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
       context 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 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 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 signal(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 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_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
", spu_status);

	   exit(EXIT_SUCCESS);
       }

SEE ALSO

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

COLOPHON

       This page is part of release 4.15 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								    2017-09-15								SPU_RUN(2)