spu_run(2) | System Calls Manual | spu_run(2) |
spu_run - execute an SPU context
Standard C library (libc, -lc)
#include <sys/spu.h> /* Definition of SPU_* constants */ #include <sys/syscall.h> /* Definition of SYS_* constants */ #include <unistd.h>
int syscall(SYS_spu_run, int fd, uint32_t *npc, uint32_t *event);
Note: glibc provides no wrapper for spu_run(), necessitating the use of syscall(2).
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:
NULL is a valid value for the event argument. In this case, the events will not be reported to the calling process.
On success, spu_run() returns the value of the spu_status register. On failure, it returns -1 and sets errno is set to indicate the error.
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:
If spu_run() has not returned an error, one or more bits among the lower eight ones are always set.
The spu_run() system call was added in Linux 2.6.16.
This call is Linux-specific and implemented only by the PowerPC architecture. Programs using this system call are not portable.
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.
The following is an example of running a simple, one-instruction SPU program with the spu_run() system call.
#include <err.h> #include <fcntl.h> #include <stdint.h> #include <stdio.h> #include <stdlib.h> #include <sys/types.h> #include <unistd.h> int main(void) {
int context, fd, spu_status;
uint32_t instruction, npc;
context = syscall(SYS_spu_create, "/spu/example-context", 0, 0755);
if (context == -1)
err(EXIT_FAILURE, "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)
err(EXIT_FAILURE, "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 = syscall(SYS_spu_run, context, &npc, NULL);
if (spu_status == -1)
err(EXIT_FAILURE, "open");
/*
* We should see a status code of 0x12340002:
* 0x00000002 (spu was stopped due to stop-and-signal)
* | 0x12340000 (the stop-and-signal code)
*/
printf("SPU Status: %#08x\n", spu_status);
exit(EXIT_SUCCESS); }
2023-02-08 | Linux man-pages 6.03 |