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man:spu_run

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 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 4.16 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)

/data/webs/external/dokuwiki/data/pages/man/spu_run.txt · Last modified: 2019/05/17 09:47 by 127.0.0.1

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