SPU_RUN(2)		   Linux Programmer's Manual		    SPU_RUN(2)



NAME
       spu_run - execute an SPU context

SYNOPSIS
       #include <sys/spu.h>

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

       Note: There is no glibc wrapper for this system call; see NOTES.

DESCRIPTION
       The  spu_run()  system  call is used on PowerPC machines that implement
       the Cell Broadband Engine Architecture in order to  access  Synergistic
       Processor  Units (SPUs).	 The fd argument is a file descriptor returned
       by spu_create(2) that refers to a specific SPU context.	When the  con-
       text  gets  scheduled  to  a  physical  SPU, it starts execution at the
       instruction pointer passed in npc.

       Execution of SPU code happens  synchronously,  meaning  that  spu_run()
       blocks  while  the SPU is still running.	 If there is a need to execute
       SPU code in parallel with other code on either the main	CPU  or	 other
       SPUs,  a	 new  thread  of  execution must be created first (e.g., using
       pthread_create(3)).

       When spu_run() returns, the current value of the SPU program counter is
       written	to  npc, so successive calls to spu_run() can use the same npc
       pointer.

       The event argument provides a buffer for an extended status  code.   If
       the  SPU	 context  was created with the SPU_CREATE_EVENTS_ENABLED flag,
       then this buffer is populated by	 the  Linux  kernel  before  spu_run()
       returns.

       The status code may be one (or more) of the following constants:

       SPE_EVENT_DMA_ALIGNMENT
	      A DMA alignment error occurred.

       SPE_EVENT_INVALID_DMA
	      An invalid MFC DMA command was attempted.

       SPE_EVENT_SPE_DATA_STORAGE
	      A DMA storage error occurred.

       SPE_EVENT_SPE_ERROR
	      An illegal instruction was executed.

       NULL is a valid value for the event argument.  In this case, the events
       will not be reported to the calling process.

RETURN VALUE
       On success, spu_run() returns the value of the spu_status register.  On
       error,  it  returns  -1 and sets errno to one of the error codes listed
       below.

       The spu_status register value is a bit mask of status codes and option-
       ally 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 a stop-and-signal instruction.

       0x04   SPU was stopped by a halt instruction.

       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 a
	      stop-and-signal  instruction.   These bits are valid only if the
	      0x02 bit is set.

       If spu_run() has not returned an error, one  or	more  bits  among  the
       lower eight ones are always set.

ERRORS
       EBADF  fd is not a valid file descriptor.

       EFAULT npc  is not a valid pointer, or event is non-NULL and an invalid
	      pointer.

       EINTR  A signal occurred while spu_run()	 was  in  progress;  see  sig-
	      nal(7).	The  npc  value	 has  been  updated to the new program
	      counter value if necessary.

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

       ENOMEM There was not enough memory available to	handle	a  page	 fault
	      resulting	 from  a  Memory  Flow	Controller (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.

VERSIONS
       The spu_run() system call was added to Linux in kernel 2.6.16.

CONFORMING TO
       This call is Linux-specific and implemented only by the PowerPC	archi-
       tecture.	 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_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 recommended libraries.

EXAMPLE
       The  following  is  an example of running a simple, one-instruction SPU
       program with the spu_run() system call.

       #include <stdlib.h>
       #include <stdint.h>
       #include <unistd.h>
       #include <stdio.h>
       #include <sys/types.h>
       #include <fcntl.h>

       #define handle_error(msg) \
	   do { perror(msg); exit(EXIT_FAILURE); } while (0)

       int main(void)
       {
	   int context, fd, spu_status;
	   uint32_t instruction, npc;

	   context = spu_create("/spu/example-context", 0, 0755);
	   if (context == -1)
	       handle_error("spu_create");

	   /* write a 'stop 0x1234' instruction to the SPU's
	    * local store memory
	    */
	   instruction = 0x00001234;

	   fd = open("/spu/example-context/mem", O_RDWR);
	   if (fd == -1)
	       handle_error("open");
	   write(fd, &instruction, sizeof(instruction));

	   /* set npc to the starting instruction address of the
	    * SPU program. Since we wrote the instruction at the
	    * start of the mem file, the entry point will be 0x0
	    */
	   npc = 0;

	   spu_status = spu_run(context, &npc, NULL);
	   if (spu_status == -1)
	       handle_error("open");

	   /* we should see a status code of 0x1234002:
	    *	0x00000002 (spu was stopped due to stop-and-signal)
	    * | 0x12340000 (the stop-and-signal code)
	    */
	   printf("SPU Status: 0x%08x\n", spu_status);

	   exit(EXIT_SUCCESS);
       }

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

COLOPHON
       This page is part of release 4.10 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/.



Linux				  2012-08-05			    SPU_RUN(2)