SPU_CREATE(2)		   Linux Programmer's Manual		 SPU_CREATE(2)



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);

       Note: There is no glibc wrapper for this system call; see NOTES.

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  nonexistent directory in the mount point of the SPU
       filesystem (spufs).  If spu_create() is successful, a directory is cre-
       ated  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 cre-
       ated 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 con-
	      texts, 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 func-
	      tionality 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_CRE-
	      ATE_NOSCHED flag.

       SPU_CREATE_AFFINITY_SPU
	      Create  a	 context  with	affinity to another SPU context.  This
	      affinity information is used within  the	SPU  scheduling	 algo-
	      rithm.   Using  this flag requires that a file descriptor refer-
	      ring to the other SPU context be passed in the neighbor_fd argu-
	      ment.

       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)) speci-
       fies 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 pathname.

       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 per-process limit on the number of open file descriptors has
	      been reached.

       ENAMETOOLONG
	      pathname is too long.

       ENFILE The system-wide limit on the total number of open files has been
	      reached.

       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  con-
	      texts 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 implemented only on the PowerPC archi-
       tecture.	 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 4.10 of the Linux  man-pages  project.   A
       description  of	the project, information about reporting bugs, and the
       latest	 version    of	  this	  page,	   can	   be	  found	    at
       https://www.kernel.org/doc/man-pages/.



Linux				  2015-12-28			 SPU_CREATE(2)