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Provide documentation of the kernel-doc documentation conventions oriented
to kernel hackers.
Since I figure that there will be more people reading this
kernel-doc-nano-HOWTO.txt file who are kernel developers focused on the
rest of the kernel, than there will be readers of this file who are
documentation developers extracting that embedded kernel-doc
documentation, I have taken the liberty of making the new section added
here:
How to format kernel-doc comments
the first section of the kernel-doc-nano-HOWTO.txt file.
This first section is intended to introduce, motivate and provide basic
usage of the kernel-doc mechanism for kernel hackers developing other
portions of the kernel.
Signed-off-by: Paul Jackson <pj@sgi.com>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Although if people have questions about ARCnet, perhaps it's _better_
for them to be mailing dwmw2@cam.ac.uk about it...
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Update status and URL for the "Gary's Encyclopedia" entry.
Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Make the doc consistent with current cpusets implementation.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Acked-by: Paul Jackson <pj@sgi.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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* git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/v4l-dvb: (48 commits)
V4L/DVB (8001): dib0070: fix dib0070_attach when !CONFIG_DVB_TUNER_DIB0070
V4L/DVB (8000): tda827x: fix NULL pointer in tda827xa_lna_gain
V4L/DVB (7990): Fix entry for PowerColor RA 330 and make it run with firmware version 2.7
V4L/DVB (7983): tda18271_calc_rf_cal must return the return value of tda18271_lookup_map
V4L/DVB (7978): cx18: explicitly test for XC2028 tuner
V4L/DVB (7977): cx18: fix init order and remove duplicate open_on_first_use.
V4L/DVB (7975): saa7134_empress
V4L/DVB (7974): fix MEDIA_TUNER && FW_LOADER build error
V4L/DVB (7972): or51132.c: unaligned
V4L/DVB (7971): usb: unaligned
V4L/DVB (7970): mix trivial endianness annotations
V4L/DVB (7969): m920x: unaligned access
V4L/DVB (7968): zoran: endianness annotations
V4L/DVB (7967): bt8xx: unaligned access
V4L/DVB (7966): cx18: direct dereferencing of iomem
V4L/DVB (7965): annotate bcx_riscmem
V4L/DVB (7964): cx18 iomem annotations
V4L/DVB (7963): ivtv: trivial annotations
V4L/DVB (7962): ttusb endianness annotations and fixes
V4L/DVB (7961): fix endianness bug in dib0700_devices.c
...
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Suggest how to deal with patch modifications caused by
merging or back-porting when you're a maintainer.
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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firmware version 2.7
Signed-off-by: Daniel Gimpelevich <daniel@gimpelevich.san-francisco.ca.us>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
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I always assumed that the Compro H900 could do digital as well,
but it turned out that it is an analog-only card.
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
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This patch updates the URL of the bridge homepage.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This is the lguest implementation of the VIRTIO_F_NOTIFY_ON_EMPTY feature.
It is currently only published for network devices, but it is turned on for
everyone.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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This driver reads IBM Active Energy Manager energy/temperature/power
sensors on IBM System X hardware.
[akpm@linux-foundation.org: fix printk warnings]
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Cc: "Mark M. Hoffman" <mhoffman@lightlink.com>
Cc: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Fuse allocates a separate bdi for each filesystem, and registers them
in sysfs with "MAJOR:MINOR" of sb->s_dev (st_dev). This works fine for
anon devices normally used by fuse, but can conflict with an already
registered BDI for "fuseblk" filesystems, where sb->s_dev represents a
real block device. In particularl this happens if a non-partitioned
device is being mounted.
Fix by registering with a different name for "fuseblk" filesystems.
Thanks to Ioan Ionita for the bug report.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reported-by: Ioan Ionita <opslynx@gmail.com>
Tested-by: Ioan Ionita <opslynx@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq
* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq:
[CPUFREQ] clarify license of freq_table.c
[CPUFREQ] Remove documentation of removed ondemand tunable.
[CPUFREQ] Crusoe: longrun cpufreq module reports false min freq
[CPUFREQ] powernow-k8: improve error messages
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Add a chapter about trylock functions.
http://bugzilla.kernel.org/show_bug.cgi?id=9011
Signed-off-by: Matti Linnanvuori <mattilinnanvuori@yahoo.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (removed down_trylock)
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sampling_down_factor was removed in ccb2fe209dac9ff67f6351e783e610073afaaeaf
back in June 2006.
Signed-off-by: Dave Jones <davej@redhat.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux-2.6
* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux-2.6:
[IA64] fix personality(PER_LINUX32) performance issue
[IA64] Properly unregister legacy interrupts
[IA64] Remove NULL pointer check for argument never passed as NULL.
[IA64] trivial cleanup for perfmon.c
[IA64] trivial cleanup for entry.S
[IA64] fix interrupt masking for pending works on kernel leave
[IA64] allow user to force_pal_cache_flush
[IA64] Don't reserve crashkernel memory > 4 GB
[IA64] machvec support for SGI UV platform
[IA64] Add header files for SGI UV platform
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cio_msg= is gone, also remove it from kernel-parameters.txt.
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Schedule a removal for this driver. Alternative driver is available for
a while now.
Signed-off-by: Sebastian Siewior <bigeasy@linutronix.de>
Acked-by: Greg Ungerer <gerg@uclinux.org>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The sequence executed in check_sal_cache_flush:
- pend a timer interrupt
- call SAL_CACHE_FLUSH
- see if interrupt is still pending
can hang HP machines with buggy SAL_CACHE_FLUSH implementations.
Provide a kernel command-line argument to allow users skip this
check if desired. Using this parameter will force ia64_sal_cache_flush
to call ia64_pal_cache_flush() instead of SAL_CACHE_FLUSH.
Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
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* git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/v4l-dvb: (70 commits)
V4L/DVB (7900): pvrusb: Fix Kconfig if DVB=m V4L_core=y
V4L/DVB (7899): Fixes a few remaining Kbuild issues at common/tuners
V4L/DVB (7898): Fix VIDEO_MEDIA Kconfig logic
V4L/DVB (7895): tveeprom: update Hauppauge analog audio and video decoders
V4L/DVB (7893): xc5000: bug-fix: allow multiple devices in a single system
V4L/DVB (7891): cx18/ivtv: fix open() kernel oops
V4L/DVB (7890): cx18: removed bogus and confusing conditional
V4L/DVB (7889): cx18: improve HVR-1600 detection.
V4L/DVB (7888): cx18: minor card definition updates.
V4L/DVB (7887): cx18: fix Compro H900 analog support.
V4L/DVB (7881): saa7134: fixed a compile warning in saa7134-core.c
V4L/DVB (7880): saa7134: remove explicit GPIO initialization
V4L/DVB(7879): Adding cx18 Support for mxl5005s
V4L/DVB(7878): mxl55005s: Makefile and Kconfig additions
V4L/DVB(7877): mxl5005s: Ensure debug is off
V4L/DVB(7876): mxl5005s: Remove incorrect copyright holders
V4L/DVB(7875): mxl5005s: Remove redundant functions
V4L/DVB(7874): mxl5005s: Fix function statics
V4L/DVB(7873): mxl5005s: Fix header includes.
V4L/DVB(7872): mxl5005s: checkpatch.pl compliance
...
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read_barrie_depends has always been a noop (not a compiler barrier) on all
architectures except SMP alpha. This brings UP alpha and frv into line with all
other architectures, and fixes incorrect documentation.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
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Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
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Correct the cgroups documentation to reflect the correct file names.
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Cc: Sudhir Kumar <skumar@linux.vnet.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Add a sentence about when fan speed increases to maximum.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Attempt to make the documentation about the I2C/SMBus functionality
checking API clearer.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
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Improve the smbus-protocol documentation file somewhat:
- Use the names of the SMBus protocol operations (from the 2.0
specification), not made-up-for-Linux names.
- Add the name of the call used to execute each operation ... and
point out that there are mismatches, where functions execute
different protocol operations than their names specify.
The most confusing examples are that "Read Byte" isn't executed by
i2c_smbus_read_byte(), and that "Write Byte" isn't executed by
i2c_smbus_write_byte(). When coding, that's not as bad as it may
seem; but that case would seem to be worth fixing.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
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The only sporadically used CIO_DEBUG messages are replaced by ordinary
CIO_MSG_EVENT messages. The CIO_MSG_EVENT messages debug levels are
consolidated.
Signed-off-by: Michael Ernst <mernst@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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And with that last patch to affs killing the last put_inode instance we
can finally, after many years of transition kill this racy and awkward
interface.
(It's kinda funny that even the description in
Documentation/filesystems/vfs.txt was entirely wrong..)
Also remove a very misleading comment above the defintion of
struct super_operations.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched-fixes
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched-fixes:
sched: default to n for GROUP_SCHED and FAIR_GROUP_SCHED
sched: add optional support for CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
sched, x86: add HAVE_UNSTABLE_SCHED_CLOCK
sched: fix cpu clock
sched: fair-group: fix a Div0 error of the fair group scheduler
sched: fix missing locking in sched_domains code
sched: make clock sync tunable by architecture code
sched: fix debugging
sched: fix sched_info_switch not being called according to documentation
sched: fix hrtick_start_fair and CPU-Hotplug
sched: fix SCHED_FAIR wake-idle logic error
sched: fix RT task-wakeup logic
sched: add statics, don't return void expressions
sched: add debug checks to idle functions
sched: remove old sched doc
sched: make rt_sched_class, idle_sched_class static
sched: optimize calc_delta_mine()
sched: fix normalized sleeper
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Fabio Checconi noticed that Documentation/scheduler/sched-design.txt was
a stale copy of the old scheduler. Remove it.
Reported-by: Fabio Checconi <fabio@gandalf.sssup.it>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6:
x86 PCI: call dmi_check_pciprobe()
x86/pci: add pci=skip_isa_align command lines.
x86/pci: remove flag in pci_cfg_space_size_ext
x86: fix section mismatch in pci_scan_bus
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Remove the rest of the old mac_esp driver. Also ditch the rest of the
machw mechanism, it needs to be replaced by a fake openfirmware tree.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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so we don't align the io port start address for pci cards.
also move out dmi check out acpi.c, because it has nothing to do with acpi.
it could spare some calling when we have several peer root buses.
Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
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Two minor fixes to the kgdb documentation.
Signed-off-by: Grzegorz Chwesewicz, Chilan <grzegorz.chwesewicz@chilan.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
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For the use case the hint describe a simple dependency is
enough.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6:
slub: #ifdef simplification
slabinfo: Support printout of the number of fallbacks
slub: Whitespace cleanup and use of strict_strtoul
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* git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc:
[POWERPC] Bolt in SLB entry for kernel stack on secondary cpus
[POWERPC] PS3: Update ps3_defconfig
[POWERPC] PS3: Remove unsupported wakeup sources
[POWERPC] PS3: Make ps3_virq_setup and ps3_virq_destroy static
[POWERPC] PS3: Add time include to lpm
[POWERPC] Fix slb.c compile warnings
[POWERPC] Xilinx: Fix compile warnings
[POWERPC] Squash build warning for print of resource_size_t in fsl_soc.c
[RAPIDIO] fix current kernel-doc notation
[POWERPC] 86xx: mpc8610_hpcd: add support for PCI Express x8 slot
Fix a potential issue in mpc52xx uart driver
[POWERPC] mpc5200: Allow for fixed speed MII configurations
[POWERPC] 86xx: Fix the wrong serial1 interrupt for 8610 board
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* git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6:
[SCSI] aic94xx: fix section mismatch
[SCSI] u14-34f: Fix 32bit only problem
[SCSI] dpt_i2o: sysfs code
[SCSI] dpt_i2o: 64 bit support
[SCSI] dpt_i2o: move from virt_to_bus/bus_to_virt to dma_alloc_coherent
[SCSI] dpt_i2o: use standard __init / __exit code
[SCSI] megaraid_sas: fix suspend/resume sections
[SCSI] aacraid: Add Power Management support
[SCSI] aacraid: Fix jbod operations scan issues
[SCSI] aacraid: Fix warning about macro side-effects
[SCSI] add support for variable length extended commands
[SCSI] Let scsi_cmnd->cmnd use request->cmd buffer
[SCSI] bsg: add large command support
[SCSI] aacraid: Fix down_interruptible() to check the return value correctly
[SCSI] megaraid_sas; Update the Version and Changelog
[SCSI] ibmvscsi: Handle non SCSI error status
[SCSI] bug fix for free list handling
[SCSI] ipr: Rename ipr's state scsi host attribute to prevent collisions
[SCSI] megaraid_mbox: fix Dell CERC firmware problem
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This brings us closer to Real Life, where we'd examine the device
features once it's set the DRIVER_OK status bit.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Ron Minnich points out that a struct containing a char is not always
sizeof(char); simplest to remove the structure to avoid confusion.
Cc: "ron minnich" <rminnich@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Add functionality to slabinfo to print out the number of fallbacks
that have occurred for each slab cache when the -D option is specified.
Also widen the allocation / free field since the numbers became
too big after a week.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
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Various improvements for configuring the MPC5200 MII link from the
device tree:
* Look for 'current-speed' property for fixed speed MII links
* Look for 'fsl,7-wire-mode' property for boards using the 7 wire mode
* move definition of private data structure out of the header file
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Wolfgang Grandegger <wg@grandegger.com>
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* 'release' of git://lm-sensors.org/kernel/mhoffman/hwmon-2.6:
hwmon: (adt7473) minor cleanup / refactoring
hwmon: (asb100) Remove some dead code
hwmon: (lm75) Fix an incorrect comment
hwmon: (w83793) VID and VRM handling cleanups
hwmon: (w83l785ts) Don't ask the user to report failures
hwmon: (smsc47b397) add a new chip id (0x8c)
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The extended crashkernel syntax is a little confusing in the way it handles
ranges. eg:
crashkernel=512M-2G:64M,2G-:128M
Means if the machine has between 512M and 2G of memory the crash region should
be 64M, and if the machine has 2G of memory the region should be 64M. Only if
the machine has more than 2G memory will 128M be allocated.
Although that semantic is correct, it is somewhat baffling. Instead I propose
that the end of the range means the first address past the end of the range,
ie: 512M up to but not including 2G.
[bwalle@suse.de: clarify inclusive/exclusive in crashkernel commandline in documentation]
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Acked-by: Bernhard Walle <bwalle@suse.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Simon Horman <horms@verge.net.au>
Signed-off-by: Bernhard Walle <bwalle@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6
* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6: (179 commits)
ACPI: Fix acpi_processor_idle and idle= boot parameters interaction
acpi: fix section mismatch warning in pnpacpi
intel_menlo: fix build warning
ACPI: Cleanup: Remove unneeded, multiple local dummy variables
ACPI: video - fix permissions on some proc entries
ACPI: video - properly handle errors when registering proc elements
ACPI: video - do not store invalid entries in attached_array list
ACPI: re-name acpi_pm_ops to acpi_suspend_ops
ACER_WMI/ASUS_LAPTOP: fix build bug
thinkpad_acpi: fix possible NULL pointer dereference if kstrdup failed
ACPI: check a return value correctly in acpi_power_get_context()
#if 0 acpi/bay.c:eject_removable_drive()
eeepc-laptop: add hwmon fan control
eeepc-laptop: add backlight
eeepc-laptop: add base driver
ACPI: thinkpad-acpi: bump up version to 0.20
ACPI: thinkpad-acpi: fix selects in Kconfig
ACPI: thinkpad-acpi: use a private workqueue
ACPI: thinkpad-acpi: fluff really minor fix
ACPI: thinkpad-acpi: use uppercase for "LED" on user documentation
...
Fixed conflicts in drivers/acpi/video.c and drivers/misc/intel_menlow.c
manually.
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'bugzilla-9916', 'ec', 'eeepc', 'idle', 'misc', 'pm-legacy', 'sysfs-links-2.6.26', 'thermal', 'thinkpad' and 'video' into release
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git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc
* 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc:
[POWERPC] Fix crashkernel= handling when no crashkernel= specified
[POWERPC] Make emergency stack safe for current_thread_info() use
[POWERPC] spufs: add .gitignore for spu_save_dump.h & spu_restore_dump.h
[POWERPC] spufs: trace spu_acquire_saved events
[POWERPC] spufs: fix marker name for find_victim
[POWERPC] spufs: add marker for destroy_spu_context
[POWERPC] spufs: add sputrace marker parameter names
[POWERPC] spufs: add context switch notification log
[POWERPC] mpc5200: defconfigs for CM5200, Lite5200B, Motion-PRO and TQM5200
[POWERPC] mpc5200: Switch mpc5200 dts files to dts-v1 format
[POWERPC] mpc5200: Fix FEC error handling on FIFO errors
[POWERPC] mpc5200: add Phytec pcm030 board support
[POWERPC] mpc5200: add gpiolib support for mpc5200
[POWERPC] mpc5200: add interrupt type function
[POWERPC] mpc5200: Fix unterminated of_device_id table
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Add a DocBook for debugobjects.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Greg KH <greg@kroah.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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We can see an ever repeating problem pattern with objects of any kind in the
kernel:
1) freeing of active objects
2) reinitialization of active objects
Both problems can be hard to debug because the crash happens at a point where
we have no chance to decode the root cause anymore. One problem spot are
kernel timers, where the detection of the problem often happens in interrupt
context and usually causes the machine to panic.
While working on a timer related bug report I had to hack specialized code
into the timer subsystem to get a reasonable hint for the root cause. This
debug hack was fine for temporary use, but far from a mergeable solution due
to the intrusiveness into the timer code.
The code further lacked the ability to detect and report the root cause
instantly and keep the system operational.
Keeping the system operational is important to get hold of the debug
information without special debugging aids like serial consoles and special
knowledge of the bug reporter.
The problems described above are not restricted to timers, but timers tend to
expose it usually in a full system crash. Other objects are less explosive,
but the symptoms caused by such mistakes can be even harder to debug.
Instead of creating specialized debugging code for the timer subsystem a
generic infrastructure is created which allows developers to verify their code
and provides an easy to enable debug facility for users in case of trouble.
The debugobjects core code keeps track of operations on static and dynamic
objects by inserting them into a hashed list and sanity checking them on
object operations and provides additional checks whenever kernel memory is
freed.
The tracked object operations are:
- initializing an object
- adding an object to a subsystem list
- deleting an object from a subsystem list
Each operation is sanity checked before the operation is executed and the
subsystem specific code can provide a fixup function which allows to prevent
the damage of the operation. When the sanity check triggers a warning message
and a stack trace is printed.
The list of operations can be extended if the need arises. For now it's
limited to the requirements of the first user (timers).
The core code enqueues the objects into hash buckets. The hash index is
generated from the address of the object to simplify the lookup for the check
on kfree/vfree. Each bucket has it's own spinlock to avoid contention on a
global lock.
The debug code can be compiled in without being active. The runtime overhead
is minimal and could be optimized by asm alternatives. A kernel command line
option enables the debugging code.
Thanks to Ingo Molnar for review, suggestions and cleanup patches.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Greg KH <greg@kroah.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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