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Davidlohr Bueso 3a6bfbc91d arch, locking: Ciao arch_mutex_cpu_relax() 
The arch_mutex_cpu_relax() function, introduced by 34b133f, is
hacky and ugly. It was added a few years ago to address the fact
that common cpu_relax() calls include yielding on s390, and thus
impact the optimistic spinning functionality of mutexes. Nowadays
we use this function well beyond mutexes: rwsem, qrwlock, mcs and
lockref. Since the macro that defines the call is in the mutex header,
any users must include mutex.h and the naming is misleading as well.

This patch (i) renames the call to cpu_relax_lowlatency  ("relax, but
only if you can do it with very low latency") and (ii) defines it in
each arch's asm/processor.h local header, just like for regular cpu_relax
functions. On all archs, except s390, cpu_relax_lowlatency is simply cpu_relax,
and thus we can take it out of mutex.h. While this can seem redundant,
I believe it is a good choice as it allows us to move out arch specific
logic from generic locking primitives and enables future(?) archs to
transparently define it, similarly to System Z.

Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Anton Blanchard <anton@samba.org>
Cc: Aurelien Jacquiot <a-jacquiot@ti.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Bharat Bhushan <r65777@freescale.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen Liqin <liqin.linux@gmail.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Howells <dhowells@redhat.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
Cc: Dominik Dingel <dingel@linux.vnet.ibm.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Joe Perches <joe@perches.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Joseph Myers <joseph@codesourcery.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com>
Cc: Lennox Wu <lennox.wu@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Salter <msalter@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Nicolas Pitre <nico@linaro.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Qais Yousef <qais.yousef@imgtec.com>
Cc: Qiaowei Ren <qiaowei.ren@intel.com>
Cc: Rafael Wysocki <rafael.j.wysocki@intel.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Steven Miao <realmz6@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Stratos Karafotis <stratosk@semaphore.gr>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vasily Kulikov <segoon@openwall.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Cc: Waiman Long <Waiman.Long@hp.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Wolfram Sang <wsa@the-dreams.de>
Cc: adi-buildroot-devel@lists.sourceforge.net
Cc: linux390@de.ibm.com
Cc: linux-alpha@vger.kernel.org
Cc: linux-am33-list@redhat.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-cris-kernel@axis.com
Cc: linux-hexagon@vger.kernel.org
Cc: linux-ia64@vger.kernel.org
Cc: linux@lists.openrisc.net
Cc: linux-m32r-ja@ml.linux-m32r.org
Cc: linux-m32r@ml.linux-m32r.org
Cc: linux-m68k@lists.linux-m68k.org
Cc: linux-metag@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-s390@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Cc: linux-xtensa@linux-xtensa.org
Cc: sparclinux@vger.kernel.org
Link: http://lkml.kernel.org/r/1404079773.2619.4.camel@buesod1.americas.hpqcorp.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 		2014-07-17 12:32:47 +02:00
..
boot/dts openrisc: use new common dtc rule 2012-12-03 17:17:48 -06:00
configs openrisc: Refresh or1ksim_defconfig for v3.12 2013-11-15 10:37:32 +01:00
include arch, locking: Ciao arch_mutex_cpu_relax() 2014-07-17 12:32:47 +02:00
kernel of/fdt: consolidate built-in dtb section variables 2014-04-30 00:59:13 -05:00
lib ARCH: drivers remove __dev* attributes. 2013-01-03 15:57:13 -08:00
mm arch: mm: pass userspace fault flag to generic fault handler 2013-09-12 15:38:01 -07:00
Kconfig Kconfig: rename HAS_IOPORT to HAS_IOPORT_MAP 2014-04-07 16:36:11 -07:00
Makefile openrisc: Makefile: append "-D__linux__" to KBUILD_CFLAGS 2013-11-05 16:14:47 +01:00
README.openrisc OpenRISC: Miscellaneous 2011-07-22 18:46:41 +02:00
TODO.openrisc OpenRISC: Miscellaneous 2011-07-22 18:46:41 +02:00

README.openrisc 

OpenRISC Linux
==============

This is a port of Linux to the OpenRISC class of microprocessors; the initial
target architecture, specifically, is the 32-bit OpenRISC 1000 family (or1k).

For information about OpenRISC processors and ongoing development:

	website		http://openrisc.net

For more information about Linux on OpenRISC, please contact South Pole AB.

	email:		info@southpole.se

	website:	http://southpole.se
			http://southpoleconsulting.com

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

Build instructions for OpenRISC toolchain and Linux
===================================================

In order to build and run Linux for OpenRISC, you'll need at least a basic
toolchain and, perhaps, the architectural simulator.  Steps to get these bits
in place are outlined here.

1)  The toolchain can be obtained from openrisc.net.  Instructions for building
a toolchain can be found at:

http://openrisc.net/toolchain-build.html

2) or1ksim (optional)

or1ksim is the architectural simulator which will allow you to actually run
your OpenRISC Linux kernel if you don't have an OpenRISC processor at hand.

	git clone git://openrisc.net/jonas/or1ksim-svn

	cd or1ksim
	./configure --prefix=$OPENRISC_PREFIX
	make
	make install

3)  Linux kernel

Build the kernel as usual

	make ARCH=openrisc defconfig
	make ARCH=openrisc

4)  Run in architectural simulator

Grab the or1ksim platform configuration file (from the or1ksim source) and
together with your freshly built vmlinux, run your kernel with the following
incantation:

	sim -f arch/openrisc/or1ksim.cfg vmlinux

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

Terminology
===========

In the code, the following particles are used on symbols to limit the scope
to more or less specific processor implementations:

openrisc: the OpenRISC class of processors
or1k:     the OpenRISC 1000 family of processors
or1200:   the OpenRISC 1200 processor

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

History
========

18. 11. 2003	Matjaz Breskvar (phoenix@bsemi.com)
	initial port of linux to OpenRISC/or32 architecture.
        all the core stuff is implemented and seams usable.

08. 12. 2003	Matjaz Breskvar (phoenix@bsemi.com)
	complete change of TLB miss handling.
	rewrite of exceptions handling.
	fully functional sash-3.6 in default initrd.
	a much improved version with changes all around.

10. 04. 2004	Matjaz Breskvar (phoenix@bsemi.com)
	alot of bugfixes all over.
	ethernet support, functional http and telnet servers.
	running many standard linux apps.

26. 06. 2004	Matjaz Breskvar (phoenix@bsemi.com)
	port to 2.6.x

30. 11. 2004	Matjaz Breskvar (phoenix@bsemi.com)
	lots of bugfixes and enhancments.
	added opencores framebuffer driver.

09. 10. 2010    Jonas Bonn (jonas@southpole.se)
	major rewrite to bring up to par with upstream Linux 2.6.36