SPU_CREATE(2)             (2020-12-21)              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 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 cre-
          ates 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 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 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.

          The neighbor_fd is used only when the
          SPU_CREATE_AFFINITY_SPU flag is specified; see below.

          The flags argument can be zero or any bitwise OR-ed combina-
          tion 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

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               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 speci-
               fied 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 sched-
               uler.  Once the context is run, it will not be sched-
               uled 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 (since Linux 2.6.23)
               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 (since Linux 2.6.23)
               Create a context with affinity to system memory.  This
               affinity information is used within the SPU scheduling
               algorithm.

     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.

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     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 contexts has been reached.

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

          ENOTDIR

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               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 Pow-
          erPC 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 for the recommended libraries.

          Prior to the addition of the SPU_CREATE_AFFINITY_SPU flag in
          Linux 2.6.23, the spu_create() system call took only three
          arguments (i.e., there was no neighbor_fd argument).

     EXAMPLES
          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 5.10 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/.

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