On some architectures, the boot process involves de-registering the boot
console (early boot), initialize drivers and then re-register the console.

This mechanism introduces a window in which no printk can happen on the
console and messages are buffered and then printed once the new console is
available.

If a kernel crashes during this window, all it's left on the boot console
is "console [foo] enabled, bootconsole disabled" making debug of the crash
rather 'interesting'.

By adding "keep_bootcon" option, do not unregister the boot console, that
will allow to printk everything that is happening up to the crash.

The option is clearly meant only for debugging purposes as it introduces
lots of duplicated info printed on console, but will make bug report from
users easier as it doesn't require a kernel build just to figure out where
we crash.

Signed-off-by: Fabio M. Di Nitto <fabbione@fabbione.net>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Greg KH <gregkh@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When a cpu is considered stuck, instead of limping along and just printing
a warning, it is sometimes preferred to just panic, let kdump capture the
vmcore and reboot.  This gets the machine back into a stable state quickly
while saving the info that got it into a stuck state to begin with.

Add a Kconfig option to allow users to set the hardlockup to panic
by default.  Also add in a 'nmi_watchdog=nopanic' to override this.

[akpm@linux-foundation.org: fix strncmp length]
Signed-off-by: Don Zickus <dzickus@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The oops=panic cmdline option is not x86 specific, move it to generic code.
Update documentation.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The new behaviour is enabled using the new module parameter
'nfs4_disable_idmapping'.

Note that if the server rejects an unmapped uid or gid, then
the client will automatically switch back to using the idmapper.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

If firmware allows us to map all of a partition's memory for DMA on a
particular bridge, create a 1:1 mapping of that memory. Add hooks for
dealing with hotplug events. Dynamic DMA windows can use larger than the
default page size, and we use the largest one possible.

Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Add a commandline parameter "threadirqs" which forces all interrupts except
those marked IRQF_NO_THREAD to run threaded. That's mostly a debug option to
allow retrieving better debug data from crashing interrupt handlers. If
"threadirqs" is not enabled on the kernel command line, then there is no
impact in the interrupt hotpath.

Architecture code needs to select CONFIG_IRQ_FORCED_THREADING after
marking the interrupts which cant be threaded IRQF_NO_THREAD. All
interrupts which have IRQF_TIMER set are implict marked
IRQF_NO_THREAD. Also all PER_CPU interrupts are excluded.

Forced threading hard interrupts also forces all soft interrupt
handling into thread context.

When enabled it might slow down things a bit, but for debugging problems in
interrupt code it's a reasonable penalty as it does not immediately
crash and burn the machine when an interrupt handler is buggy.

Some test results on a Core2Duo machine:

Cache cold run of:
 # time git grep irq_desc

      non-threaded       threaded
 real 1m18.741s          1m19.061s
 user 0m1.874s           0m1.757s
 sys  0m5.843s           0m5.427s

 # iperf -c server
non-threaded
[  3]  0.0-10.0 sec  1.09 GBytes   933 Mbits/sec
[  3]  0.0-10.0 sec  1.09 GBytes   934 Mbits/sec
[  3]  0.0-10.0 sec  1.09 GBytes   933 Mbits/sec
threaded
[  3]  0.0-10.0 sec  1.09 GBytes   939 Mbits/sec
[  3]  0.0-10.0 sec  1.09 GBytes   934 Mbits/sec
[  3]  0.0-10.0 sec  1.09 GBytes   937 Mbits/sec

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20110223234956.772668648@linutronix.de>

Update the "log_buf_len" description to use [KMG] syntax for the
buffer size.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The '[KMG]' suffix is commonly described after a number of kernel
parameter values documentation.  Explicitly state its semantics.

Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Complete the crashkernel= kernel parameter documentation.

Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com>
Acked-by: Simon Horman <horms@verge.net.au>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

A B C D E ...

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Enable async PF in a guest if async PF capability is discovered.

Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

i8042 controller present in Dell Vostro V13 errorneously signals spurious
timeouts.

Introduce i8042.notimeout parameter for ignoring i8042-signalled timeouts
and apply this quirk automatically for Dell Vostro V13, based on DMI match.

In addition to that, this machine also needs to be added to nomux blacklist.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

re:
  commit e9d376f0
  Author: Jason Baron <jbaron@redhat.com>
  Date:   Thu Feb 5 11:51:38 2009 -0500

    dynamic debug: combine dprintk and dynamic printk

Above commit obsoleted the kernel parameter, and even removed its
entry in kernel-parameters.txt, but got reinsterted through
0cb55ad2 ("docs: alphabetize entries in kernel-parameters.txt")

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

The error message 'NMI watchdog failed to create perf event...'
does not make it clear that this is a fatal error for the
watchdog.  It also currently prints the error value as a
pointer, rather than extracting the error code with PTR_ERR().
Fix that.

Add a note to the description of the 'nowatchdog' kernel
parameter to associate it with this message.

Reported-by: Cesare Leonardi <celeonar@gmail.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: 599368@bugs.debian.org
Cc: 608138@bugs.debian.org
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: <stable@kernel.org> # .37.x and later
LKML-Reference: <1294009362.3167.126.camel@localhost>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

This reverts commit e7f8567d.

Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

Remove the ACPI video output switching control as it never works.

With the patch applied,
ACPI video driver still catches the video output notification,
but it does nothing but raises the notification to userspace.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

Originally adapted from Huang Ying's patch which moved the
unknown_nmi_panic to the traps.c file.  Because the old nmi
watchdog was deleted before this change happened, the
unknown_nmi_panic sysctl was lost.  This re-adds it.

Also, the nmi_watchdog sysctl was re-implemented and its
documentation updated accordingly.

Patch-inspired-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Don Zickus <dzickus@redhat.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Acked-by: Yinghai Lu <yinghai@kernel.org>
Cc: fweisbec@gmail.com
LKML-Reference: <1291068437-5331-3-git-send-email-dzickus@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

A recurring complaint from CFS users is that parallel kbuild has
a negative impact on desktop interactivity.  This patch
implements an idea from Linus, to automatically create task
groups.  Currently, only per session autogroups are implemented,
but the patch leaves the way open for enhancement.

Implementation: each task's signal struct contains an inherited
pointer to a refcounted autogroup struct containing a task group
pointer, the default for all tasks pointing to the
init_task_group.  When a task calls setsid(), a new task group
is created, the process is moved into the new task group, and a
reference to the preveious task group is dropped.  Child
processes inherit this task group thereafter, and increase it's
refcount.  When the last thread of a process exits, the
process's reference is dropped, such that when the last process
referencing an autogroup exits, the autogroup is destroyed.

At runqueue selection time, IFF a task has no cgroup assignment,
its current autogroup is used.

Autogroup bandwidth is controllable via setting it's nice level
through the proc filesystem:

  cat /proc/<pid>/autogroup

Displays the task's group and the group's nice level.

  echo <nice level> > /proc/<pid>/autogroup

Sets the task group's shares to the weight of nice <level> task.
Setting nice level is rate limited for !admin users due to the
abuse risk of task group locking.

The feature is enabled from boot by default if
CONFIG_SCHED_AUTOGROUP=y is selected, but can be disabled via
the boot option noautogroup, and can also be turned on/off on
the fly via:

  echo [01] > /proc/sys/kernel/sched_autogroup_enabled

... which will automatically move tasks to/from the root task group.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Markus Trippelsdorf <markus@trippelsdorf.de>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Paul Turner <pjt@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
[ Removed the task_group_path() debug code, and fixed !EVENTFD build failure. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <1290281700.28711.9.camel@maggy.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

This introduces a pair of kernel parameters that can be used to disable
the MULTITCE and BULK_REMOVE h-calls.

By default, those hcalls are enabled, active, and good for throughput
and performance.  The ability to disable them will be useful for some of
the PREEMPT_RT related investigation and work occurring on Power.

Signed-off-by: Will Schmidt <will_schmidt@vnet.ibm.com>
cc: Olof Johansson <olof@lixom.net>
cc: Anton Blanchard <anton@samba.org>
cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Swap accounting can be configured by CONFIG_CGROUP_MEM_RES_CTLR_SWAP
configuration option and then it is turned on by default.  There is a boot
option (noswapaccount) which can disable this feature.

This makes it hard for distributors to enable the configuration option as
this feature leads to a bigger memory consumption and this is a no-go for
general purpose distribution kernel.  On the other hand swap accounting
may be very usuful for some workloads.

This patch adds a new configuration option which controls the default
behavior (CGROUP_MEM_RES_CTLR_SWAP_ENABLED).  If the option is selected
then the feature is turned on by default.

It also adds a new boot parameter swapaccount[=1|0] which enhances the
original noswapaccount parameter semantic by means of enable/disable logic
(defaults to 1 if no value is provided to be still consistent with
noswapaccount).

The default behavior is unchanged (if CONFIG_CGROUP_MEM_RES_CTLR_SWAP is
enabled then CONFIG_CGROUP_MEM_RES_CTLR_SWAP_ENABLED is enabled as well)

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Remove anticipatory block I/O scheduler info from Documentation/
since the code has been deleted.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Reported-by: "Robert P. J. Day" <rpjday@crashcourse.ca>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

Allocate space from the top of a region first, then work downward,
if an architecture desires this.

When we allocate space from a resource, we look for gaps between children
of the resource.  Previously, we always looked at gaps from the bottom up.
For example, given this:

    [mem 0xbff00000-0xf7ffffff] PCI Bus 0000:00
      [mem 0xbff00000-0xbfffffff] gap -- available
      [mem 0xc0000000-0xdfffffff] PCI Bus 0000:02
      [mem 0xe0000000-0xf7ffffff] gap -- available

we attempted to allocate from the [mem 0xbff00000-0xbfffffff] gap first,
then the [mem 0xe0000000-0xf7ffffff] gap.

With this patch an architecture can choose to allocate from the top gap
[mem 0xe0000000-0xf7ffffff] first.

We can't do this across the board because iomem_resource.end is initialized
to 0xffffffff_ffffffff on 64-bit architectures, and most machines can't
address the entire 64-bit physical address space.  Therefore, we only
allocate top-down if the arch requests it by clearing
"resource_alloc_from_bottom".

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

Switch default value of the kernel parameter 'topology' from off to on.
Various performance measurements have finally shown that there are no
(known) regressions anywhere.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

Document this parameter into Documentation/kernel-parameters.txt

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

The default state of 'kvm-amd.nested' is enabled now, so fix the documentation

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

no-kvmclock kernel parameter is missing its explanation in
Documentation/kernel-parameters.txt. Add it.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Avi Kivity <avi@redhat.com>

I have some systems which need legacy sysfs due to old tools that are
making assumptions that a directory can never be a symlink to another
directory, and it's a big hazzle to compile separate kernels for them.

This patch turns CONFIG_SYSFS_DEPRECATED into a run time option
that can be switched on/off the kernel command line. This way
the same binary can be used in both cases with just a option
on the command line.

The old CONFIG_SYSFS_DEPRECATED_V2 option is still there to set
the default. I kept the weird name to not break existing
config files.

Also the compat code can be still completely disabled by undefining
CONFIG_SYSFS_DEPRECATED_SWITCH -- just the optimizer takes
care of this now instead of lots of ifdefs. This makes the code
look nicer.

v2: This is an updated version on top of Kay's patch to only
handle the block devices. I tested it on my old systems
and that seems to work.

Cc: axboe@kernel.dk
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

Dynamic debug lacks the ability to enable debug messages at boot time.
One could patch initramfs or service startup scripts to write to
/sys/../dynamic_debug/control, but this sucks.

This patch makes it possible to pass a query in the same format one can
write to /sys/../dynamic_debug/control via boot param.
When dynamic debug gets initialized, this query will automatically be
applied.


Signed-off-by: Thomas Renninger <trenn@suse.de>
Acked-by:  <jbaron@redhat.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

This patch adds IRQ_TIME_ACCOUNTING option on x86 and runtime enables it
when TSC is enabled.

This change just enables fine grained irq time accounting, isn't used yet.
Following patches use it for different purposes.

Signed-off-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1286237003-12406-6-git-send-email-venki@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Compress hibernation image with LZO in order to save on I/O and
therefore time to hibernate/thaw.

[rjw: Added hibernate=nocompress command line option instead of just
 nocompress which would be confusing, fixed a couple of compiler
 warnings, fixed kerneldoc comments, minor cleanups.]

Signed-off-by: Bojan Smojver <bojan@rexursive.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

As a convenience, introduce a kernel command line option to enable
NFSROOT debugging messages.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Add a kernel command-line option so the x86 early memory reservation
size can be adjusted at runtime instead of only at compile time.

Suggested-by: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <tip-d0cd7425@git.kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

After commit 852972ac (ACPI: Disable
ASPM if the platform won't provide _OSC control for PCIe) control of
the PCIe Capability Structure is unconditionally requested by
acpi_pci_root_add(), which in principle may cause problems to
happen in two ways.  First, the BIOS may refuse to give control of
the PCIe Capability Structure if it is not asked for any of the
_OSC features depending on it at the same time.  Second, the BIOS may
assume that control of the _OSC features depending on the PCIe
Capability Structure will be requested in the future and may behave
incorrectly if that doesn't happen.  For this reason, control of
the PCIe Capability Structure should always be requested along with
control of any other _OSC features that may depend on it (ie. PCIe
native PME, PCIe native hot-plug, PCIe AER).

Rework the PCIe port driver so that (1) it checks which native PCIe
port services can be enabled, according to the BIOS, and (2) it
requests control of all these services simultaneously.  In
particular, this causes pcie_portdrv_probe() to fail if the BIOS
refuses to grant control of the PCIe Capability Structure, which
means that no native PCIe port services can be enabled for the PCIe
Root Complex the given port belongs to.  If that happens, ASPM is
disabled to avoid problems with mishandling it by the part of the
PCIe hierarchy for which control of the PCIe Capability Structure
has not been received.

Make it possible to override this behavior using 'pcie_ports=native'
(use the PCIe native services regardless of the BIOS response to the
control request), or 'pcie_ports=compat' (do not use the PCIe native
services at all).

Accordingly, rework the existing PCIe port service drivers so that
they don't request control of the services directly.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

Introduce kernel command line switch pcie_ports= allowing one to
disable all of the native PCIe port services, so that PCIe ports
are treated like PCI-to-PCI bridges.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

With the recent innovations in CPU hardware acceleration technologies
from Intel and AMD, VMware ran a few experiments to compare these
techniques to guest paravirtualization technique on VMware's platform.
These hardware assisted virtualization techniques have outperformed the
performance benefits provided by VMI in most of the workloads. VMware
expects that these hardware features will be ubiquitous in a couple of
years, as a result, VMware has started a phased retirement of this
feature from the hypervisor.

Please note that VMI has always been an optimization and non-VMI kernels
still work fine on VMware's platform.
Latest versions of VMware's product which support VMI are,
Workstation 7.0 and VSphere 4.0 on ESX side, future maintainence
releases for these products will continue supporting VMI.

For more details about VMI retirement take a look at this,
http://blogs.vmware.com/guestosguide/2009/09/vmi-retirement.html



This feature removal was scheduled for 2.6.37 back in September 2009.

Signed-off-by: Alok N Kataria <akataria@vmware.com>
LKML-Reference: <1282600151.19396.22.camel@ank32.eng.vmware.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

It is not immediately clear what this option causes to become
ignored. The actual meaning is that it is not necessary to unplug the
emulated devices to safely use the PV ones, even if the platform does
not support the unplug protocol. (pressumably the user will only add
this option if they have ensured that their domain configuration is
safe).

I think xen_emul_unplug=unnecessary better captures this.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Stefano Stabellini <Stefano.Stabellini@eu.citrix.com>

this allows the user to disable pvhvm and revert to emulated devices
in case of a system misconfiguration (e.g. initramfs with only
emulated drivers in it).

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Stefano Stabellini <Stefano.Stabellini@eu.citrix.com>

kernel-parameters.txt lists 'noreplace-paravirt' parameter as being
limited to X86-32, which is incorrect -- it's actually supported by
x86-32, x86-64 and ia-64.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

Move SCSI parameters from kernel-parameters.txt to their own text file.

This continues a trend of moving non-core parameters out of
kernel-parameters.txt.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

To keep panic_timeout accuracy when running under a hypervisor, the
current implementation only spins on long time (1 second) calls to mdelay.
 That brings a good effect, but the problem is the keyboard LEDs don't
blink at all on that situation.

This patch changes to call to panic_blink_enter() between every mdelay and
keeps blinking in spite of long spin timer mode.

The time to call to mdelay is now 100ms.  Even this change will keep
panic_timeout accuracy enough when running under a hypervisor.

Signed-off-by: TAMUKI Shoichi <tamuki@linet.gr.jp>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: Russell King <linux@arm.linux.org.uk>
Acked-by: Dmitry Torokhov <dtor@mail.ru>
Cc: Anton Blanchard <anton@samba.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>