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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 filesys-
       tem  (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 con-
       text 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 con-
       stants:

       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  parame-
	      ters--priority and policy.  In the future, gang scheduling may be implemented caus-
	      ing 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  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)) 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 hard-
	      ware 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  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 3.55 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/.

Linux					    2012-08-05				    SPU_CREATE(2)
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