spu_run - execute an spu context

   ::

    #include <sys/spu.h>

    int spu_run(int fd, unsigned int *npc, unsigned int *event);

   The  spu_run system call is used on PowerPC machines that implement the
   Cell Broadband Engine Architecture in order to access Synergistic  Pro-
   cessor  Units  (SPUs).  It  uses the fd that was returned from spu_cre-
   ate(2) to address a specific SPU context. When the context gets  sched-
   uled  to a physical SPU, it starts execution at the instruction pointer
   passed in npc.

   Execution of SPU code happens synchronously, meaning that spu_run  does
   not  return  while the SPU is still running. If there is a need to exe-
   cute SPU code in parallel with other code on either  the  main  CPU  or
   other  SPUs,  you  need to create a new thread of execution first, e.g.
   using the pthread_create(3) call.

   When spu_run returns, the current value of the SPU instruction  pointer
   is  written back to npc, so you can call spu_run again without updating
   the pointers.

   event can be a NULL pointer or point to an extended  status  code  that
   gets  filled  when spu_run returns. It can be one of the following con-
   stants:

   SPE_EVENT_DMA_ALIGNMENT
          A DMA alignment error

   SPE_EVENT_SPE_DATA_SEGMENT
          A DMA segmentation error

   SPE_EVENT_SPE_DATA_STORAGE
          A DMA storage error

   If NULL is passed as the event argument, these errors will result in  a
   signal delivered to the calling process.

   spu_run  returns the value of the spu_status register or -1 to indicate
   an error and set errno to one of the error  codes  listed  below.   The
   spu_status  register  value  contains  a  bit  mask of status codes and
   optionally a 14 bit code returned from the stop-and-signal  instruction
   on the SPU. The bit masks for the status codes are:

   0x02
      SPU was stopped by stop-and-signal.

   0x04
      SPU was stopped by halt.

   0x08
      SPU is waiting for a channel.

   0x10
      SPU is in single-step mode.

   0x20
      SPU has tried to execute an invalid instruction.

   0x40
      SPU has tried to access an invalid channel.

   0x3fff0000
          The  bits  masked with this value contain the code returned from
          stop-and-signal.

   There are always one or more of the lower eight bits set  or  an  error
   code is returned from spu_run.

   EAGAIN or EWOULDBLOCK
          fd is in non-blocking mode and spu_run would block.

   EBADF  fd is not a valid file descriptor.

   EFAULT npc is not a valid pointer or status is neither NULL nor a valid
          pointer.

   EINTR  A signal occurred while spu_run was in progress.  The npc  value
          has  been updated to the new program counter value if necessary.

   EINVAL fd is not a file descriptor returned from spu_create(2).

   ENOMEM Insufficient memory was available to handle a page fault result-
          ing from an MFC direct memory access.

   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.

   spu_run  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 rec-
   ommended libraries.

   This call is Linux specific and only implemented by the ppc64 architec-
   ture. Programs using this system call are not portable.

   The code does not yet fully implement all features lined out here.

   Arnd Bergmann <[email protected]>

   capabilities(7), close(2), spu_create(2), spufs(7)