.\" Copyright (c) International Business Machines Corp., 2006 .\" .\" SPDX-License-Identifier: GPL-2.0-or-later .\" .\" HISTORY: .\" 2005-09-28, created by Arnd Bergmann .\" 2006-06-16, revised by Eduardo M. Fleury .\" 2007-07-10, some polishing by mtk .\" 2007-09-28, updates for newer kernels by Jeremy Kerr .\" .TH spu_create 2 2023-03-30 "Linux man-pages 6.04" .SH NAME spu_create \- create a new spu context .SH LIBRARY Standard C library .RI ( libc ", " \-lc ) .SH SYNOPSIS .nf .BR "#include " " /* Definition of " SPU_* " constants */" .BR "#include " " /* Definition of " SYS_* " constants */" .B #include .PP .BI "int syscall(SYS_spu_create, const char *" pathname \ ", unsigned int " flags , .BI " mode_t " mode ", int " neighbor_fd ); .fi .PP .IR Note : glibc provides no wrapper for .BR spu_create (), necessitating the use of .BR syscall (2). .SH DESCRIPTION The .BR spu_create () system call is used on PowerPC machines that implement the Cell Broadband Engine Architecture in order to access Synergistic Processor Units (SPUs). It creates a new logical context for an SPU in .I pathname and returns a file descriptor associated with it. .I pathname must refer to a nonexistent directory in the mount point of the SPU filesystem .RB ( spufs ). If .BR spu_create () is successful, a directory is created at .I pathname and it is populated with the files described in .BR spufs (7). .PP When a context is created, the returned file descriptor can only be passed to .BR spu_run (2), used as the .I dirfd argument to the .B *at family of system calls (e.g., .BR openat (2)), or closed; other operations are not defined. A logical SPU context is destroyed (along with all files created within the context's .I pathname directory) once the last reference to the context has gone; this usually occurs when the file descriptor returned by .BR spu_create () is closed. .PP The .I mode argument (minus any bits set in the process's .BR umask (2)) specifies the permissions used for creating the new directory in .BR spufs . See .BR stat (2) for a full list of the possible .I mode values. .PP The .I neighbor_fd is used only when the .B SPU_CREATE_AFFINITY_SPU flag is specified; see below. .PP The .I flags argument can be zero or any bitwise OR-ed combination of the following constants: .TP .B SPU_CREATE_EVENTS_ENABLED Rather than using signals for reporting DMA errors, use the .I event argument to .BR spu_run (2). .TP .B SPU_CREATE_GANG Create an SPU gang instead of a context. (A gang is a group of SPU contexts that are functionally related to each other and which share common scheduling parameters\[em]priority and policy. In the future, gang scheduling may be implemented causing the group to be switched in and out as a single unit.) .IP A new directory will be created at the location specified by the .I pathname argument. This gang may be used to hold other SPU contexts, by providing a pathname that is within the gang directory to further calls to .BR spu_create (). .TP .B SPU_CREATE_NOSCHED Create a context that is not affected by the SPU scheduler. Once the context is run, it will not be scheduled out until it is destroyed by the creating process. .IP Because the context cannot be removed from the SPU, some functionality is disabled for .B SPU_CREATE_NOSCHED contexts. Only a subset of the files will be available in this context directory in .BR spufs . Additionally, .B SPU_CREATE_NOSCHED contexts cannot dump a core file when crashing. .IP Creating .B SPU_CREATE_NOSCHED contexts requires the .B CAP_SYS_NICE capability. .TP .B SPU_CREATE_ISOLATE Create an isolated SPU context. Isolated contexts are protected from some PPE (PowerPC Processing Element) operations, such as access to the SPU local store and the NPC register. .IP Creating .B SPU_CREATE_ISOLATE contexts also requires the .B SPU_CREATE_NOSCHED flag. .TP .BR SPU_CREATE_AFFINITY_SPU " (since Linux 2.6.23)" .\" commit 8e68e2f248332a9c3fd4f08258f488c209bd3e0c Create a context with affinity to another SPU context. This affinity information is used within the SPU scheduling algorithm. Using this flag requires that a file descriptor referring to the other SPU context be passed in the .I neighbor_fd argument. .TP .BR SPU_CREATE_AFFINITY_MEM " (since Linux 2.6.23)" .\" commit 8e68e2f248332a9c3fd4f08258f488c209bd3e0c Create a context with affinity to system memory. This affinity information is used within the SPU scheduling algorithm. .SH RETURN VALUE On success, .BR spu_create () returns a new file descriptor. On failure, \-1 is returned, and .I errno is set to indicate the error. .SH ERRORS .TP .B EACCES The current user does not have write access to the .BR spufs (7) mount point. .TP .B EEXIST An SPU context already exists at the given pathname. .TP .B EFAULT .I pathname is not a valid string pointer in the calling process's address space. .TP .B EINVAL .I pathname is not a directory in the .BR spufs (7) mount point, or invalid flags have been provided. .TP .B ELOOP Too many symbolic links were found while resolving .IR pathname . .TP .B EMFILE The per-process limit on the number of open file descriptors has been reached. .TP .B ENAMETOOLONG .I pathname is too long. .TP .B ENFILE The system-wide limit on the total number of open files has been reached. .TP .B ENODEV An isolated context was requested, but the hardware does not support SPU isolation. .TP .B ENOENT Part of .I pathname could not be resolved. .TP .B ENOMEM The kernel could not allocate all resources required. .TP .B ENOSPC There are not enough SPU resources available to create a new context or the user-specific limit for the number of SPU contexts has been reached. .TP .B 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. .TP .B ENOTDIR A part of .I pathname is not a directory. .TP .B EPERM The .B SPU_CREATE_NOSCHED flag has been given, but the user does not have the .B CAP_SYS_NICE capability. .SH FILES .I pathname must point to a location beneath the mount point of .BR spufs . By convention, it gets mounted in .IR /spu . .SH STANDARDS Linux on PowerPC. .SH HISTORY Linux 2.6.16. .PP Prior to the addition of the .B SPU_CREATE_AFFINITY_SPU flag in Linux 2.6.23, the .BR spu_create () system call took only three arguments (i.e., there was no .I neighbor_fd argument). .SH NOTES .BR spu_create () is meant to be used from libraries that implement a more abstract interface to SPUs, not to be used from regular applications. See .UR http://www.bsc.es\:/projects\:/deepcomputing\:/linuxoncell/ .UE for the recommended libraries. .SH EXAMPLES See .BR spu_run (2) for an example of the use of .BR spu_create () .SH SEE ALSO .BR close (2), .BR spu_run (2), .BR capabilities (7), .BR spufs (7)