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NAME

       spu_create - create a new spu context

SYNOPSIS

       #include <sys/types.h>
       #include <sys/spu.h>

       int spu_create(const char *pathname, int flags, mode_t mode);
       int spu_create(const char *pathname, int flags, mode_t mode,
                      int neighbor_fd);

DESCRIPTION

       The spu_create() system call is used on PowerPC machines that implement
       the Cell Broadband Engine Architecture in order to  access  Synergistic
       Processor Units (SPUs).  It creates a new logical context for an SPU in
       pathname and returns a file descriptor associated  with  it.   pathname
       must  refer  to  a non-existing directory in the mount point of the SPU
       file system (spufs).  If spu_create() is  successful,  a  directory  is
       created  at  pathname  and  it is populated with the files described in
       spufs(7).

       When a context is created, the returned file  descriptor  can  only  be
       passed  to  spu_run(2), used as the dirfd argument to the *at family of
       system calls (e.g., openat(2)), or closed;  other  operations  are  not
       defined.   A  logical  SPU  context  is destroyed (along with all files
       created  within  the  context’s  pathname  directory)  once  the   last
       reference  to  the  context has gone; this usually occurs when the file
       descriptor returned by spu_create() is closed.

       The flags argument can be zero or any bitwise OR-ed combination of  the
       following constants:

       SPU_CREATE_EVENTS_ENABLED
              Rather  than  using  signals  for  reporting DMA errors, use the
              event argument to spu_run(2).

       SPU_CREATE_GANG
              Create an SPU gang instead of a context.  (A gang is a group  of
              SPU  contexts  that  are  functionally related to each other and
              which share common scheduling parameters — priority and  policy.
              In  the  future,  gang scheduling may be implemented causing the
              group to be switched in and out as a single unit.)

              A new directory will be created at the location specified by the
              pathname  argument.   This  gang  may  be used to hold other SPU
              contexts, by providing  a  pathname  that  is  within  the  gang
              directory to further calls to spu_create().

       SPU_CREATE_NOSCHED
              Create  a  context  that  is  not affected by the SPU scheduler.
              Once the context is run, it will not be scheduled out  until  it
              is destroyed by the creating process.

              Because  the  context  cannot  be  removed  from  the  SPU, some
              functionality is disabled for SPU_CREATE_NOSCHED contexts.  Only
              a  subset  of  the  files  will  be  available  in  this context
              directory in spufs.  Additionally,  SPU_CREATE_NOSCHED  contexts
              cannot dump a core file when crashing.

              Creating  SPU_CREATE_NOSCHED  contexts requires the CAP_SYS_NICE
              capability.

       SPU_CREATE_ISOLATE
              Create an isolated SPU context.  Isolated contexts are protected
              from  some  PPE (PowerPC Processing Element) operations, such as
              access to the SPU local store and the NPC register.

              Creating   SPU_CREATE_ISOLATE   contexts   also   requires   the
              SPU_CREATE_NOSCHED flag.

       SPU_CREATE_AFFINITY_SPU
              Create  a  context  with  affinity to another SPU context.  This
              affinity  information  is  used  within   the   SPU   scheduling
              algorithm.   Using  this  flag  requires  that a file descriptor
              referring to the other SPU context be passed in the  neighbor_fd
              argument.

       SPU_CREATE_AFFINITY_MEM
              Create  a context with affinity to system memory.  This affinity
              information is used within the SPU scheduling algorithm.

       The mode argument (minus  any  bits  set  in  the  process’s  umask(2))
       specifies the permissions used for creating the new directory in spufs.
       See stat(2) for a full list of the possible mode values.

RETURN VALUE

       On success, spu_create() returns a new file descriptor.  On  error,  -1
       is returned, and errno is set to one of the error codes listed below.

ERRORS

       EACCES The  current  user  does  not  have write access to the spufs(7)
              mount point.

       EEXIST An SPU context already exists at the given path name.

       EFAULT pathname is not a valid string pointer in the calling  process’s
              address space.

       EINVAL pathname  is  not  a  directory  in the spufs(7) mount point, or
              invalid flags have been provided.

       ELOOP  Too many symbolic links were found while resolving pathname.

       EMFILE The process has reached its maximum open files limit.

       ENAMETOOLONG
              pathname is too long.

       ENFILE The system has reached the global open files limit.

       ENODEV An isolated context was requested, but  the  hardware  does  not
              support SPU isolation.

       ENOENT Part of pathname could not be resolved.

       ENOMEM The kernel could not allocate all resources required.

       ENOSPC There  are  not  enough  SPU resources available to create a new
              context or  the  user-specific  limit  for  the  number  of  SPU
              contexts has been reached.

       ENOSYS The functionality is not provided by the current system, because
              either the hardware does not provide SPUs or the spufs module is
              not loaded.

       ENOTDIR
              A part of pathname is not a directory.

       EPERM  The  SPU_CREATE_NOSCHED  flag  has been given, but the user does
              not have the CAP_SYS_NICE capability.

FILES

       pathname must point to a location beneath the mount point of spufs.  By
       convention, it gets mounted in /spu.

VERSIONS

       The spu_create() system call was added to Linux in kernel 2.6.16.

CONFORMING TO

       This  call  is  Linux-specific  and  only  implemented  on  the PowerPC
       architecture.  Programs using this system call are not portable.

NOTES

       Glibc does not provide a wrapper for this system call;  call  it  using
       syscall(2).   Note  however, that spu_create() is meant to be used from
       libraries that implement a more abstract interface to SPUs, not  to  be
       used          from          regular          applications.          See
       http://www.bsc.es/projects/deepcomputing/linuxoncell/      for      the
       recommended libraries.

EXAMPLE

       See spu_run(2) for an example of the use of spu_create()

SEE ALSO

       close(2), spu_run(2), capabilities(7), spufs(7)

COLOPHON

       This  page  is  part of release 3.01 of the Linux man-pages project.  A
       description of the project, and information about reporting  bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.