.. SPDX-License-Identifier: GPL-2.0
=======
spu_run
=======
Name
====
spu_run - execute an spu context
Synopsis
========
::
#include <sys/spu.h>
int spu_run(int fd, unsigned int *npc, unsigned int *event);
Description
===========
The spu_run system call is used on PowerPC machines that implement the
Cell Broadband Engine Architecture in order to access Synergistic Pro-
cessor Units (SPUs). It uses the fd that was returned from spu_cre-
ate(2) to address a specific SPU context. When the context gets sched-
uled to a physical SPU, it starts execution at the instruction pointer
passed in npc.
Execution of SPU code happens synchronously, meaning that spu_run does
not return while the SPU is still running. If there is a need to exe-
cute SPU code in parallel with other code on either the main CPU or
other SPUs, you need to create a new thread of execution first, e.g.
using the pthread_create(3) call.
When spu_run returns, the current value of the SPU instruction pointer
is written back to npc, so you can call spu_run again without updating
the pointers.
event can be a NULL pointer or point to an extended status code that
gets filled when spu_run returns. It can be one of the following con-
stants:
SPE_EVENT_DMA_ALIGNMENT
A DMA alignment error
SPE_EVENT_SPE_DATA_SEGMENT
A DMA segmentation error
SPE_EVENT_SPE_DATA_STORAGE
A DMA storage error
If NULL is passed as the event argument, these errors will result in a
signal delivered to the calling process.
Return Value
============
spu_run returns the value of the spu_status register or -1 to indicate
an error and set errno to one of the error codes listed below. The
spu_status register value contains 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 stop-and-signal.
0x04
SPU was stopped by halt.
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
stop-and-signal.
There are always one or more of the lower eight bits set or an error
code is returned from spu_run.
Errors
======
EAGAIN or EWOULDBLOCK
fd is in non-blocking mode and spu_run would block.
EBADF fd is not a valid file descriptor.
EFAULT npc is not a valid pointer or status is neither NULL nor a valid
pointer.
EINTR A signal occurred while spu_run was in progress. The npc value
has been updated to the new program counter value if necessary.
EINVAL fd is not a file descriptor returned from spu_create(2).
ENOMEM Insufficient memory was available to handle a page fault result-
ing from an 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.
Notes
=====
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 rec-
ommended libraries.
Conforming to
=============
This call is Linux specific and only implemented by the ppc64 architec-
ture. Programs using this system call are not portable.
Bugs
====
The code does not yet fully implement all features lined out here.
Author
======
Arnd Bergmann <arndb@de.ibm.com>
See Also
========
capabilities(7), close(2), spu_create(2), spufs(7)