alistair23-linux/arch/openrisc
Frederic Weisbecker 2bbb6817c0 nohz: Allow rcu extended quiescent state handling seperately from tick stop
It is assumed that rcu won't be used once we switch to tickless
mode and until we restart the tick. However this is not always
true, as in x86-64 where we dereference the idle notifiers after
the tick is stopped.

To prepare for fixing this, add two new APIs:
tick_nohz_idle_enter_norcu() and tick_nohz_idle_exit_norcu().

If no use of RCU is made in the idle loop between
tick_nohz_enter_idle() and tick_nohz_exit_idle() calls, the arch
must instead call the new *_norcu() version such that the arch doesn't
need to call rcu_idle_enter() and rcu_idle_exit().

Otherwise the arch must call tick_nohz_enter_idle() and
tick_nohz_exit_idle() and also call explicitly:

- rcu_idle_enter() after its last use of RCU before the CPU is put
to sleep.
- rcu_idle_exit() before the first use of RCU after the CPU is woken
up.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: David Miller <davem@davemloft.net>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-12-11 10:31:36 -08:00
..
boot OpenRISC: Build infrastructure 2011-07-22 18:46:30 +02:00
configs OpenRISC: Build infrastructure 2011-07-22 18:46:30 +02:00
include/asm doc: fix broken references 2011-09-27 18:08:04 +02:00
kernel nohz: Allow rcu extended quiescent state handling seperately from tick stop 2011-12-11 10:31:36 -08:00
lib OpenRISC: Library routines 2011-07-22 18:46:40 +02:00
mm OpenRISC: Build infrastructure 2011-07-22 18:46:30 +02:00
Kconfig Merge branch 'trivial' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild 2011-11-06 18:54:53 -08:00
Makefile OpenRISC: Build infrastructure 2011-07-22 18:46:30 +02:00
README.openrisc OpenRISC: Miscellaneous 2011-07-22 18:46:41 +02:00
TODO.openrisc OpenRISC: Miscellaneous 2011-07-22 18:46:41 +02:00

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