AMD dual core laptops with C1E do not run the APIC timer correctly
when they go idle. Previously the code assumed this only happened
on C2 or deeper.  But not all of these systems report support C2.

Use a AMD supplied snippet to detect C1E being enabled and then disable
local apic timer use.

This supercedes an earlier workaround using DMI detection of specific systems.

Thanks to Mark Langsdorf for the detection snippet.
Signed-off-by: NAndi Kleen <ak@suse.de>

It turned out that it is almost impossible to trust ACPI, BIOS & Co.
regarding the C states. This was the reason to switch the local apic
timer off in C2 state already. OTOH there are sane and well behaving
systems, which get punished by that decision.

Allow the user to confirm that the local apic timer is trustworthy in C2
state. This keeps the default behaviour on the safe side.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

latest -git triggers an irqtrace/lockdep warning of a leaked
irqs-off condition:

  BUG: at kernel/fork.c:1033 copy_process()

after some debugging it turns out that commit ca1b940c accidentally left
interrupts disabled - which trickled down all the way to the first time
we fork a kernel thread and triggered the warning.

the fix is to re-enable interrupts in the 'else' branch of
setup_boot_APIC_clock()'s pmtimers calibration path.
Reported-by: NMichal Piotrowski <michal.k.k.piotrowski@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Acked-by: NThomas Gleixner <tglx@brown.paperbag.linutronix.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The local APIC timer stops to work in deeper C-States.  This is handled by
the ACPI code and a broadcast mechanism in the clockevents / tick managment
code.

Some systems do not expose the deeper C-States to the kernel, but switch
into deeper C-States behind the kernels back.  This delays the local apic
timer interrupts for ever and makes the systems unusable.

Add a command line option to disable the local apic timer and a dmi
quirk for known broken systems.

Andi sayeth:

  While not wrong by itself i think it is still better to use some heuristic
  -- like "has battery in ACPI" With the DMI table if the problem is more wide
  spread we will just continue extending it.

  But anyways should be ok now for .21 although I'm not really happy with
  it.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NIngo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Grudgingly-acked-by: NAndi Kleen <ak@suse.de>
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When PM-Timer is available for local APIC timer calibration we can skip the
verification of the calibrated time value.  The resulting error is quite
small on a bunch of evaluated platforms and is less harming than the
observed false positives.

We need to keep the verification on systems, which have no PM-Timer to
avoid bogus local APIC timer calibrations in the range of factor 2-10,
which can be observed when swicthing off the PM-timer support in the kernel
configuration.

The wrong calibration values are probably caused by SMM code trying to
emulate a PS/2 keyboard from a (maybe connected or not) USB keyboard.  This
prohibits the accurate delivery of PIT interrupts, which are used to
calibrate the local APIC timer.  Unfortunately we have no way to disable
this BIOS misfeature in the early boot process.

Add also the dropped cpu_relax() back to the wait loops.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NIngo Molnar <mingo@elte.hu>
Acked-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

  Testing NMI watchdog ... CPU#0: NMI appears to be stuck (54->54)!
  CPU#1: NMI appears to be stuck (0->0)!

Keep the PIT/HPET alive when nmi_watchdog = 1 is given on the command
line.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This reverts commit 2ff2d3d7.

Uwe Bugla reports that he cannot mount a floppy drive any more, and Jiri
Slaby bisected it down to this commit.

Benjamin LaHaise also points out that this is a big hot-path, and that
interrupt delivery while idle is very common and should not go through
all these expensive gyrations.

Fix up conflicts in arch/i386/kernel/apic.c and arch/i386/kernel/irq.c
due to other unrelated irq changes.

Cc: Stephane Eranian <eranian@hpl.hp.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Andrew Morton <akpm@osdl.org>
Cc: Uwe Bugla <uwe.bugla@gmx.de>
Cc: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The local apic timer calibration has two problem cases:

1.  The calibration is based on readout of the PIT/HPET timer to detect the
   wrap of the periodic tick.  It happens that a box gets stuck in the
   calibration loop due to a PIT with a broken readout function.

2.  CoreDuo boxen show a sporadic PIT runs too slow defect, which results
   in a wrong lapic calibration.  The PIT goes back to normal operation once
   the lapic timer is switched to periodic mode.

Both are existing and unfixed problems in the current upstream kernel and
prevent certain laptops and other systems from booting Linux.

Rework the code to address both problems:

- Make the calibration interrupt driven.  This removes the wait_timer_tick
  magic hackery from lapic.c and time_hpet.c.  The clockevents framework
  allows easy substitution of the global tick event handler for the
  calibration.  This is more accurate than monitoring jiffies.  At this point
  of the boot process, nothing disturbes the interrupt delivery, so the
  results are very accurate.

- Verify the calibration against the PM timer, when available by using the
  early access function.  When the measured calibration period is outside of
  an one percent window, then the lapic timer calibration is adjusted to the
  pm timer result.

- Verify the calibration by running the lapic timer with the calibration
  handler.  Disable lapic timer in case of deviation.

This also removes the "synchronization" of the local apic timer to the global
tick.  This synchronization never worked, as there is no way to synchronize
PIT(HPET) and local APIC timer.  The synchronization by waiting for the tick
just alignes the local APIC timer for the first events, but later the events
drift away due to the different clocks.  Removing the "sync" is just
randomizing the asynchronous behaviour at setup time.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Cc: Zachary Amsden <zach@vmware.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Rohit Seth <rohitseth@google.com>
Cc: Andi Kleen <ak@suse.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add clockevent drivers for i386: lapic (local) and PIT/HPET (global).  Update
the timer IRQ to call into the PIT/HPET driver's event handler and the
lapic-timer IRQ to call into the lapic clockevent driver.  The assignement of
timer functionality is delegated to the core framework code and replaces the
compile and runtime evalution in do_timer_interrupt_hook()

Use the clockevents broadcast support and implement the lapic_broadcast
function for ACPI.

No changes to existing functionality.

[ kdump fix from Vivek Goyal <vgoyal@in.ibm.com> ]
[ fixes based on review feedback from Arjan van de Ven <arjan@infradead.org> ]
Cleanups-from: Adrian Bunk <bunk@stusta.de>
Build-fixes-from: Andrew Morton <akpm@osdl.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The apic code is quite unstructured and missing a lot of comments.

- Restructure the code into helper functions, timer, setup/shutdown,
  interrupt and power management blocks.
- Fixup comments.
- Namespace fixups
- Inline helpers for version and is_integrated
- Combine the ack_bad_irq functions

No functional changes.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Cc: Zachary Amsden <zach@vmware.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Rohit Seth <rohitseth@google.com>
Cc: Andi Kleen <ak@suse.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add a notifier mechanism to the low level idle loop.  You can register a
callback function which gets invoked on entry and exit from the low level idle
loop.  The low level idle loop is defined as the polling loop, low-power call,
or the mwait instruction.  Interrupts processed by the idle thread are not
considered part of the low level loop.

The notifier can be used to measure precisely how much is spent in useless
execution (or low power mode).  The perfmon subsystem uses it to turn on/off
monitoring.
Signed-off-by: Nstephane eranian <eranian@hpl.hp.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NAndi Kleen <ak@suse.de>

VMI timer code.  It works by taking over the local APIC clock when APIC is
configured, which requires a couple hooks into the APIC code.  The backend
timer code could be commonized into the timer infrastructure, but there are
some pieces missing (stolen time, in particular), and the exact semantics of
when to do accounting for NO_IDLE need to be shared between different
hypervisors as well.  So for now, VMI timer is a separate module.

[Adrian Bunk: cleanups]

Subject: VMI timer patches
Signed-off-by: NZachary Amsden <zach@vmware.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>

Read/Write APIC_LVTPC and APIC_LVTTHMR only,
if get_maxlvt() returns certain values.
This is done like everywhere else in i386/kernel/apic.c,
so I guess its correct.
Suspends/Resumes to disk fine and eleminates an smp_error_interrupt()
here on a K8.

AK: ported to x86-64 too
Signed-off-by: NKarsten Wiese <fzu@wemgehoertderstaat.de>
Signed-off-by: NAndi Kleen <ak@suse.de>

Cc: David Howells <dhowells@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Maintain a per-CPU global "struct pt_regs *" variable which can be used instead
of passing regs around manually through all ~1800 interrupt handlers in the
Linux kernel.

The regs pointer is used in few places, but it potentially costs both stack
space and code to pass it around.  On the FRV arch, removing the regs parameter
from all the genirq function results in a 20% speed up of the IRQ exit path
(ie: from leaving timer_interrupt() to leaving do_IRQ()).

Where appropriate, an arch may override the generic storage facility and do
something different with the variable.  On FRV, for instance, the address is
maintained in GR28 at all times inside the kernel as part of general exception
handling.

Having looked over the code, it appears that the parameter may be handed down
through up to twenty or so layers of functions.  Consider a USB character
device attached to a USB hub, attached to a USB controller that posts its
interrupts through a cascaded auxiliary interrupt controller.  A character
device driver may want to pass regs to the sysrq handler through the input
layer which adds another few layers of parameter passing.

I've build this code with allyesconfig for x86_64 and i386.  I've runtested the
main part of the code on FRV and i386, though I can't test most of the drivers.
I've also done partial conversion for powerpc and MIPS - these at least compile
with minimal configurations.

This will affect all archs.  Mostly the changes should be relatively easy.
Take do_IRQ(), store the regs pointer at the beginning, saving the old one:

	struct pt_regs *old_regs = set_irq_regs(regs);

And put the old one back at the end:

	set_irq_regs(old_regs);

Don't pass regs through to generic_handle_irq() or __do_IRQ().

In timer_interrupt(), this sort of change will be necessary:

	-	update_process_times(user_mode(regs));
	-	profile_tick(CPU_PROFILING, regs);
	+	update_process_times(user_mode(get_irq_regs()));
	+	profile_tick(CPU_PROFILING);

I'd like to move update_process_times()'s use of get_irq_regs() into itself,
except that i386, alone of the archs, uses something other than user_mode().

Some notes on the interrupt handling in the drivers:

 (*) input_dev() is now gone entirely.  The regs pointer is no longer stored in
     the input_dev struct.

 (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking.  It does
     something different depending on whether it's been supplied with a regs
     pointer or not.

 (*) Various IRQ handler function pointers have been moved to type
     irq_handler_t.
Signed-Off-By: NDavid Howells <dhowells@redhat.com>
(cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)

enable_local_apic can now become static.

Cc: len.brown@intel.com
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Signed-off-by: NAndi Kleen <ak@suse.de>

This patch replaces the open-coded early commandline parsing
throughout the i386 boot code with the generic mechanism (already used
by ppc, powerpc, ia64 and s390).  The code was inconsistent with
whether it deletes the option from the cmdline or not, meaning some of
these will get passed through the environment into init.

This transformation is mainly mechanical, but there are some notable
parts:

1) Grammar: s/linux never set's it up/linux never sets it up/

2) Remove hacked-in earlyprintk= option scanning.  When someone
   actually implements CONFIG_EARLY_PRINTK, then they can use
   early_param().
[AK: actually it is implemented, but I'm adding the early_param it in the next
x86-64 patch]

3) Move declaration of generic_apic_probe() from setup.c into asm/apic.h

4) Various parameters now moved into their appropriate files (thanks Andi).

5) All parse functions which examine arg need to check for NULL,
   except one where it has subtle humor value.

AK: readded acpi_sci handling which was completely dropped
AK: moved some more variables into acpi/boot.c

Cc: len.brown@intel.com
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndi Kleen <ak@suse.de>

This patch includes the changes to make the nmi watchdog on i386 SMP aware.
A bunch of code was moved around to make it simpler to read.  In addition,
it is now possible to determine if a particular NMI was the result of the
watchdog or not.  This feature allows the kernel to filter out unknown NMIs
easier.
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Signed-off-by: NAndi Kleen <ak@suse.de>

Signed-off-by: NJörn Engel <joern@wohnheim.fh-wedel.de>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>

Appended patch fixes the "APIC error on CPUX: 00(40)" observed during bootup.

From SDM Vol-3A "Valid Interrupt Vectors" section:
	"When an illegal vector value (0-15) is written to an LVT entry
	and the delivery mode is Fixed, the APIC may signal an illegal
	vector error, with out regard to whether the mask bit is set
	or whether an interrupt is actually seen on input."
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Misc header cleanup for nmi watchdog.
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Signed-off-by: NAndreas Mohr <andi@lisas.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

o Kdump second kernel boot fails after a system crash if second kernel
  is UP and acpi=off and if crash occurred on a non-boot cpu.

o Issue here is that MP tables report boot cpu lapic id as 0 but second
  kernel is booting on a different processor and MP table data is stale
  in this context. Hence apic_id_registered() check fails in setup_local_APIC()
  when called from APIC_init_uniprocessor().

o Problem is not seen if ACPI is enabled as in that case
  boot_cpu_physical_apicid is read from the LAPIC.

o Problem is not seen with SMP kernels as well because in this case also
  boot_cpu_physical_apicid is read from LAPIC. (smp_boot_cpus()).

o The problem is fixed by reading boot_cpu_physical_apicid from LAPIC
  if it is a UP kernel and CRASH_DUMP is enabled.
Signed-off-by: NVivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The apic= option can be used to set the APIC driver too.  When that is done
this code would always produce bogus warnings.
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

AMD systems have a modern APIC that supports 8 bit IDs, but
don't have a XAPIC version number.  Add a new "modern_apic"
subfunction that handles this correctly and use it (nearly)
everywhere where XAPIC is tested for.

I removed one wart: the code specified that external APICs
would use an 8bit APIC ID. But I checked a real 82093 data sheet
and it says clearly that they only use 4bit. So I removed
this special case since it would a bit awkward to implement now.

I removed the valid APIC tests in mptable parsing completely. On any modern
system they only check against the full field width (8bit) anyways
and are no-ops. This also fixes them doing the wrong thing
on >8 core Opterons.

This makes i386 boot again on 16 core Opterons.

Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The boot cmdline is parsed in parse_early_param() and
parse_args(,unknown_bootoption).

And __setup() is used in obsolete_checksetup().

	start_kernel()
		-> parse_args()
			-> unknown_bootoption()
				-> obsolete_checksetup()

If __setup()'s callback (->setup_func()) returns 1 in
obsolete_checksetup(), obsolete_checksetup() thinks a parameter was
handled.

If ->setup_func() returns 0, obsolete_checksetup() tries other
->setup_func().  If all ->setup_func() that matched a parameter returns 0,
a parameter is seted to argv_init[].

Then, when runing /sbin/init or init=app, argv_init[] is passed to the app.
If the app doesn't ignore those arguments, it will warning and exit.

This patch fixes a wrong usage of it, however fixes obvious one only.
Signed-off-by: NOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Porting the patch I posted for x86_64 to i386.

http://marc.theaimsgroup.com/?l=linux-kernel&m=114178139610707&w=2

o While using kdump, after a system crash when second kernel boots, timer
  vector gets (0x31) locked and CPU does not see timer interrupts
  travelling from IOAPIC to APIC.  Currently it does not lead to boot
  failure in second kernel as timer interrupts continues to come as ExtInt
  through LAPIC directly, but fixing it is good in case some boards do not
  support the other mode.

o After a system crash, it is not safe to service interrupts any more,
  hence interrupts are disabled.  This leads to pending interrupts at
  LAPIC.  LAPIC sends these interrupts to the CPU during early boot of
  second kernel.  Other pending interrupts are discarded saying unexpected
  trap but timer interrupt is serviced and CPU does not issue an LAPIC EOI
  because it think this interrupt came from i8259 and sends ack to 8259.
  This leads to vector 0x31 locking as LAPIC does not clear respective ISR
  and keeps on waiting for EOI.

o This patch issues extra EOI for the pending interrupts who have ISR set.

o Though today only timer seems to be the special case because in early
  boot it thinks interrupts are coming from i8259 and uses
  mask_and_ack_8259A() as ack handler and does not issue LAPIC EOI.  But
  probably doing it in generic manner for all vectors makes sense.
Signed-off-by: NVivek Goyal <vgoyal@in.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

arch/i386/kernel/apic.c:840: warning: implicit declaration of function `GET_APIC_ID'
Signed-off-by: NJesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

lapic_shutdown() re-enables interrupts which is un-desirable for panic
case, so use local_irq_save() and local_irq_restore() to keep the irqs
disabled for kexec on panic case, and close a possible race window while
kdump shutdown as shown in this stack trace

   -- BUG: spinlock lockup on CPU#1, bash/4396, c52781a0
   [<c01c1870>] _raw_spin_lock+0xb7/0xd2
   [<c029e148>] _spin_lock+0x6/0x8
   [<c011b33f>] scheduler_tick+0xe7/0x328
   [<c0128a7c>] update_process_times+0x51/0x5d
   [<c0114592>] smp_apic_timer_interrupt+0x4f/0x58
   [<c01141ff>] lapic_shutdown+0x76/0x7e
   [<c0104d7c>] apic_timer_interrupt+0x1c/0x30
   [<c01141ff>] lapic_shutdown+0x76/0x7e
   [<c0116659>] machine_crash_shutdown+0x83/0xaa
   [<c013cc36>] crash_kexec+0xc1/0xe3
   [<c029e148>] _spin_lock+0x6/0x8
   [<c013cc22>] crash_kexec+0xad/0xe3
   [<c0215280>] __handle_sysrq+0x84/0xfd
   [<c018d937>] write_sysrq_trigger+0x2c/0x35
   [<c015e47b>] vfs_write+0xa2/0x13b
   [<c015ea73>] sys_write+0x3b/0x64
   [<c0103c69>] syscall_call+0x7/0xb
Signed-off-by: NManeesh Soni <maneesh@in.ibm.com>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Fix wrong '!' in bad apic fix

I forgot to remove the ! when moving the code from x86-64 to i386 x86-64
tested !disable_apic, but of course for cpu_has_apic it shouldn't be
negated.

Credit goes to Jan Beulich for spotting it with eagle eyes.

Cc: Jan Beulich <jbeulich@novell.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

It's bad juju to touch the APIC when it hasn't been enabled.
I also moved ack_bad_irq for x86-64 out of line following i386.
Signed-off-by: NAndi Kleen <ak@suse.de>
Acked-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Whenever we see that a CPU is capable of C3 (during ACPI cstate init), we
disable local APIC timer and switch to using a broadcast from external timer
interrupt (IRQ 0). This is needed because Intel CPUs stop the local
APIC timer in C3.  This is currently only enabled for Intel CPUs.

Patch below adds the code for i386 and also the ACPI hunk.
Signed-off-by: NVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Remove the finer control of local APIC timer. We cannot provide a sub-jiffy
control like this when we use broadcast from external timer in place of
local APIC. Instead of removing this only on systems that may end up using
broadcast from external timer (due to C3), I am going the
"I'm feeling lucky" way to remove this fully. Basically, I am not sure about
usefulness of this code today. Few other architectures also don't seem to
support this today.

If you are using profiling and fine grained control and don't like this going
away in normal case, yell at me right now.
Signed-off-by: NVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Missing newline in printk.
Signed-off-by: NDave Jones <davej@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Excerpt from bugzilla entry

http://bugzilla.kernel.org/show_bug.cgi?id=5518

"i386 version of Reboot-through-BIOS is unsafe: it forgets to mask APIC LVT
interrupts before jumping to a BIOS entry point.  As a result, BIOS ends up
bombarded with interrupts early on boot.  The BIOS does not expect it since
following a "normal" hardware cpu reset, all APIC LVT registers have the
Mask bit (16) set and can't generate interrupts.

For example, the version of Phoenix BIOS used by VMware enables interrupts
for the first time before masking/clearing APIC LVT.  The APIC Timer LVT
register is still set up for a timer interrupt delivery with a high vector
from the previous Linux incarnation (0xef in our case).  The BIOS has not
fully initialized its IDT at this point and the real mode gate for 0xef
remains all zeros.  Vector 0xef dispatches BIOS to address 0:0, BIOS takes
a #GP and eventually hangs.

machine_shutdown() does attempt to shut down APIC before jumping to BIOS,
but it is ineffective"
Signed-off-by: NZwane Mwaikambo <zwane@arm.linux.org.uk>
Cc: "Seth, Rohit" <rohit.seth@intel.com>
Cc: Zachary Amsden <zach@vmware.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Commit f2b36db6 causes a bootup hang on
at least one machine.  Revert for now until we understand why.  The old
code may be ugly, but it works.
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

o Removes the unnecessary call to local_irq_disable().

o Kdump was failing while second kernel was coming up. Check for presence
  of boot cpu apic id was failing in (apic_id_registered), hence hitting
  BUG().

o This should not have failed because before calling setup_local_APIC(), it is
  ensured that even if BIOS has not reported boot cpu, then hard set the
  prence of it. Problem happens because of usage of hard_smp_processor_id()
  which is hardcoded to zero in case of non SMP kernel. In kdump case second
  kernel can boot on a cpu whose boot cpu id is not zero.

o Using boot_cpu_physical_apicid instead to hard set the presence of boot cpu.
Signed-off-by: NVivek Goyal <vgoyal@in.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

All kinds of ugliness exists because we don't initialize
the apics during init_IRQs.
- We calibrate jiffies in non apic mode even when we are using apics.
- We have to have special code to initialize the apics when non-smp.
- The legacy i8259 must exist and be setup correctly, even
  when we won't use it past initialization.
- The kexec on panic code must restore the state of the io_apics.
- init/main.c needs a special case for !smp smp_init on x86

In addition to pure code movement I needed a couple
of non-obvious changes:
- Move setup_boot_APIC_clock into APIC_late_time_init for
  simplicity.
- Use cpu_khz to generate a better approximation of loops_per_jiffies
  so I can verify the timer interrupt is working.
- Call setup_apic_nmi_watchdog again after cpu_khz is initialized on
  the boot cpu.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

	Most of these guys are simply not needed (pulled by other stuff
via asm-i386/hardirq.h).  One that is not entirely useless is hilarious -
arch/i386/oprofile/nmi_timer_int.c includes linux/irq.h... as a way to
get linux/errno.h
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>