Provided by: libfabric-dev_1.6.2-3_amd64 bug

NAME

       fi_mr - Memory region operations

       fi_mr_reg  /  fi_mr_regv / fi_mr_regattr : Register local memory buffers for direct fabric
       access

       fi_close : Deregister registered memory buffers.

       fi_mr_desc : Return a local descriptor associated with a registered memory region

       fi_mr_key : Return the remote key needed to access a registered memory region

       fi_mr_raw_attr : Return raw memory region attributes.

       fi_mr_map_raw : Converts a raw memory region key into  a  key  that  is  usable  for  data
       transfer operations.

       fi_mr_unmap_key : Releases a previously mapped raw memory region key.

       fi_mr_bind : Associate a registered memory region with a completion counter.

       fi_mr_refresh : Updates the memory pages associated with a memory region.

       fi_mr_enable : Enables a memory region for use.

SYNOPSIS

              #include <rdma/fi_domain.h>

              int fi_mr_reg(struct fid_domain *domain, const void *buf, size_t len,
                  uint64_t access, uint64_t offset, uint64_t requested_key,
                  uint64_t flags, struct fid_mr **mr, void *context);

              int fi_mr_regv(struct fid_domain *domain, const struct iovec * iov,
                  size_t count, uint64_t access, uint64_t offset, uint64_t requested_key,
                  uint64_t flags, struct fid_mr **mr, void *context);

              int fi_mr_regattr(struct fid_domain *domain, const struct fi_mr_attr *attr,
                  uint64_t flags, struct fid_mr **mr);

              int fi_close(struct fid *mr);

              void * fi_mr_desc(struct fid_mr *mr);

              uint64_t fi_mr_key(struct fid_mr *mr);

              int fi_mr_raw_attr(struct fid_mr *mr, uint64_t *base_addr,
                  uint8_t *raw_key, size_t *key_size, uint64_t flags);

              int fi_mr_map_raw(struct fid_domain *domain, uint64_t base_addr,
                  uint8_t *raw_key, size_t key_size, uint64_t *key, uint64_t flags);

              int fi_mr_unmap_key(struct fid_domain *domain, uint64_t key);

              int fi_mr_bind(struct fid_mr *mr, struct fid *bfid, uint64_t flags);

              int fi_mr_refresh(struct fid_mr *mr, const struct iovec *iov, size, count,
                  uint64_t flags)

              int fi_mr_enable(struct fid_mr *mr);

ARGUMENTS

       domain : Resource domain

       mr : Memory region

       bfid : Fabric identifier of an associated resource.

       context : User specified context associated with the memory region.

       buf : Memory buffer to register with the fabric hardware

       len : Length of memory buffer to register

       iov : Vectored memory buffer.

       count : Count of vectored buffer entries.

       access : Memory access permissions associated with registration

       offset  :  Optional  specified  offset  for  accessing specified registered buffers.  This
       parameter is reserved for future use and must be 0.

       requested_key : Optional requested remote key associated with registered buffers.

       attr : Memory region attributes

       flags : Additional flags to apply to the operation.

DESCRIPTION

       Registered memory regions associate memory buffers with permissions granted for access  by
       fabric resources.  A memory buffer must be registered with a resource domain before it can
       be used as the target of a remote RMA or atomic data  transfer.   Additionally,  a  fabric
       provider may require that data buffers be registered before being used in local transfers.
       Memory registration restrictions are  controlled  using  a  separate  set  of  mode  bits,
       specified through the domain attributes (mr_mode field).

       The following apply to memory registration.

       Scalable  Memory  Registration  :  By default, memory registration is considered scalable.
       (For  library  versions  1.4  and  earlier,  this  is  indicated  by  setting  mr_mode  to
       FI_MR_SCALABLE,  with  the  fi_info  mode bit FI_LOCAL_MR set to 0).  For versions 1.5 and
       later, scalable is implied by the lack of any mr_mode bits  being  set.   The  setting  of
       mr_mode bits therefore adjusts application behavior as described below.  Default, scalable
       registration has several properties.

       In scalable mode, registration occurs on  memory  address  ranges.   Because  registration
       refers to memory regions, versus data buffers, the address ranges given for a registration
       request do not need to map to data buffers allocated by the application at  the  time  the
       registration call is made.  That is, an application can register any range of addresses in
       their virtual address space, whether or not those addresses are backed by  physical  pages
       or have been allocated.

       The  resulting  memory  regions  are  accessible by peers starting at a base address of 0.
       That is, the target address that is specified is a byte offset into the registered region.

       The application also selects the access key associated with  the  MR.   The  key  size  is
       restricted to a maximum of 8 bytes.

       With  scalable  registration,  locally  accessed  data  buffers  are not registered.  This
       includes source buffers for all transmit operations  --  sends,  tagged  sends,  RMA,  and
       atomics -- as well as buffers posted for receive and tagged receive operations.

       FI_MR_LOCAL  :  When  the FI_MR_LOCAL mode bit is set, applications must register all data
       buffers that will be accessed by the local hardware and provide a valid mem_desc parameter
       into  applicable data transfer operations.  When FI_MR_LOCAL is zero, applications are not
       required to register data buffers before using them for local operations (e.g.   send  and
       receive  data  buffers),  and  the  mem_desc  parameter  into  data transfer operations is
       ignored.

       A provider may hide local registration requirements from applications by making use of  an
       internal  registration  cache  or  similar  mechanisms.   Such  mechanisms,  however,  may
       negatively impact performance for some applications, notably those which manage their  own
       network  buffers.  In order to support as broad range of applications as possible, without
       unduly affecting their performance, applications that  wish  to  manage  their  own  local
       memory registrations may do so by using the memory registration calls.

       Note:  the  FI_MR_LOCAL  mr_mode  bit  replaces  the  FI_LOCAL_MR  fi_info mode bit.  When
       FI_MR_LOCAL is set, FI_LOCAL_MR is ignored.

       FI_MR_RAW : Raw memory regions are used to support providers with keys larger than 64-bits
       or  require  setup  at  the  peer.   When  the FI_MR_RAW bit is set, applications must use
       fi_mr_raw_attr() locally and fi_mr_map_raw() at the peer before targeting a memory  region
       as part of any data transfer request.

       FI_MR_VIRT_ADDR  :  The  FI_MR_VIRT_ADDR bit indicates that the provider references memory
       regions by virtual address, rather than  a  0-based  offset.   Peers  that  target  memory
       regions  registered  with  FI_MR_VIRT_ADDR specify the destination memory buffer using the
       target's virtual address, with any offset into the region specified as virtual  address  +
       offset.   Support  of  this bit typically implies that peers must exchange addressing data
       prior to initiating any RMA or atomic operation.

       FI_MR_ALLOCATED : When set, all registered memory  regions  must  be  backed  by  physical
       memory pages at the time the registration call is made.

       FI_MR_PROV_KEY  :  This  memory  region  mode indicates that the provider does not support
       application requested MR keys.  MR keys are returned by the provider.   Applications  that
       support  FI_MR_PROV_KEY can obtain the provider key using fi_mr_key(), unless FI_MR_RAW is
       also set.  The returned key should then be exchanged with peers prior to initiating an RMA
       or atomic operation.

       FI_MR_MMU_NOTIFY  :  FI_MR_MMU_NOTIFY  is  typically  set by providers that support memory
       registration against memory regions that are not necessarily backed by allocated  physical
       pages  at the time the memory registration occurs.  (That is, FI_MR_ALLOCATED is typically
       0).  However, such providers require that applications notify the provider prior to the MR
       being  accessed  as  part  of  a  data  transfer operation.  This notification informs the
       provider that all necessary physical pages now  back  the  region.   The  notification  is
       necessary for providers that cannot hook directly into the operating system page tables or
       memory management unit.  See fi_mr_refresh() for notification details.

       FI_MR_RMA_EVENT : This mode bit indicates that the provider must configure memory  regions
       that  are associated with RMA events prior to their use.  This includes all memory regions
       that are associated with completion counters.  When set, applications must indicate  if  a
       memory  region  will  be  associated  with  a  completion  counter as part of the region's
       creation.  This is done by passing in the FI_RMA_EVENT flag  to  the  memory  registration
       call.

       Such  memory  regions  will be created in a disabled state and must be associated with all
       completion counters prior to being enabled.  To enable a memory  region,  the  application
       must  call fi_mr_enable().  After calling fi_mr_enable(), no further resource bindings may
       be made to the memory region.

       FI_MR_ENDPOINT : This mode bit indicates that the provider associates memory regions  with
       endpoints  rather  than domains.  Memory regions that are registered with the provider are
       created in a disabled state and must be bound to an endpoint prior to being  enabled.   To
       bind the MR with an endpoint, the application must use fi_mr_bind().  To enable the memory
       region, the application must call fi_mr_enable().

       Basic Memory Registration : Basic memory registration  is  indicated  by  the  FI_MR_BASIC
       mr_mode bit.  FI_MR_BASIC is maintained for backwards compatibility (libfabric version 1.4
       or earlier).  The behavior of basic registration is equivalent to  setting  the  following
       mr_mode  bits to one: FI_MR_VIRT_ADDR, FI_MR_ALLOCATED, and FI_MR_PROV_KEY.  Additionally,
       providers that support basic registration usually required FI_MR_LOCAL.  FI_MR_BASIC  must
       either  be  set alone, or in conjunction with FI_MR_LOCAL.  Other mr_mode bit pairings are
       invalid.  Unlike other mr_mode bits, if FI_MR_BASIC is set on input  to  fi_getinfo(),  it
       will  not  be cleared by the provider.  That is, setting FI_MR_BASIC to one requests basic
       registration.

       The registrations functions -- fi_mr_reg, fi_mr_regv, and fi_mr_regattr  --  are  used  to
       register  one  or  more memory regions with fabric resources.  The main difference between
       registration functions are the number and type of parameters that they  accept  as  input.
       Otherwise, they perform the same general function.

       By default, memory registration completes synchronously.  I.e.  the registration call will
       not return until  the  registration  has  completed.   Memory  registration  can  complete
       asynchronous  by  binding  the resource domain to an event queue using the FI_REG_MR flag.
       See fi_domain_bind.  When memory registration is asynchronous, in order to  avoid  a  race
       condition  between  the  registration  call returning and the corresponding reading of the
       event from the EQ, the mr output parameter will be written  before  any  event  associated
       with  the  operation  may  be  read by the application.  An asynchronous event will not be
       generated unless the registration call returns success (0).

   fi_mr_reg
       The fi_mr_reg call registers the user-specified memory buffer with  the  resource  domain.
       The  buffer  is  enabled  for  access  by the fabric hardware based on the provided access
       permissions.  See the access field description for memory region attributes below.

       Registered memory is associated with a local memory descriptor and, optionally,  a  remote
       memory  key.   A  memory  descriptor  is  a  provider  specific identifier associated with
       registered memory.  Memory descriptors often map to  hardware  specific  indices  or  keys
       associated  with the memory region.  Remote memory keys provide limited protection against
       unwanted access by a remote node.  Remote accesses to a memory region must provide the key
       associated with the registration.

       Because  MR  keys  must  be  provided  by  a  remote  process,  an application can use the
       requested_key parameter to indicate that a specific key value be  returned.   Support  for
       user  requested  keys  is  provider  specific  and  is  determined  by  the mr_mode domain
       attribute.

       Remote RMA and atomic operations indicate the location within a registered  memory  region
       by  specifying  an address.  The location is referenced by adding the offset to either the
       base virtual address of the buffer or to 0, depending on the mr_mode.

       The offset parameter is reserved for future use and must be 0.

       For asynchronous memory registration requests, the result will be  reported  to  the  user
       through  an event queue associated with the resource domain.  If successful, the allocated
       memory region structure will be returned to the user through the  mr  parameter.   The  mr
       address  must  remain  valid  until  the  registration  operation  completes.  The context
       specified with the registration request is returned with the completion event.

   fi_mr_regv
       The fi_mr_regv call adds support for a scatter-gather list to fi_mr_reg.  Multiple  memory
       buffers are registered as a single memory region.  Otherwise, the operation is the same.

   fi_mr_regattr
       The  fi_mr_regattr  call  is  a more generic, extensible registration call that allows the
       user to specify the registration request using a struct fi_mr_attr (defined below).

   fi_close
       Fi_close is used to release all resources associated with a registering a  memory  region.
       Once  unregistered,  further access to the registered memory is not guaranteed.  Active or
       queued operations that reference a memory region  being  closed  may  fail  or  result  in
       accesses  to  invalid  memory.   Applications are responsible for ensuring that a MR is no
       longer needed prior to closing it.  Note that accesses to a closed MR from a  remote  peer
       will result in an error at the peer.  The state of the local endpoint will be unaffected.

       When closing the MR, there must be no opened endpoints or counters associated with the MR.
       If resources are still associated with the MR when attempting  to  close,  the  call  will
       return -FI_EBUSY.

   fi_mr_desc
       Obtains  the  local  memory descriptor associated with a MR.  The memory registration must
       have completed successfully before invoking this call.

   fi_mr_key
       Returns the remote protection key associated with a MR.  The memory registration must have
       completed  successfully  before  invoking  this.   The  returned  key  may be used in data
       transfer operations at a peer.  If the FI_RAW_MR mode bit has been  set  for  the  domain,
       then  the  memory key must be obtained using the fi_mr_raw_key function instead.  A return
       value of FI_KEY_NOTAVAIL will be returned if the registration has not completed or  a  raw
       memory key is required.

   fi_mr_raw_attr
       Returns  the raw, remote protection key and base address associated with a MR.  The memory
       registration must have completed successfully before invoking this routine.  Use  of  this
       call  is  required  if the FI_RAW_MR mode bit has been set by the provider; however, it is
       safe to use this call with any memory region.

       A raw key must be mapped by a peer before it can be used in data transfer operations.  See
       fi_mr_map_raw below.

   fi_mr_map_raw
       Raw  protection keys must be mapped to a usable key value before they can be used for data
       transfer operations.  The mapping is done by the peer that initiates  the  RMA  or  atomic
       operation.   The mapping function takes as input the raw key and its size, and returns the
       mapped key.  Use of the fi_mr_map_raw function is required if the peer has  the  FI_RAW_MR
       mode  bit  set,  but this routine may be called on any valid key.  All mapped keys must be
       freed by calling fi_mr_unmap_key when access to  the  peer  memory  region  is  no  longer
       necessary.

   fi_mr_unmap_key
       This  call  releases  any  resources that may have been allocated as part of mapping a raw
       memory key.  All mapped keys must be freed before the corresponding domain is closed.

   fi_mr_bind
       The fi_mr_bind function associates a memory region with a counter  or  endpoint.   Counter
       bindings  are  needed  by  providers  that  support the generation of completions based on
       fabric operations.  Endpoint bindings are needed if the provider associates memory regions
       with endpoints (see FI_MR_ENDPOINT).

       When binding with a counter, the type of events tracked against the memory region is based
       on the bitwise OR of the following flags.

       FI_REMOTE_WRITE : Generates an event whenever a  remote  RMA  write  or  atomic  operation
       modifies the memory region.  Use of this flag requires that the endpoint through which the
       MR is accessed be created with the FI_RMA_EVENT capability.

       When binding the memory region to an endpoint, flags should be 0.

   fi_mr_refresh
       The use of this call is required to notify the provider of  any  change  to  the  physical
       pages  backing  a  registered memory region if the FI_MR_MMU_NOTIFY mode bit has been set.
       This call informs the provider that the page table entries associated with the region  may
       have  been  modified,  and  the  provider  should  verify and update the registered region
       accordingly.  The iov parameter is optional and may be used to specify which  portions  of
       the  registered  region  requires  updating.   Providers are only guaranteed to update the
       specified address ranges.

       The refresh operation has the effect of disabling and re-enabling access to the registered
       region.   Any  operations from peers that attempt to access the region will fail while the
       refresh is occurring.  Additionally, attempts to access the region by  the  local  process
       through libfabric APIs may result in a page fault or other fatal operation.

       The  fi_mr_refresh call is only needed if the physical pages might have been updated after
       the memory region was created.

   fi_mr_enable
       The enable call is used with memory registration associated with the FI_MR_RMA_EVENT  mode
       bit.   Memory regions created in the disabled state must be explicitly enabled after being
       fully configured by the application.  Any resource bindings to the MR must be  done  prior
       to enabling the MR.

MEMORY REGION ATTRIBUTES

       Memory  regions  are  created  using  the  following attributes.  The struct fi_mr_attr is
       passed into fi_mr_regattr, but individual fields also apply to other  memory  registration
       calls, with the fields passed directly into calls as function parameters.

              struct fi_mr_attr {
                  const struct iovec *mr_iov;
                  size_t             iov_count;
                  uint64_t           access;
                  uint64_t           requested_key;
                  void               *context;
                  size_t             auth_key_size;
                  uint8_t            *auth_key;
              };

   mr_iov
       This  is an IO vector of addresses that will represent a single memory region.  The number
       of entries in the iovec is specified by iov_count.

   iov_count
       The number of entries in the mr_iov array.  The maximum number of memory buffers that  may
       be  associated  with  a  single  memory  region  is  specified  as the mr_iov_limit domain
       attribute.  See fi_domain(3).

   access
       Indicates the type of access that the local or a  peer  endpoint  has  to  the  registered
       memory region.  Supported access permissions are the bitwise OR of the following flags:

       FI_SEND : The memory buffer may be used in outgoing message data transfers.  This includes
       fi_msg and fi_tagged operations.

       FI_RECV : The memory buffer may be  used  to  receive  inbound  message  transfers.   This
       includes fi_msg and fi_tagged operations.

       FI_READ  :  The  memory  buffer  may  be used as the result buffer for RMA read and atomic
       operations on the initiator side.

       FI_WRITE : The memory buffer may be used as the source buffer for  RMA  write  and  atomic
       operations on the initiator side.

       FI_REMOTE_READ  :  The  memory  buffer  may  be  used  as the source buffer of an RMA read
       operation on the target side.

       FI_REMOTE_WRITE : The memory buffer may be used as the target buffer of an  RMA  write  or
       atomic operation.

   requested_key
       An application specified access key associated with the memory region.  The MR key must be
       provided by a remote process when performing RMA or atomic operations to a memory  region.
       Applications  can  use  the requested_key field to indicate that a specific key be used by
       the provider.  This allows applications to use well known  key  values,  which  can  avoid
       applications  needing  to  exchange  and  store  keys.  Support for user requested keys is
       provider specific and is determined by the mr_mode domain attribute.

   context
       Application context associated with asynchronous  memory  registration  operations.   This
       value  is  returned  as  part  of any asynchronous event associated with the registration.
       This field is ignored for synchronous registration calls.

   auth_key_size
       The size of key referenced by the auth_key field in bytes, or 0 if no authorization key is
       given.  This field is ignored unless the fabric is opened with API version 1.5 or greater.

   auth_key
       Indicates the key to associate with this memory registration.  Authorization keys are used
       to limit communication between endpoints.  Only peer endpoints that are programmed to  use
       the  same  authorization  key  may access the memory region.  The domain authorization key
       will be used if the auth_key_size provided is 0.  This field is ignored unless the  fabric
       is opened with API version 1.5 or greater.

NOTES

       Direct  access  to  an application's memory by a remote peer requires that the application
       register the targeted memory buffer(s).  This is typically done  by  calling  one  of  the
       fi_mr_reg* routines.  For FI_MR_PROV_KEY, the provider will return a key that must be used
       by the peer when  accessing  the  memory  region.   The  application  is  responsible  for
       transferring  this  key  to  the  peer.   If  FI_MR_RAW mode has been set, the key must be
       retrieved using the fi_mr_raw_attr function.

       FI_RAW_MR allows support for providers that require more than 8-bytes for their protection
       keys or need additional setup before a key can be used for transfers.  After a raw key has
       been  retrieved,  it  must  be  exchanged  with  the  remote  peer.   The  peer  must  use
       fi_mr_map_raw  to  convert the raw key into a usable 64-bit key.  The mapping must be done
       even if the raw key is 64-bits or smaller.

       The raw key support functions are usable with  all  registered  memory  regions,  even  if
       FI_MR_RAW  has  not  been  set.  It is recommended that portable applications target using
       those interfaces; however, their  use  does  carry  extra  message  and  memory  footprint
       overhead, making it less desirable for highly scalable apps.

FLAGS

       The follow flag may be specified to any memory registration call.

       FI_RMA_EVENT  :  This  flag  indicates that the specified memory region will be associated
       with a completion counter used to count RMA operations that access the MR.

       FI_RMA_PMEM : This  flag  indicates  that  the  underlying  memory  region  is  backed  by
       persistent  memory and will be used in RMA operations.  It must be specified if persistent
       completion semantics  or  persistent  data  transfers  are  required  when  accessing  the
       registered region.

RETURN VALUES

       Returns  0  on  success.   On  error,  a  negative  value corresponding to fabric errno is
       returned.

       Fabric errno values are defined in rdma/fi_errno.h.

ERRORS

       -FI_ENOKEY : The requested_key is already in use.

       -FI_EKEYREJECTED : The requested_key is not available.  They key may be out of  the  range
       supported  by  the  provider,  or  the  provider  may  not  support  user-requested memory
       registration keys.

       -FI_ENOSYS : Returned by fi_mr_bind if the provider  does  not  support  reporting  events
       based on access to registered memory regions.

       -FI_EBADFLAGS : Returned if the specified flags are not supported by the provider.

SEE ALSO

       fi_getinfo(3), fi_endpoint(3), fi_domain(3), fi_rma(3), fi_msg(3), fi_atomic(3)

AUTHORS

       OpenFabrics.