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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | STANDARDS | HISTORY | NOTES | EXAMPLES | SEE ALSO |
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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:
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.
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:
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.
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.
Linux on PowerPC.
Linux 2.6.16.
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);
}
close(2), spu_create(2), capabilities(7), spufs(7)
Linux man-pages (unreleased) (date) spu_run(2)
Pages that refer to this page: spu_create(2), syscalls(2), spufs(7)
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HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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