = *size;
    int rc;

    if (reserve + max_data <= mca_btl_smcuda_component.eager_limit) {
        MCA_BTL_SMCUDA_FRAG_ALLOC_EAGER(frag);
    } else {
        MCA_BTL_SMCUDA_FRAG_ALLOC_MAX(frag);
    }
    if (OPAL_UNLIKELY(NULL == frag)) {
        return NULL;
    }

    if (OPAL_UNLIKELY(reserve + max_data > frag->size)) {
        max_data = frag->size - reserve;
    }
    iov.iov_len = max_data;
    iov.iov_base = (IOVBASE_TYPE *) (((unsigned char *) (frag->segment.seg_addr.pval)) + reserve);

    rc = opal_convertor_pack(convertor, &iov, &iov_count, &max_data);
    if (OPAL_UNLIKELY(rc < 0)) {
        MCA_BTL_SMCUDA_FRAG_RETURN(frag);
        return NULL;
    }

    frag->segment.seg_len = reserve + max_data;
    frag->base.des_segments = &frag->segment;
    frag->base.des_segment_count = 1;
    frag->base.order = MCA_BTL_NO_ORDER;
    frag->base.des_flags = flags;
    *size = max_data;
    return &frag->base;
}

#if 0
#    define MCA_BTL_SMCUDA_TOUCH_DATA_TILL_CACHELINE_BOUNDARY(sm_frag) \
        do {                                                           \
            char *_memory = (char *) (sm_frag)->segment.seg_addr.pval  \
                            + (sm_frag)->segment.seg_len;              \
            int *_intmem;                                              \
            size_t align = (intptr_t) _memory & 0xFUL;                 \
            switch (align & 0x3) {                                     \
            case 3:                                                    \
                *_memory = 0;                                          \
                _memory++;                                             \
            case 2:                                                    \
                *_memory = 0;                                          \
                _memory++;                                             \
            case 1:                                                    \
                *_memory = 0;                                          \
                _memory++;                                             \
            }                                                          \
            align >>= 2;                                               \
            _intmem = (int *) _memory;                                 \
            switch (align) {                                           \
            case 3:                                                    \
                *_intmem = 0;                                          \
                _intmem++;                                             \
            case 2:                                                    \
                *_intmem = 0;                                          \
                _intmem++;                                             \
            case 1:                                                    \
                *_intmem = 0;                                          \
                _intmem++;                                             \
            }                                                          \
        } while (0)
#else
#    define MCA_BTL_SMCUDA_TOUCH_DATA_TILL_CACHELINE_BOUNDARY(sm_frag)
#endif

#if 0
        if( OPAL_LIKELY(align > 0) ) {                                  \
            align = 0xFUL - align;                                      \
            memset( _memory, 0, align );                                \
        }

#endif

/**
 * Initiate an inline send to the peer. If failure then return a descriptor.
 *
 * @param btl (IN)      BTL module
 * @param peer (IN)     BTL peer addressing
 */
int mca_btl_smcuda_sendi(struct mca_btl_base_module_t *btl,
                         struct mca_btl_base_endpoint_t *endpoint,
                         struct opal_convertor_t *convertor, void *header, size_t header_size,
                         size_t payload_size, uint8_t order, uint32_t flags, mca_btl_base_tag_t tag,
                         mca_btl_base_descriptor_t **descriptor)
{
    size_t length = (header_size + payload_size);
    mca_btl_smcuda_frag_t *frag;
    int rc;

    if (mca_btl_smcuda_component.num_outstanding_frags * 2
        > (int) mca_btl_smcuda_component.fifo_size) {
        mca_btl_smcuda_component_progress();
    }
    /* Initiate setting up CUDA IPC support. */

    if (0 == strcmp(opal_accelerator_base_selected_component.base_version.mca_component_name, "cuda") && (IPC_INIT == endpoint->ipcstate)
        && mca_btl_smcuda_component.use_cuda_ipc) {
        mca_btl_smcuda_send_cuda_ipc_request(btl, endpoint);
    }
    /* We do not want to use this path when we have CUDA IPC support */
    if ((NULL != convertor) && (convertor->flags & CONVERTOR_ACCELERATOR) && (IPC_ACKED == endpoint->ipcstate)) {
        goto return_resource_busy;
    }

    /* this check should be unnecessary... turn into an assertion? */
    if (length < mca_btl_smcuda_component.eager_limit) {

        /* allocate a fragment, giving up if we can't get one */
        /* note that frag==NULL is equivalent to rc returning an error code */
        MCA_BTL_SMCUDA_FRAG_ALLOC_EAGER(frag);
        if (OPAL_UNLIKELY(NULL == frag)) {
            goto return_resource_busy;
        }

        /* fill in fragment fields */
        frag->segment.seg_len = length;
        frag->hdr->len = length;
        assert(0 == (flags & MCA_BTL_DES_SEND_ALWAYS_CALLBACK));
        frag->base.des_flags = flags
                               | MCA_BTL_DES_FLAGS_BTL_OWNERSHIP; /* why do any flags matter here
                                                                     other than OWNERSHIP? */
        frag->hdr->tag = tag;
        frag->endpoint = endpoint;

        /* write the match header (with MPI comm/tag/etc. info) */
        memcpy(frag->segment.seg_addr.pval, header, header_size);

        /* write the message data if there is any */
        /*
          We can add MEMCHECKER calls before and after the packing.
        */
        if (payload_size) {
            size_t max_data;
            struct iovec iov;
            uint32_t iov_count;
            /* pack the data into the supplied buffer */
            iov.iov_base = (IOVBASE_TYPE *) ((unsigned char *) frag->segment.seg_addr.pval
                                             + header_size);
            iov.iov_len = max_data = payload_size;
            iov_count = 1;

            (void) opal_convertor_pack(convertor, &iov, &iov_count, &max_data);

            assert(max_data == payload_size);
        }

        MCA_BTL_SMCUDA_TOUCH_DATA_TILL_CACHELINE_BOUNDARY(frag);

        /* write the fragment pointer to the FIFO */
        /*
         * Note that we don't care what the FIFO-write return code is.  Even if
         * the return code indicates failure, the write has still "completed" from
         * our point of view:  it has been posted to a "pending send" queue.
         */
        OPAL_THREAD_ADD_FETCH32(&mca_btl_smcuda_component.num_outstanding_frags, +1);
        MCA_BTL_SMCUDA_FIFO_WRITE(endpoint, endpoint->my_smp_rank, endpoint->peer_smp_rank,
                                  (void *) VIRTUAL2RELATIVE(frag->hdr), false, true, rc);
        (void) rc; /* this is safe to ignore as the message is requeued till success */
        return OPAL_SUCCESS;
    }

  return_resource_busy:
    if (NULL != descriptor) {
        *descriptor = mca_btl_smcuda_alloc(btl, endpoint, order, length, flags);
    }
    return OPAL_ERR_RESOURCE_BUSY;
}

/**
 * Initiate a send to the peer.
 *
 * @param btl (IN)      BTL module
 * @param peer (IN)     BTL peer addressing
 */
int mca_btl_smcuda_send(struct mca_btl_base_module_t *btl, struct mca_btl_base_endpoint_t *endpoint,
                        struct mca_btl_base_descriptor_t *descriptor, mca_btl_base_tag_t tag)
{
    mca_btl_smcuda_frag_t *frag = (mca_btl_smcuda_frag_t *) descriptor;
    int rc;

    if (mca_btl_smcuda_component.num_outstanding_frags * 2
        > (int) mca_btl_smcuda_component.fifo_size) {
        mca_btl_smcuda_component_progress();
    }
    /* Initiate setting up CUDA IPC support */
    if (0 == strcmp(opal_accelerator_base_selected_component.base_version.mca_component_name, "cuda") && (IPC_INIT == endpoint->ipcstate)
        && mca_btl_smcuda_component.use_cuda_ipc) {
        mca_btl_smcuda_send_cuda_ipc_request(btl, endpoint);
    }

    /* available header space */
    frag->hdr->len = frag->segment.seg_len;
    /* type of message, pt-2-pt, one-sided, etc */
    frag->hdr->tag = tag;

    MCA_BTL_SMCUDA_TOUCH_DATA_TILL_CACHELINE_BOUNDARY(frag);

    frag->endpoint = endpoint;

    /*
     * post the descriptor in the queue - post with the relative
     * address
     */
    OPAL_THREAD_ADD_FETCH32(&mca_btl_smcuda_component.num_outstanding_frags, +1);
    MCA_BTL_SMCUDA_FIFO_WRITE(endpoint, endpoint->my_smp_rank, endpoint->peer_smp_rank,
                              (void *) VIRTUAL2RELATIVE(frag->hdr), false, true, rc);
    if (OPAL_LIKELY(0 == rc)) {
        return 1; /* the data is completely gone */
    }
    frag->base.des_flags |= MCA_BTL_DES_SEND_ALWAYS_CALLBACK;
    /* not yet gone, but pending. Let the upper level knows that
     * the callback will be triggered when the data will be sent.
     */
    return 0;
}

static struct mca_btl_base_registration_handle_t *
mca_btl_smcuda_register_mem(struct mca_btl_base_module_t *btl,
                            struct mca_btl_base_endpoint_t *endpoint, void *base, size_t size,
                            uint32_t flags)
{
    mca_btl_smcuda_t *smcuda_module = (mca_btl_smcuda_t *) btl;
    mca_opal_cuda_reg_t *reg;
    int access_flags = flags & MCA_BTL_REG_FLAG_ACCESS_ANY;
    int rcache_flags = 0;

#if OPAL_CUDA_GDR_SUPPORT
    if (MCA_BTL_REG_FLAG_CUDA_GPU_MEM & flags) {
        rcache_flags |= MCA_RCACHE_FLAGS_ACCELERATOR_MEM;
    }
#endif

    smcuda_module->rcache->rcache_register(smcuda_module->rcache, base, size, rcache_flags,
                                           access_flags, (mca_rcache_base_registration_t **) &reg);
    if (OPAL_UNLIKELY(NULL == reg)) {
        return NULL;
    }

    return (mca_btl_base_registration_handle_t *) &reg->data;
}

static int mca_btl_smcuda_deregister_mem(struct mca_btl_base_module_t *btl,
                                         struct mca_btl_base_registration_handle_t *handle)
{
    mca_btl_smcuda_t *smcuda_module = (mca_btl_smcuda_t *) btl;
    mca_opal_cuda_reg_t *reg = (mca_opal_cuda_reg_t
                                             *) ((intptr_t) handle
                                                 - offsetof(mca_opal_cuda_reg_t, data));

    smcuda_module->rcache->rcache_deregister(smcuda_module->rcache, &reg->base);

    return OPAL_SUCCESS;
}

/*
 * Put remote event on stream to ensure that the the start of the
 * copy does not start until the completion of the event.
 */
static void mca_btl_smcuda_wait_stream_synchronize(mca_opal_cuda_reg_t *rget_reg)
{
#if OPAL_CUDA_SYNC_MEMOPS
    /* No need for any of this with SYNC_MEMOPS feature */
    return;
#else /* OPAL_CUDA_SYNC_MEMOPS */
    CUipcEventHandle evtHandle;
    CUevent event;
    CUresult result;

    memcpy(&evtHandle, rget_reg->data.evtHandle, sizeof(evtHandle));

    result = cuIpcOpenEventHandle(&event, evtHandle);
    if (OPAL_UNLIKELY(CUDA_SUCCESS != result)) {
        opal_output_verbose(10, mca_btl_smcuda_component.cuda_ipc_output,
                            "cuIpcOpenEventHandle failed");
    }

    /* BEGIN of Workaround - There is a bug in CUDA 4.1 RC2 and earlier
     * versions.  Need to record an event on the stream, even though
     * it is not used, to make sure we do not short circuit our way
     * out of the cuStreamWaitEvent test.
     */
    result = cuEventRecord(event, 0);
    if (OPAL_UNLIKELY(CUDA_SUCCESS != result)) {
        opal_output_verbose(10, mca_btl_smcuda_component.cuda_ipc_output,
                            "cuEventRecord failed");
    }
    /* END of Workaround */

    result = cuStreamWaitEvent(0, event, 0);
    if (OPAL_UNLIKELY(CUDA_SUCCESS != result)) {
        opal_output_verbose(10, mca_btl_smcuda_component.cuda_ipc_output,
                            "cuStreamWaitEvent failed");
    }

    /* All done with this event. */
    result = cuEventDestroy(event);
    if (OPAL_UNLIKELY(CUDA_SUCCESS != result)) {
        opal_output_verbose(10, mca_btl_smcuda_component.cuda_ipc_output,
                            "cuStreamWaitEvent failed");
    }
#endif /* OPAL_CUDA_SYNC_MEMOPS */
}

int mca_btl_smcuda_get_cuda(struct mca_btl_base_module_t *btl, struct mca_btl_base_endpoint_t *ep,
                            void *local_address, uint64_t remote_address,
                            struct mca_btl_base_registration_handle_t *local_handle,
                            struct mca_btl_base_registration_handle_t *remote_handle, size_t size,
                            int flags, int order, mca_btl_base_rdma_completion_fn_t cbfunc,
                            void *cbcontext, void *cbdata)
{
    mca_opal_cuda_reg_t rget_reg;
    mca_opal_cuda_reg_t *reg_ptr = &rget_reg;
    int rc, done;
    void *remote_memory_address;
    size_t offset;
    mca_btl_smcuda_frag_t *frag;

    /* NTH: copied from old prepare_dst function */
    MCA_BTL_SMCUDA_FRAG_ALLOC_USER(frag);
    if (OPAL_UNLIKELY(NULL == frag)) {
        return OPAL_ERR_OUT_OF_RESOURCE;
    }

    /* shove all the info needed for completion callbacks into the fragment */
    frag->segment.seg_len = size;
    frag->segment.seg_addr.pval = local_address;
    frag->base.des_segments = &frag->segment;
    frag->base.des_segment_count = 1;
    frag->base.des_flags = flags;
    frag->base.des_cbfunc = (mca_btl_base_completion_fn_t) cbfunc;
    frag->base.des_cbdata = cbdata;
    frag->base.des_context = cbcontext;
    frag->local_handle = local_handle;

    /* Set to 0 for debugging since it is a list item but I am not
     * initializing it properly and it is annoying to see all the
     * garbage in the debugger.  */

    memset(&rget_reg, 0, sizeof(rget_reg));
    memcpy(&rget_reg.data.memHandle, remote_handle->reg_data.memHandle,
           sizeof(remote_handle->reg_data.memHandle));
#    if !OPAL_CUDA_SYNC_MEMOPS
    /* Only need the remote event handle when syncing with remote events */
    memcpy(&rget_reg.data.evtHandle, remote_handle->reg_data.evtHandle,
           sizeof(remote_handle->reg_data.evtHandle));
#    endif

    /* Open the memory handle to the remote memory.  If it is cached, then
     * we just retrieve it from cache and avoid a call to open the handle.  That
     * is taken care of in the memory pool.  Note that we are searching for the
     * memory based on the base address and size of the memory handle, not the
     * remote memory which may lie somewhere in the middle. This is taken care of
     * a few lines down. Note that we hand in the peer rank just for debugging
     * support. */
    rc = ep->rcache->rcache_register(ep->rcache, remote_handle->reg_data.memh_seg_addr.pval,
                                     remote_handle->reg_data.memh_seg_len, ep->peer_smp_rank,
                                     MCA_RCACHE_ACCESS_LOCAL_WRITE,
                                     (mca_rcache_base_registration_t **) &reg_ptr);

    if (OPAL_SUCCESS != rc) {
        opal_output(0, "Failed to register remote memory, rc=%d", rc);
        return rc;
    }
    frag->registration = (mca_rcache_base_registration_t *) reg_ptr;
    frag->endpoint = ep;

    /* The registration has given us back the memory block that this
     * address lives in.  However, the base address of the block may
     * not equal the address that was used to retrieve the block.
     * Therefore, compute the offset and add it to the address of the
     * memory handle. */
    offset = (size_t)((intptr_t) remote_address - (intptr_t) reg_ptr->base.base);
    remote_memory_address = (unsigned char *) reg_ptr->base.alloc_base + offset;
    if (0 != offset) {
        opal_output(-1, "OFFSET=%d", (int) offset);
    }

    /* The remote side posted an IPC event to make sure we do not start our
     * copy until IPC event completes.  This is to ensure that the data being sent
     * is available in the sender's GPU buffer.  Therefore, do a stream synchronize
     * on the IPC event that we received.  Note that we pull it from
     * rget_reg, not reg_ptr, as we do not cache the event. */
    mca_btl_smcuda_wait_stream_synchronize(&rget_reg);

    rc = mca_btl_smcuda_memcpy(local_address, remote_memory_address, size, "mca_btl_smcuda_get",
                                (mca_btl_base_descriptor_t *) frag);
    if (OPAL_SUCCESS != rc) {
        /* Out of resources can be handled by upper layers. */
        if (OPAL_ERR_OUT_OF_RESOURCE != rc) {
            opal_output(0, "Failed to cuMemcpy GPU memory, rc=%d", rc);
        }
        return rc;
    }

    return OPAL_SUCCESS;
}

/**
 * Send a CUDA IPC request message to the peer.  This indicates that this rank
 * is interested in establishing CUDA IPC support between this rank and GPU
 * and the remote rank and GPU.  This is called when we do a send of some
 * type.
 *
 * @param btl (IN)      BTL module
 * @param peer (IN)     BTL peer addressing
 */
#    define MAXTRIES 5
static void mca_btl_smcuda_send_cuda_ipc_request(struct mca_btl_base_module_t *btl,
                                                 struct mca_btl_base_endpoint_t *endpoint)
{
    mca_btl_smcuda_frag_t *frag;
    int rc, mydevnum, res;
    ctrlhdr_t ctrlhdr;

    /* We need to grab the lock when changing the state from IPC_INIT as multiple
     * threads could be doing sends. */
    OPAL_THREAD_LOCK(&endpoint->endpoint_lock);
    if (endpoint->ipcstate != IPC_INIT) {
        OPAL_THREAD_UNLOCK(&endpoint->endpoint_lock);
        return;
    }
    endpoint->ipctries++;
    if (endpoint->ipctries > MAXTRIES) {
        endpoint->ipcstate = IPC_BAD;
        OPAL_THREAD_UNLOCK(&endpoint->endpoint_lock);
        return;
    }
    /* All is good.  Set up state and continue. */
    endpoint->ipcstate = IPC_SENT;
    OPAL_THREAD_UNLOCK(&endpoint->endpoint_lock);

    if (mca_btl_smcuda_component.num_outstanding_frags * 2
        > (int) mca_btl_smcuda_component.fifo_size) {
        mca_btl_smcuda_component_progress();
    }

    if (0 != (res = opal_accelerator.get_device(&mydevnum))) {
        opal_output(0, "Cannot determine device.  IPC cannot be set.");
        endpoint->ipcstate = IPC_BAD;
        return;
    }

    /* allocate a fragment, giving up if we can't get one */
    MCA_BTL_SMCUDA_FRAG_ALLOC_EAGER(frag);
    if (OPAL_UNLIKELY(NULL == frag)) {
        endpoint->ipcstate = IPC_BAD;
        return;
    }

    /* Fill in fragment fields. */
    frag->hdr->tag = MCA_BTL_TAG_SMCUDA;
    frag->base.des_flags = MCA_BTL_DES_FLAGS_BTL_OWNERSHIP;
    frag->endpoint = endpoint;
    ctrlhdr.ctag = IPC_REQ;
    ctrlhdr.cudev = mydevnum;
    memcpy(frag->segment.seg_addr.pval, &ctrlhdr, sizeof(struct ctrlhdr_st));

    MCA_BTL_SMCUDA_TOUCH_DATA_TILL_CACHELINE_BOUNDARY(frag);
    /* write the fragment pointer to the FIFO */
    /*
     * Note that we don't care what the FIFO-write return code is.  Even if
     * the return code indicates failure, the write has still "completed" from
     * our point of view:  it has been posted to a "pending send" queue.
     */
    OPAL_THREAD_ADD_FETCH32(&mca_btl_smcuda_component.num_outstanding_frags, +1);
    opal_output_verbose(10, mca_btl_smcuda_component.cuda_ipc_output,
                        "Sending CUDA IPC REQ (try=%d): myrank=%d, mydev=%d, peerrank=%d",
                        endpoint->ipctries, mca_btl_smcuda_component.my_smp_rank, mydevnum,
                        endpoint->peer_smp_rank);

    MCA_BTL_SMCUDA_FIFO_WRITE(endpoint, endpoint->my_smp_rank, endpoint->peer_smp_rank,
                              (void *) VIRTUAL2RELATIVE(frag->hdr), false, true, rc);
    return;
}

/**
 *
 */
void mca_btl_smcuda_dump(struct mca_btl_base_module_t *btl,
                         struct mca_btl_base_endpoint_t *endpoint, int verbose)
{
    mca_btl_smcuda_frag_t *frag;

    mca_btl_base_err("BTL SM %p endpoint %p [smp_rank %d] [peer_rank %d]\n", (void *) btl,
                     (void *) endpoint, endpoint->my_smp_rank, endpoint->peer_smp_rank);
    if (NULL != endpoint) {
        OPAL_LIST_FOREACH (frag, &endpoint->pending_sends, mca_btl_smcuda_frag_t) {
            mca_btl_base_err(" |  frag %p size %lu (hdr frag %p len %lu rank %d tag %d)\n",
                             (void *) frag, frag->size, (void *) frag->hdr->frag, frag->hdr->len,
                             frag->hdr->my_smp_rank, frag->hdr->tag);
        }
    }
}
