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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);

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_cre-
       ate() 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_CRE-
              ATE_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 Ele-
              ment) 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 con-
              text 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_cre-
       ate()  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 3.22 of the Linux man-pages project.  A description of the project, and informa-
       tion about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



Linux                             2007-12-20                     SPU_CREATE(2)