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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/spu.h>          /* Definition of SPU_* constants */
       #include <sys/syscall.h>      /* Definition of SYS_* constants */
       #include <unistd.h>

       int syscall(SYS_spu_create, const char *pathname, unsigned int flags,
                   mode_t mode, int neighbor_fd);

       Note: glibc provides no wrapper for spu_create(), necessitating the use of syscall(2).

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  direc‐
       tory  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 de‐
       scribed 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 direc‐
       tory) 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 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 (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 failure, -1 is returned, and errno is set to indicate the error.

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 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 architecture.  Programs using this system call are not portable.

NOTES
       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.

       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)

Linux                                                                          2021-03-22                                                                  SPU_CREATE(2)