[PATCH] spufs: The SPU file system, base (67207b96) · Commits · 戴 / test

Documentation/filesystems/spufs.txt

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		SPUFS(2) Linux Programmer's Manual SPUFS(2)



		NAME
		spufs - the SPU file system


		DESCRIPTION
		The SPU file system is used on PowerPC machines that implement the Cell
		Broadband Engine Architecture in order to access Synergistic Processor
		Units (SPUs).

		The file system provides a name space similar to posix shared memory or
		message queues. Users that have write permissions on the file system
		can use spu_create(2) to establish SPU contexts in the spufs root.

		Every SPU context is represented by a directory containing a predefined
		set of files. These files can be used for manipulating the state of the
		logical SPU. Users can change permissions on those files, but not actu-
		ally add or remove files.


		MOUNT OPTIONS
		uid=<uid>
		set the user owning the mount point, the default is 0 (root).

		gid=<gid>
		set the group owning the mount point, the default is 0 (root).


		FILES
		The files in spufs mostly follow the standard behavior for regular sys-
		tem calls like read(2) or write(2), but often support only a subset of
		the operations supported on regular file systems. This list details the
		supported operations and the deviations from the behaviour in the
		respective man pages.

		All files that support the read(2) operation also support readv(2) and
		all files that support the write(2) operation also support writev(2).
		All files support the access(2) and stat(2) family of operations, but
		only the st_mode, st_nlink, st_uid and st_gid fields of struct stat
		contain reliable information.

		All files support the chmod(2)/fchmod(2) and chown(2)/fchown(2) opera-
		tions, but will not be able to grant permissions that contradict the
		possible operations, e.g. read access on the wbox file.

		The current set of files is:


		/mem
		the contents of the local storage memory of the SPU. This can be
		accessed like a regular shared memory file and contains both code and
		data in the address space of the SPU. The possible operations on an
		open mem file are:

		read(2), pread(2), write(2), pwrite(2), lseek(2)
		These operate as documented, with the exception that seek(2),
		write(2) and pwrite(2) are not supported beyond the end of the
		file. The file size is the size of the local storage of the SPU,
		which normally is 256 kilobytes.

		mmap(2)
		Mapping mem into the process address space gives access to the
		SPU local storage within the process address space. Only
		MAP_SHARED mappings are allowed.


		/mbox
		The first SPU to CPU communication mailbox. This file is read-only and
		can be read in units of 32 bits. The file can only be used in non-
		blocking mode and it even poll() will not block on it. The possible
		operations on an open mbox file are:

		read(2)
		If a count smaller than four is requested, read returns -1 and
		sets errno to EINVAL. If there is no data available in the mail
		box, the return value is set to -1 and errno becomes EAGAIN.
		When data has been read successfully, four bytes are placed in
		the data buffer and the value four is returned.


		/ibox
		The second SPU to CPU communication mailbox. This file is similar to
		the first mailbox file, but can be read in blocking I/O mode, and the
		poll familiy of system calls can be used to wait for it. The possible
		operations on an open ibox file are:

		read(2)
		If a count smaller than four is requested, read returns -1 and
		sets errno to EINVAL. If there is no data available in the mail
		box and the file descriptor has been opened with O_NONBLOCK, the
		return value is set to -1 and errno becomes EAGAIN.

		If there is no data available in the mail box and the file
		descriptor has been opened without O_NONBLOCK, the call will
		block until the SPU writes to its interrupt mailbox channel.
		When data has been read successfully, four bytes are placed in
		the data buffer and the value four is returned.

		poll(2)
		Poll on the ibox file returns (POLLIN \| POLLRDNORM) whenever
		data is available for reading.


		/wbox
		The CPU to SPU communation mailbox. It is write-only can can be written
		in units of 32 bits. If the mailbox is full, write() will block and
		poll can be used to wait for it becoming empty again. The possible
		operations on an open wbox file are: write(2) If a count smaller than
		four is requested, write returns -1 and sets errno to EINVAL. If there
		is no space available in the mail box and the file descriptor has been
		opened with O_NONBLOCK, the return value is set to -1 and errno becomes
		EAGAIN.

		If there is no space available in the mail box and the file descriptor
		has been opened without O_NONBLOCK, the call will block until the SPU
		reads from its PPE mailbox channel. When data has been read success-
		fully, four bytes are placed in the data buffer and the value four is
		returned.

		poll(2)
		Poll on the ibox file returns (POLLOUT \| POLLWRNORM) whenever
		space is available for writing.


		/mbox_stat
		/ibox_stat
		/wbox_stat
		Read-only files that contain the length of the current queue, i.e. how
		many words can be read from mbox or ibox or how many words can be
		written to wbox without blocking. The files can be read only in 4-byte
		units and return a big-endian binary integer number. The possible
		operations on an open *box_stat file are:

		read(2)
		If a count smaller than four is requested, read returns -1 and
		sets errno to EINVAL. Otherwise, a four byte value is placed in
		the data buffer, containing the number of elements that can be
		read from (for mbox_stat and ibox_stat) or written to (for
		wbox_stat) the respective mail box without blocking or resulting
		in EAGAIN.


		/npc
		/decr
		/decr_status
		/spu_tag_mask
		/event_mask
		/srr0
		Internal registers of the SPU. The representation is an ASCII string
		with the numeric value of the next instruction to be executed. These
		can be used in read/write mode for debugging, but normal operation of
		programs should not rely on them because access to any of them except
		npc requires an SPU context save and is therefore very inefficient.

		The contents of these files are:

		npc Next Program Counter

		decr SPU Decrementer

		decr_status Decrementer Status

		spu_tag_mask MFC tag mask for SPU DMA

		event_mask Event mask for SPU interrupts

		srr0 Interrupt Return address register


		The possible operations on an open npc, decr, decr_status,
		spu_tag_mask, event_mask or srr0 file are:

		read(2)
		When the count supplied to the read call is shorter than the
		required length for the pointer value plus a newline character,
		subsequent reads from the same file descriptor will result in
		completing the string, regardless of changes to the register by
		a running SPU task. When a complete string has been read, all
		subsequent read operations will return zero bytes and a new file
		descriptor needs to be opened to read the value again.

		write(2)
		A write operation on the file results in setting the register to
		the value given in the string. The string is parsed from the
		beginning to the first non-numeric character or the end of the
		buffer. Subsequent writes to the same file descriptor overwrite
		the previous setting.


		/fpcr
		This file gives access to the Floating Point Status and Control Regis-
		ter as a four byte long file. The operations on the fpcr file are:

		read(2)
		If a count smaller than four is requested, read returns -1 and
		sets errno to EINVAL. Otherwise, a four byte value is placed in
		the data buffer, containing the current value of the fpcr regis-
		ter.

		write(2)
		If a count smaller than four is requested, write returns -1 and
		sets errno to EINVAL. Otherwise, a four byte value is copied
		from the data buffer, updating the value of the fpcr register.


		/signal1
		/signal2
		The two signal notification channels of an SPU. These are read-write
		files that operate on a 32 bit word. Writing to one of these files
		triggers an interrupt on the SPU. The value writting to the signal
		files can be read from the SPU through a channel read or from host user
		space through the file. After the value has been read by the SPU, it
		is reset to zero. The possible operations on an open signal1 or sig-
		nal2 file are:

		read(2)
		If a count smaller than four is requested, read returns -1 and
		sets errno to EINVAL. Otherwise, a four byte value is placed in
		the data buffer, containing the current value of the specified
		signal notification register.

		write(2)
		If a count smaller than four is requested, write returns -1 and
		sets errno to EINVAL. Otherwise, a four byte value is copied
		from the data buffer, updating the value of the specified signal
		notification register. The signal notification register will
		either be replaced with the input data or will be updated to the
		bitwise OR or the old value and the input data, depending on the
		contents of the signal1_type, or signal2_type respectively,
		file.


		/signal1_type
		/signal2_type
		These two files change the behavior of the signal1 and signal2 notifi-
		cation files. The contain a numerical ASCII string which is read as
		either "1" or "0". In mode 0 (overwrite), the hardware replaces the
		contents of the signal channel with the data that is written to it. in
		mode 1 (logical OR), the hardware accumulates the bits that are subse-
		quently written to it. The possible operations on an open signal1_type
		or signal2_type file are:

		read(2)
		When the count supplied to the read call is shorter than the
		required length for the digit plus a newline character, subse-
		quent reads from the same file descriptor will result in com-
		pleting the string. When a complete string has been read, all
		subsequent read operations will return zero bytes and a new file
		descriptor needs to be opened to read the value again.

		write(2)
		A write operation on the file results in setting the register to
		the value given in the string. The string is parsed from the
		beginning to the first non-numeric character or the end of the
		buffer. Subsequent writes to the same file descriptor overwrite
		the previous setting.


		EXAMPLES
		/etc/fstab entry
		none /spu spufs gid=spu 0 0


		AUTHORS
		Arnd Bergmann <arndb@de.ibm.com>, Mark Nutter <mnutter@us.ibm.com>,
		Ulrich Weigand <Ulrich.Weigand@de.ibm.com>

		SEE ALSO
		capabilities(7), close(2), spu_create(2), spu_run(2), spufs(7)



		Linux 2005-09-28 SPUFS(2)

		------------------------------------------------------------------------------

		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);

		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 occured 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)



		Linux 2005-09-28 SPU_RUN(2)

		------------------------------------------------------------------------------

		SPU_CREATE(2) Linux Programmer's Manual SPU_CREATE(2)



		NAME
		spu_create - create a new spu context


		SYNOPSIS
		#include <sys/types.h>
		#include <sys/spu.h>

		int spu_create(const char *pathname, int flags, mode_t mode);

		DESCRIPTION
		The 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
		pathname and returns a handle to associated with it. pathname must
		point to a non-existing directory in the mount point of the SPU file
		system (spufs). When spu_create is successful, a directory gets cre-
		ated on pathname and it is populated with files.

		The returned file handle can only be passed to spu_run(2) or closed,
		other operations are not defined on it. When it is closed, all associ-
		ated directory entries in spufs are removed. When the last file handle
		pointing either inside of the context directory or to this file
		descriptor is closed, the logical SPU context is destroyed.

		The parameter flags can be zero or any bitwise or'd combination of the
		following constants:

		SPU_RAWIO
		Allow mapping of some of the hardware registers of the SPU into
		user space. This flag requires the CAP_SYS_RAWIO capability, see
		capabilities(7).

		The mode parameter specifies the permissions used for creating the new
		directory in spufs. mode is modified with the user's umask(2) value
		and then used for both the directory and the files contained in it. The
		file permissions mask out some more bits of mode because they typically
		support only read or write access. See stat(2) for a full list of the
		possible mode values.


		RETURN VALUE
		spu_create returns a new file descriptor. It may return -1 to indicate
		an error condition and set errno to one of the error codes listed
		below.


		ERRORS
		EACCESS
		The current user does not have write access on the spufs mount
		point.

		EEXIST An SPU context already exists at the given path name.

		EFAULT pathname is not a valid string pointer in the current address
		space.

		EINVAL pathname is not a directory in the spufs mount point.

		ELOOP Too many symlinks were found while resolving pathname.

		EMFILE The process has reached its maximum open file limit.

		ENAMETOOLONG
		pathname was too long.

		ENFILE The system has reached the global open file limit.

		ENOENT Part of pathname could not be resolved.

		ENOMEM The kernel could not allocate all resources required.

		ENOSPC There are not enough SPU resources available to create a new
		context or the user specific limit for the number of SPU con-
		texts has been reached.

		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.

		ENOTDIR
		A part of pathname is not a directory.



		NOTES
		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 http://www.bsc.es/projects/deepcomputing/linuxoncell/ for the rec-
		ommended libraries.


		FILES
		pathname must point to a location beneath the mount point of spufs. By
		convention, it gets mounted in /spu.


		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_run(2), spufs(7)



		Linux 2005-09-28 SPU_CREATE(2)

arch/powerpc/Kconfig

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Original line number	Diff line number	Diff line
		@@ -482,6 +482,7 @@ source arch/powerpc/platforms/embedded6xx/Kconfig
		source arch/powerpc/platforms/4xx/Kconfig
		source arch/powerpc/platforms/85xx/Kconfig
		source arch/powerpc/platforms/8xx/Kconfig
		source arch/powerpc/platforms/cell/Kconfig

		menu "Kernel options"

arch/powerpc/kernel/systbl.S

+2 −0

Original line number	Diff line number	Diff line
		@@ -319,3 +319,5 @@ COMPAT_SYS(ioprio_get)
		SYSCALL(inotify_init)
		SYSCALL(inotify_add_watch)
		SYSCALL(inotify_rm_watch)
		SYSCALL(spu_run)
		SYSCALL(spu_create)

arch/powerpc/mm/hash_utils_64.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -644,6 +644,7 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
		DBG_LOW(" -> rc=%d\n", rc);
		return rc;
		}
		EXPORT_SYMBOL_GPL(hash_page);

		void hash_preload(struct mm_struct *mm, unsigned long ea,
		unsigned long access, unsigned long trap)

arch/powerpc/platforms/cell/Kconfig

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		menu "Cell Broadband Engine options"
		depends on PPC_CELL

		config SPU_FS
		tristate "SPU file system"
		default m
		depends on PPC_CELL
		help
		The SPU file system is used to access Synergistic Processing
		Units on machines implementing the Broadband Processor
		Architecture.

		endmenu

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