- Copy stable/10@296371 to releng/10.3 in preparation for 10.3-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.3.
- Update default pkg(8) configuration to use the quarterly branch.

Approved by: re (implicit)

Merge r264984

Retire smp_active. It was racey and caused demonstrated problems with
the cpufreq code. Replace its use with smp_started. There's at least
one userland tool that still looks at the kern.smp.active sysctl, so
preserve it but point it to smp_started as well.

Obtained from: Netflix, Inc.

MFC 261517,261520:
Convert the license on files where I am the sole copyright holder to
2 clause BSD licenses.

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Fix ia64 and mips kernel builds due to XENHVM=>GENERIC integration in
revision 255744.

sys/kern/subr_smp.c:
IPI_SUSPEND is only available on amd64 and i386. Protect
new uses of this constant with #ifdefs to avoid impacting
other platforms.

Approved by: re (blanket Xen)

Merge Xen PVHVM support into the GENERIC kernel config for both
amd64 and i386.

Submitted by: Roger Pau Monné
Sponsored by: Citrix Systems R&D
Reviewed by: gibbs
Approved by: re (blanket Xen)
MFC after: 2 weeks

sys/amd64/amd64/mp_machdep.c:
sys/amd64/include/cpu.h:
sys/i386/i386/mp_machdep.c:
sys/i386/include/cpu.h:
- Introduce two new CPU hooks for initialization and resume
purposes. This allows us to get rid of the XENHVM ifdefs in
mp_machdep, and also sets some hooks into common code that can be
used by other hypervisor implementations.

sys/amd64/conf/XENHVM:
sys/i386/conf/XENHVM:
- Remove these configs now that GENERIC has builtin support for Xen
HVM.

sys/kern/subr_smp.c:
- Make sure there are no pending IPIs when suspending a system.

sys/x86/xen/hvm.c:
- Add cpu init and resume vectors that are called from mp_machdep
using the new hooks.
- Only clear the vcpu_info mapping data on resume. It is already
clear for the BSP on a cold boot and is set correctly as APs
are started.
- Gate xen_hvm_init_cpu only to systems running under Xen.

sys/x86/xen/xen_intr.c:
- Gate the setup of event channels only to systems running under Xen.

Add support for suspend/resume/migration operations when running as a
Xen PVHVM guest.

Submitted by: Roger Pau Monné
Sponsored by: Citrix Systems R&D
Reviewed by: gibbs
Approved by: re (blanket Xen)
MFC after: 2 weeks

sys/amd64/amd64/mp_machdep.c:
sys/i386/i386/mp_machdep.c:
- Make sure that are no MMU related IPIs pending on migration.
- Reset pending IPI_BITMAP on resume.
- Init vcpu_info on resume.

sys/amd64/include/intr_machdep.h:
sys/i386/include/intr_machdep.h:
sys/x86/acpica/acpi_wakeup.c:
sys/x86/x86/intr_machdep.c:
sys/x86/isa/atpic.c:
sys/x86/x86/io_apic.c:
sys/x86/x86/local_apic.c:
- Add a "suspend_cancelled" parameter to pic_resume(). For the
Xen PIC, restoration of interrupt services differs between
the aborted suspend and normal resume cases, so we must provide
this information.

sys/dev/acpica/acpi_timer.c:
sys/dev/xen/timer/timer.c:
sys/timetc.h:
- Don't swap out "suspend safe" timers across a suspend/resume
cycle. This includes the Xen PV and ACPI timers.

sys/dev/xen/control/control.c:
- Perform proper suspend/resume process for PVHVM:
- Suspend all APs before going into suspension, this allows us
to reset the vcpu_info on resume for each AP.
- Reset shared info page and callback on resume.

sys/dev/xen/timer/timer.c:
- Implement suspend/resume support for the PV timer. Since FreeBSD
doesn't perform a per-cpu resume of the timer, we need to call
smp_rendezvous in order to correctly resume the timer on each CPU.

sys/dev/xen/xenpci/xenpci.c:
- Don't reset the PCI interrupt on each suspend/resume.

sys/kern/subr_smp.c:
- When suspending a PVHVM domain make sure there are no MMU IPIs
in-flight, or we will get a lockup on resume due to the fact that
pending event channels are not carried over on migration.
- Implement a generic version of restart_cpus that can be used by
suspended and stopped cpus.

sys/x86/xen/hvm.c:
- Implement resume support for the hypercall page and shared info.
- Clear vcpu_info so it can be reset by APs when resuming from
suspension.

sys/dev/xen/xenpci/xenpci.c:
sys/x86/xen/hvm.c:
sys/x86/xen/xen_intr.c:
- Support UP kernel configurations.

sys/x86/xen/xen_intr.c:
- Properly rebind per-cpus VIRQs and IPIs on resume.

- Correctly handle EWOULDBLOCK in quiesce_cpus

Discussed with: mav

- Implement run-time expansion of the KTR buffer via sysctl.
- Implement a function to ensure that all preempted threads have switched
back out at least once. Use this to make sure there are no stale
references to the old ktr_buf or the lock profiling buffers before
updating them.

Reviewed by: marius (sparc64 parts), attilio (earlier patch)
Sponsored by: EMC / Isilon Storage Division

Another fixe for r236772.

- Adjust correct cpuset (stopped_cpus/suspended_cpus) for
cpu_spinwait() in generic_stop_cpus().

Add x86/acpica/acpi_wakeup.c for amd64 and i386. Difference of
suspend/resume procedures are minimized among them.

common:
- Add global cpuset suspended_cpus to indicate APs are suspended/resumed.
- Remove acpi_waketag and acpi_wakemap from acpivar.h (no longer used).
- Add some variables in acpi_wakecode.S in order to minimize the difference
among amd64 and i386.
- Disable load_cr3() because now CR3 is restored in resumectx().

amd64:
- Add suspend/resume related members (such as MSR) in PCB.
- Modify savectx() for above new PCB members.
- Merge acpi_switch.S into cpu_switch.S as resumectx().

i386:
- Merge(and remove) suspendctx() into savectx() in order to match with
amd64 code.

Reviewed by: attilio@, acpi@

Add SMP/i386 suspend/resume support.
Most part is merged from amd64.

- i386/acpica/acpi_wakecode.S
Replaced with amd64 code (from realmode to paging enabling code).

- i386/acpica/acpi_wakeup.c
Replaced with amd64 code (except for wakeup_pagetables stuff).

- i386/include/pcb.h
- i386/i386/genassym.c
Added PCB new members (CR0, CR2, CR4, DS, ED, FS, SS, GDT, IDT, LDT
and TR) needed for suspend/resume, not for context switch.

- i386/i386/swtch.s
Added suspendctx() and resumectx().
Note that savectx() was not changed and used for suspending (while
amd64 code uses it).
BSP and AP execute the same sequence, suspendctx(), acpi_wakecode()
and resumectx() for suspend/resume (in case of UP system also).

- i386/i386/apic_vector.s
Added cpususpend().

- i386/i386/mp_machdep.c
- i386/include/smp.h
Added cpususpend_handler().

- i386/include/apicvar.h
- kern/subr_smp.c
- sys/smp.h
Added IPI_SUSPEND and suspend_cpus().

- i386/i386/initcpu.c
- i386/i386/machdep.c
- i386/include/md_var.h
- pc98/pc98/machdep.c
Moved initializecpu() declarations to md_var.h.

MFC after: 3 days

Mark all SYSCTL_NODEs static that have no corresponding SYSCTL_DECLs.

The SYSCTL_NODE macro defines a list that stores all child-elements of
that node. If there's no SYSCTL_DECL macro anywhere else, there's no
reason why it shouldn't be static.

Disable interrupt and preemption for smp_rendezvous() also in the
UP/!SMP case.
The callbacks may be relying on this feature and having 2 different
ways to deal with them is not correct.

Reported by: rstone
Reviewed by: jhb
MFC after: 2 weeks

smp_rendezvous: master cpu should wait until all slaves are fully done

This is a followup to r222032 and a reimplementation of it.
While that revision fixed the race for the smp_rv_waiters[2] exit
sentinel, it still left a possibility for a target CPU to access
stale or wrong smp_rv_func_arg in smp_rv_teardown_func.
To fix this race the slave CPUs signal when they are really fully
done with the rendezvous and the master CPU waits until all slaves
are done.

Diagnosed by: kib
Reviewed by: jhb, mlaier, neel
Approved by: re (kib)
MFC after: 2 weeks

Define two new sysctl node flags: CTLFLAG_CAPRD and CTLFLAG_CAPRW, which
may be jointly referenced via the mask CTLFLAG_CAPRW. Sysctls with these
flags are available in Capsicum's capability mode; other sysctl nodes are
not.

Flag several useful sysctls as available in capability mode, such as memory
layout sysctls required by the run-time linker and malloc(3). Also expose
access to randomness and available kernel features.

A few sysctls are enabled to support name->MIB conversion; these may leak
information to capability mode by virtue of providing resolution on names
not flagged for access in capability mode. This is, generally, not a huge
problem, but might be something to resolve in the future. Flag these cases
with XXX comments.

Submitted by: jonathan
Sponsored by: Google, Inc.

With retirement of cpumask_t and usage of cpuset_t for representing a
mask of CPUs, pc_other_cpus and pc_cpumask become highly inefficient.

Remove them and replace their usage with custom pc_cpuid magic (as,
atm, pc_cpumask can be easilly represented by (1 << pc_cpuid) and
pc_other_cpus by (all_cpus & ~(1 << pc_cpuid))).

This change is not targeted for MFC because of struct pcpu members
removal and dependency by cpumask_t retirement.

MD review by: marcel, marius, alc
Tested by: pluknet
MD testing by: marcel, marius, gonzo, andreast

generic_stop_cpus: pull timeout logic from under DIAGNOSTIC

... and also increase the timeout.
It's better to try to proceed somehow despite stuck CPUs than to hang
indefinitely. Especially so during shutdown and when entering kdb or panic.

Timeout value is still an aribitrary value.
Timeout diagnostic is just a printf; the work on something more
debuggable is planned by attilio. Need to be careful here as
stop_cpus_hard is called very early while enetering kdb and soon(-ish)
it may become called very early when entering panic.

Reviewed by: attilio
MFC after: 2 months

etire the cpumask_t type and replace it with cpuset_t usage.

This is intended to fix the bug where cpu mask objects are
capped to 32. MAXCPU, then, can now arbitrarely bumped to whatever
value. Anyway, as long as several structures in the kernel are
statically allocated and sized as MAXCPU, it is suggested to keep it
as low as possible for the time being.

Technical notes on this commit itself:
- More functions to handle with cpuset_t objects are introduced.
The most notable are cpusetobj_ffs() (which calculates a ffs(3)
for a cpuset_t object), cpusetobj_strprint() (which prepares a string
representing a cpuset_t object) and cpusetobj_strscan() (which
creates a valid cpuset_t starting from a string representation).
- pc_cpumask and pc_other_cpus are target to be removed soon.
With the moving from cpumask_t to cpuset_t they are now inefficient
and not really useful. Anyway, for the time being, please note that
access to pcpu datas is protected by sched_pin() in order to avoid
migrating the CPU while reading more than one (possible) word
- Please note that size of cpuset_t objects may differ between kernel
and userland. While this is not directly related to the patch itself,
it is good to understand that concept and possibly use the patch
as a reference on how to deal with cpuset_t objects in userland, when
accessing kernland members.
- KTR_CPUMASK is changed and now is represented through a string, to be
set as the example reported in NOTES.

Please additively note that no MAXCPU is bumped in this patch, but
private testing has been done until to MAXCPU=128 on a real 8x8x2(htt)
machine (amd64).

Please note that the FreeBSD version is not yet bumped because of
the upcoming pcpu changes. However, note that this patch is not
targeted for MFC.

People to thank for the time spent on this patch:
- sbruno, pluknet and Nicholas Esborn (nick AT desert DOT net) tested
several revision of the patches and really helped in improving
stability of this work.
- marius fixed several bugs in the sparc64 implementation and reviewed
patches related to ktr.
- jeff and jhb discussed the basic approach followed.
- kib and marcel made targeted review on some specific part of the
patch.
- marius, art, nwhitehorn and andreast reviewed MD specific part of
the patch.
- marius, andreast, gonzo, nwhitehorn and jceel tested MD specific
implementations of the patch.
- Other people have made contributions on other patches that have been
already committed and have been listed separately.

Companies that should be mentioned for having participated at several
degrees:
- Yahoo! for having offered the machines used for testing on big
count of CPUs.
- The FreeBSD Foundation for having sponsored my devsummit attendance,
which has been instrumental.
- Sandvine for having offered offices and infrastructure during
development.

(I really hope I didn't forget anyone, if it happened I apologize in
advance).

Silly spelling typos.

Submitted by: "b. f."

Fix an issue with critical sections and SMP rendezvous handlers.
Specifically, a critical_exit() call that drops the nesting level to zero
has a brief window where the pending preemption flag is set and the
nesting level is set to zero. This is done purposefully to avoid races
where a preemption scheduled by an interrupt could be lost otherwise (see
revision 144777). However, this does mean that if an interrupt fires
during this window and enters and exits a critical section, it may preempt
from the interrupt context. This is generally fine as the interrupt code
is careful to arrange critical sections so that they are not exited until
it is safe to preempt (e.g. interrupts EOI'd and masked if necessary).

However, the SMP rendezvous IPI handler does not quite follow this rule,
and in general a rendezvous can never be preempted. Rendezvous handlers
are also not permitted to schedule threads to execute, so they will not
typically trigger preemptions. SMP rendezvous handlers may use
spinlocks (carefully) such as the rm_cleanIPI() handler used in rmlocks,
but using a spinlock also enters and exits a critical section. If the
interrupted top-half code is in the brief window of critical_exit() where
the nesting level is zero but a preemption is pending, then releasing the
spinlock can trigger a preemption. Because we know that SMP rendezvous
handlers can never schedule a thread, we know that a critical_exit() in
an SMP rendezvous handler will only preempt in this edge case. We also
know that the top-half thread will happily handle the deferred preemption
once the SMP rendezvous has completed, so the preemption will not be lost.

This makes it safe to employ a workaround where we use a nested critical
section in the SMP rendezvous code itself around rendezvous action
routines to prevent any preemptions during an SMP rendezvous. The
workaround intentionally avoids checking for a deferred preemption
when leaving the critical section on the assumption that if there is a
pending preemption it will be handled by the interrupted top-half code.

Submitted by: mlaier (variation specific to rm_cleanIPI())
Obtained from: Isilon
MFC after: 1 week

Fix a race in the SMP rendezvous code. Specifically, the write by the
last CPU to to finish the rendezvous action may become visible to
different CPUs at different times. As a result, the CPU that initiated
the rendezvous may exit the rendezvous and drop the lock allowing another
rendezvous to be initiated on the same CPU or a different CPU. In that
case the exit sentinel may be cleared before all CPUs have noticed causing
those CPUs to hang forever.

Workaround this by using a generation count to notice when this race
occurs and to exit the rendezvous in that case.

The problem was independently diagnosted by mlaier@ and avg@ as well.

Submitted by: neel
Reviewed by: avg, mlaier
Obtained from: NetApp
MFC after: 1 week

Merge r221278 from largeSMP project:
idle_cpus_mask is just used in sched_4bsd, thus make it private for it.

Tested by: several

With smp_topo_none, set cg_mask to all_cpus rather than setting the mp_ncpus
low bits.

Submitted by: Bhanu Prakash
Reviewed by: jeffr

sysctl(9) cleanup checkpoint: amd64 GENERIC builds cleanly.

Commit the kernel changes.

generic_stop_cpus: prevent parallel execution

This is based on the same approach as used in panic().
In theory parallel execution of generic_stop_cpus() could lead to two CPUs
stopping each other and everyone else, and thus a total system halt.
Also, in theory, we should have some smarter locking here, because two
(or more CPUs) could be stopping unrelated sets of CPUs.
But in practice, it seems, this function is only used to stop
"all other" CPUs.

Additionally, I took this opportunity to make amd64-specific suspend_cpus()
function use generic_stop_cpus() instead of rolling out essentially
duplicate code.

This code is based on code by Sandvine Incorporated.

Suggested by: mdf
Reviewed by: jhb, jkim (earlier version)
MFC after: 2 weeks

The r208165 fixed a bug related to unsigned integer overflowing for the
number of CPUs detection.
However, that was not mention at all, the problem was not reported, the
patch has not been MFCed and the fix is mostly improper.

Fix the original overflow (caused when 32 CPUs must be detected) by
just using a different mathematical computation (it also makes more
explicit the size of operands involved, which is good in the moment
waiting for a more complete support for a large number of CPUs).

PR: kern/148698
Submitted by: Joe Landers <jlanders at vmware dot com>
Tested by: gianni
MFC after: 10 days

Add a new ipi_cpu() function to the MI IPI API that can be used to send an
IPI to a specific CPU by its cpuid. Replace calls to ipi_selected() that
constructed a mask for a single CPU with calls to ipi_cpu() instead. This
will matter more in the future when we transition from cpumask_t to
cpuset_t for CPU masks in which case building a CPU mask is more expensive.

Submitted by: peter, sbruno
Reviewed by: rookie
Obtained from: Yahoo! (x86)
MFC after: 1 month

Update several places that iterate over CPUs to use CPU_FOREACH().

This pushes all of JC's patches that I have in place. I
am now able to run 32 cores ok.. but I still will hang
on buildworld with a NFS problem. I suspect I am missing
a patch for the netlogic rge driver.

JC check and see if I am missing anything except your
core-mask changes

Obtained from: JC

Fix a hang introduced in r206878 for kernel compiled with SMP support but
being not actual SMP and similar situations by always initializing the
smp ipi mutex.

Reported by: marius
MFC after: 3 days
X-MFC: r206878

Remove forward_roundrobin(), it is unused for quite some time.

Reviewed by: jhb
MFC after: 1 week

* Completely Remove the option STOP_NMI from the kernel. This option
has proven to have a good effect when entering KDB by using a NMI,
but it completely violates all the good rules about interrupts
disabled while holding a spinlock in other occasions. This can be the
cause of deadlocks on events where a normal IPI_STOP is expected.
* Adds an new IPI called IPI_STOP_HARD on all the supported architectures.
This IPI is responsible for sending a stop message among CPUs using a
privileged channel when disponible. In other cases it just does match a
normal IPI_STOP.
Right now the IPI_STOP_HARD functionality uses a NMI on ia32 and amd64
architectures, while on the other has a normal IPI_STOP effect. It is
responsibility of maintainers to eventually implement an hard stop
when necessary and possible.
* Use the new IPI facility in order to implement a new userend SMP kernel
function called stop_cpus_hard(). That is specular to stop_cpu() but
it does use the privileged channel for the stopping facility.
* Let KDB use the newly introduced function stop_cpus_hard() and leave
stop_cpus() for all the other cases
* Disable interrupts on CPU0 when starting the process of APs suspension.
* Style cleanup and comments adding

This patch should fix the reboot/shutdown deadlocks many users are
constantly reporting on mailing lists.

Please don't forget to update your config file with the STOP_NMI
option removal

Reviewed by: jhb
Tested by: pho, bz, rink
Approved by: re (kib)

- Remove the bogus idle thread state code. This may have a race in it
and it only optimized out an ipi or mwait in very few cases.
- Skip the adaptive idle code when running on SMT or HTT cores. This
just wastes cpu time that could be used on a busy thread on the same
core.
- Rename CG_FLAG_THREAD to CG_FLAG_SMT to be more descriptive. Re-use
CG_FLAG_THREAD to mean SMT or HTT.

Sponsored by: Nokia

Initial suspend/resume support for amd64.

This code is heavily inspired by Takanori Watanabe's experimental SMP patch
for i386 and large portion was shamelessly cut and pasted from Peter Wemm's
AP boot code.

as suggested by jhb@, panic in case the ncpus == 0.
it helps to catch bugs in the callers.

Approved by: kib (mentor)
MFC after: 5 days

Fix range-check error introduced in r182292. Also do not do anything
if all processors in the map are not available, simply return.

Approved by: kib (mentor)
MFC after: 1 week

Whitespace tweak.

Adjust the license statement to more closely match a standard 3-clause BSD
license.

MFC after: 3 days

- Only count the number of CPUs in the rendezvous map once rather than
doing it on every CPU.
- Use CPU_ABSENT() rather than pcpu_find() to determine if a CPU is not
present.
- Count up to mp_maxid rather than MAXCPU when iterating over CPUs to
match the rest of the code in the kernel.

MFC after: 1 week

Allow a rendezvous with just a specified CPU too.

Make the API work in the non-smp case too so that a kernel module
can work the same regardless of whether or not it is loaded on a SMP
kernel or not.

In keeping with style(9)'s recommendations on macros, use a ';'
after each SYSINIT() macro invocation. This makes a number of
lightweight C parsers much happier with the FreeBSD kernel
source, including cflow's prcc and lxr.

MFC after: 1 month
Discussed with: imp, rink

- Add the missing '2' case to the switch table for kern.smp.topology and
assign it to create the flat 'none' topology where all cpus are scheduled
as if they are equal and unrelated.

- Remove the old smp cpu topology specification with a new, more flexible
tree structure that encodes the level of cache sharing and other
properties.
- Provide several convenience functions for creating one and two level
cpu trees as well as a default flat topology. The system now always
has some topology.
- On i386 and amd64 create a seperate level in the hierarchy for HTT
and multi-core cpus. This will allow the scheduler to intelligently
load balance non-uniform cores. Presently we don't detect what level
of the cache hierarchy is shared at each level in the topology.
- Add a mechanism for testing common topologies that have more information
than the MD code is able to provide via the kern.smp.topology tunable.
This should be considered a debugging tool only and not a stable api.

Sponsored by: Nokia

A few whitespace fixes.

Initial checkin for rmlock (read mostly lock) a multi reader single writer
lock optimized for almost exclusive reader access. (see also rmlock.9)

TODO:
Convert to per cpu variables linkerset as soon as it is available.
Optimize UP (single processor) case.

This is a follow-up, cleaning-up commit about recent changes involving
topology foo functions.
Working at the patch for topology problems in ia32/amd64 evicted some
problems regarding functions ordering in the SI_SUB_CPU family of
SYSINIT'ed subsystems.
In order to avoid problems with new modified to involved functions, a
correct ordering is not semantically specified for SI_SUB_CPU functions
(for a larger view of the issue please visit:
http://lists.freebsd.org/pipermail/freebsd-current/2007-July/075409.html )

Discussed with: peter
Tested by: kris, Rui Paulo <rpaulo@FreeBSD.org>
Approved by: jeff
Approved by: re

Tweak the low-level MI SMP code some:
- Use cpu_spinwait() in the spin loops in stop_cpus(), restart_cpus(), and
smp_rendezvous_action().
- Remove unneeded acq memory barriers in stop_cpus(), restart_cpus(), and
smp_rendezvous_action().
- Add an additional synch point in smp_rendezvous() to ensure that all the
CPUs will always see an up-to-date value of smp_rv_setup_func.

Reviewed by: attilio
Approved by: re (kensmith)
Tested on: alpha, amd64, i386, sparc64 SMP (for several years)

Commit 14/14 of sched_lock decomposition.
- Use thread_lock() rather than sched_lock for per-thread scheduling
sychronization.
- Use the per-process spinlock rather than the sched_lock for per-process
scheduling synchronization.

Tested by: kris, current@
Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc.
Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)

Instead of doing comparisons using the pcpu area to see if
a thread is an idle thread, just see if it has the IDLETD
flag set. That flag will probably move to the pflags word
as it's permenent and never chenges for the life of the
system so it doesn't need locking.

Rename the KDB_STOP_NMI kernel option to STOP_NMI and make it apply to all
IPI_STOP IPIs.
- Change the i386 and amd64 MD IPI code to send an NMI if STOP_NMI is
enabled if an attempt is made to send an IPI_STOP IPI. If the kernel
option is enabled, there is also a sysctl to change the behavior at
runtime (debug.stop_cpus_with_nmi which defaults to enabled). This
includes removing stop_cpus_nmi() and making ipi_nmi_selected() a
private function for i386 and amd64.
- Fix ipi_all(), ipi_all_but_self(), and ipi_self() on i386 and amd64 to
properly handle bitmapped IPIs as well as IPI_STOP IPIs when STOP_NMI is
enabled.
- Fix ipi_nmi_handler() to execute the restart function on the first CPU
that is restarted making use of atomic_readandclear() rather than
assuming that the BSP is always included in the set of restarted CPUs.
Also, the NMI handler didn't clear the function pointer meaning that
subsequent stop and restarts could execute the function again.
- Define a new macro HAVE_STOPPEDPCBS on i386 and amd64 to control the use
of stoppedpcbs[] and always enable it for i386 and amd64 instead of
being dependent on KDB_STOP_NMI. It works fine in both the NMI and
non-NMI cases.

Second part of commit for moving KDB_STOP_NMI from opt_global.h to
opt_kdb.h.

Found by: kris
Approved by: re

Implement an alternate method to stop CPUs when entering DDB. Normally we use
a regular IPI vector, but this vector is blocked when interrupts are disabled.
With "options KDB_STOP_NMI" and debug.kdb.stop_cpus_with_nmi set, KDB will
send an NMI to each CPU instead. The code also has a context-stuffing
feature which helps ddb extract the state of processes running on the
stopped CPUs.

KDB_STOP_NMI is only useful with SMP and complains if SMP is not defined.
This feature only applies to i386 and amd64 at the moment, but could be
used on other architectures with the appropriate MD bits.

Submitted by: ups

/* -> /*- for copyright notices, minor format tweaks as necessary

Move 4bsd specific experimental IP code into the 4bsd file.
Move the sysctls into kern.sched

*Blush* forgot to test non SMP builds.. oddly enough some UP code (particularly
in the acpi code) seems to want this in a UP build. (I guess so you can have
a sigle kernel module that works for both)

Give the 4bsd scheduler the ability to wake up idle processors
when there is new work to be done.

MFC after: 5 days

s/smp_rv_mtx/smp_ipi_mtx/g

Requested by: jhb

Commit Doug White and Alan Cox's fix for the cross-ipi smp deadlock.
We were obtaining different spin mutexes (which disable interrupts after
aquisition) and spin waiting for delivery. For example, KSE processes
do LDT operations which use smp_rendezvous, while other parts of the
system are doing things like tlb shootdowns with a different mutex.

This patch uses the common smp_rendezvous mutex for all MD home-grown
IPIs that spinwait for delivery. Having the single mutex means that
the spinloop to aquire it will enable interrupts periodically, thus
avoiding the cross-ipi deadlock.

Obtained from: dwhite, alc
Reviewed by: jhb

Don't keep evaluating our own cpu mask..
it's not likely to have changed....

Move the CPU newbus attachment to i386 legacy. The acpi_cpu device will
become just "cpu" and provide attachments in the !legacy case.

Tested by: des

Change the type of the various CPU masks to cpumask_t. Note that as
long as there are still explicit uses of int, whether in types or
in function names (such as atomic_set_int() in sched_ule.c), we can
not change cpumask_t to be anything other than u_int. See also the
commit log for sys/sys/types.h, revision 1.84.

Add powerpc to temporary fix. The new cpu device claims all
'generic' OpenFirmware nexus nodes, since it uses bus_generic_probe.
Maybe the cpu device probe should be MD.

This is a temporary fix to solve a regression issue on sparc64 that
is caused by the way sparc64 registers its CPUs. Nate will work on
a real fix shortly.

Approved by: njl

Hook CPUs up to newbus. CPUs will ultimately be a bus driver so that
multiple CPU-specific drivers can attach. This is a work in progress
so children aren't supported yet.

Help from: jhb

- Move smp_topology to subr_smp.c so that it is defined on all architectures.

Introduce mp_maxcpus which can be used by libkvm utils to find out
how many CPUs the system was compiled for.
Export the variable via a sysctl node 'kern.smp.maxcpus' as well.

Export a few SMP related symbols in UP kernels as well. This is needed to
aid other kernel code, especially code which can be in a module such as
the acpi_cpu(4) driver, to work properly with both SMP and UP kernels.
The exported symbols include mp_ncpus, all_cpus, mp_maxid, smp_started, and
the smp_rendezvous() function. This also means that CPU_ABSENT() is now
always implemented the same on all kernels.

Approved by: re (scottl)

- Split cpu_mp_probe() into two parts. cpu_mp_setmaxid() is still called
very early (SI_SUB_TUNABLES - 1) and is responsible for setting mp_maxid.
cpu_mp_probe() is now called at SI_SUB_CPU and determines if SMP is
actually present and sets mp_ncpus and all_cpus. Splitting these up
allows an architecture to probe CPUs later than SI_SUB_TUNABLES by just
setting mp_maxid to MAXCPU in cpu_mp_setmaxid(). This could allow the
CPU probing code to live in a module, for example, since modules
sysinit's in modules cannot be invoked prior to SI_SUB_KLD. This is
needed to re-enable the ACPI module on i386.
- For the alpha SMP probing code, use LOCATE_PCS() instead of duplicating
its contents in a few places. Also, add a smp_cpu_enabled() function
to avoid duplicating some code. There is room for further code
reduction later since much of this code is also present in cpu_mp_start().
- All archs besides i386 still set mp_maxid to the same values they set it
to before this change. i386 now sets mp_maxid to MAXCPU.

Tested on: alpha, amd64, i386, ia64, sparc64
Approved by: re (scottl)

Ensure that mp_ncpus is set to 1 if mp_cpu_probe() fails.

Change all SYSCTLS which are readonly and have a related TUNABLE
from CTLFLAG_RD to CTLFLAG_RDTUN so that sysctl(8) can provide
more useful error messages.

Document some sysctl variables.

Submitted by: hmp

Use __FBSDID().

Move the _oncpu entry from the KSE to the thread.
The entry in the KSE still exists but it's purpose will change a bit
when we add the ability to lock a KSE to a cpu.

- Move p->p_sigmask to td->td_sigmask. Signal masks will be per thread with
a follow on commit to kern_sig.c
- signotify() now operates on a thread since unmasked pending signals are
stored in the thread.
- PS_NEEDSIGCHK moves to TDF_NEEDSIGCHK.

Move a bunch of flags from the KSE to the thread.
I was in two minds as to where to put them in the first case..
I should have listenned to the other mind.

Submitted by: parts by davidxu@
Reviewed by: jeff@ mini@

Add a tunable kern.smp.disabled for disabling explicitly smp on an smp
kernel.

Completely redo thread states.

Reviewed by: davidxu@freebsd.org

Part 1 of KSE-III

The ability to schedule multiple threads per process
(one one cpu) by making ALL system calls optionally asynchronous.
to come: ia64 and power-pc patches, patches for gdb, test program (in tools)

Reviewed by: Almost everyone who counts
(at various times, peter, jhb, matt, alfred, mini, bernd,
and a cast of thousands)

NOTE: this is still Beta code, and contains lots of debugging stuff.
expect slight instability in signals..

Updated a doubly stale comment about signotify(). Fixed a nearby long line.

Change callers of mtx_init() to pass in an appropriate lock type name. In
most cases NULL is passed, but in some cases such as network driver locks
(which use the MTX_NETWORK_LOCK macro) and UMA zone locks, a name is used.

Tested on: i386, alpha, sparc64

- Remove a semi-colon from after SYSINIT that was introduced in rev. 1.163.

Remove __P.

Add needed includes of machine/smp.h, remove nested include in sys/smp.h
so that inlines in machine/smp.h can use variables declared in sys/smp.h.

Add a new variable mp_maxid. This is used so that per cpu datastructures may
be allocated as arrays indexed by the cpu id. Previously the only reliable
way to know the max cpu id was through MAXCPU. mp_ncpus isn't useful here
because cpu ids may be sparsely mapped, although x86 and alpha do not do this.

Also, call cpu_mp_probe much earlier so the max cpu id is known before the VM
starts up. This is intended to help support per cpu queues for the new
allocator, but may be useful elsewhere.

Reviewed by: jake
Approved by: jake

Fix forward_roundrobin(). It was mistakenly using the cpu number as
though it was a mask. As a result, we sent AST IPI's to the wrong
cpu and/or left out some.

Spotted by: jake

Overhaul the per-CPU support a bit:

- The MI portions of struct globaldata have been consolidated into a MI
struct pcpu. The MD per-CPU data are specified via a macro defined in
machine/pcpu.h. A macro was chosen over a struct mdpcpu so that the
interface would be cleaner (PCPU_GET(my_md_field) vs.
PCPU_GET(md.md_my_md_field)).
- All references to globaldata are changed to pcpu instead. In a UP kernel,
this data was stored as global variables which is where the original name
came from. In an SMP world this data is per-CPU and ideally private to each
CPU outside of the context of debuggers. This also included combining
machine/globaldata.h and machine/globals.h into machine/pcpu.h.
- The pointer to the thread using the FPU on i386 was renamed from
npxthread to fpcurthread to be identical with other architectures.
- Make the show pcpu ddb command MI with a MD callout to display MD
fields.
- The globaldata_register() function was renamed to pcpu_init() and now
init's MI fields of a struct pcpu in addition to registering it with
the internal array and list.
- A pcpu_destroy() function was added to remove a struct pcpu from the
internal array and list.

Tested on: alpha, i386
Reviewed by: peter, jake

Don't remove the tentative declaration. It's the only one...

Pointy hat: marcel (self-sponsoring)

Make smp_started volatile in sys/smp.h and remove the volatile
declaration in subr_smp.c. This solves a compile problem with
gcc 3.0.1 (ia64 cross-build).

Reviewed: jhb

KSE Milestone 2
Note ALL MODULES MUST BE RECOMPILED
make the kernel aware that there are smaller units of scheduling than the
process. (but only allow one thread per process at this time).
This is functionally equivalent to teh previousl -current except
that there is a thread associated with each process.

Sorry john! (your next MFC will be a doosie!)

Reviewed by: peter@freebsd.org, dillon@freebsd.org

X-MFC after: ha ha ha ha

- Close races with signals and other AST's being triggered while we are in
the process of exiting the kernel. The ast() function now loops as long
as the PS_ASTPENDING or PS_NEEDRESCHED flags are set. It returns with
preemption disabled so that any further AST's that arrive via an
interrupt will be delayed until the low-level MD code returns to user
mode.
- Use u_int's to store the tick counts for profiling purposes so that we
do not need sched_lock just to read p_sticks. This also closes a
problem where the call to addupc_task() could screw up the arithmetic
due to non-atomic reads of p_sticks.
- Axe need_proftick(), aston(), astoff(), astpending(), need_resched(),
clear_resched(), and resched_wanted() in favor of direct bit operations
on p_sflag.
- Fix up locking with sched_lock some. In addupc_intr(), use sched_lock
to ensure pr_addr and pr_ticks are updated atomically with setting
PS_OWEUPC. In ast() we clear pr_ticks atomically with clearing
PS_OWEUPC. We also do not grab the lock just to test a flag.
- Simplify the handling of Giant in ast() slightly.

Reviewed by: bde (mostly)

- Split out the support for per-CPU data from the SMP code. UP kernels
have per-CPU data and gdb on the i386 at least needs access to it.
- Clean up includes in kern_idle.c and subr_smp.c.

Reviewed by: jake

Overhaul of the SMP code. Several portions of the SMP kernel support have
been made machine independent and various other adjustments have been made
to support Alpha SMP.

- It splits the per-process portions of hardclock() and statclock() off
into hardclock_process() and statclock_process() respectively. hardclock()
and statclock() call the *_process() functions for the current process so
that UP systems will run as before. For SMP systems, it is simply necessary
to ensure that all other processors execute the *_process() functions when the
main clock functions are triggered on one CPU by an interrupt. For the alpha
4100, clock interrupts are delievered in a staggered broadcast fashion, so
we simply call hardclock/statclock on the boot CPU and call the *_process()
functions on the secondaries. For x86, we call statclock and hardclock as
usual and then call forward_hardclock/statclock in the MD code to send an IPI
to cause the AP's to execute forwared_hardclock/statclock which then call the
*_process() functions.
- forward_signal() and forward_roundrobin() have been reworked to be MI and to
involve less hackery. Now the cpu doing the forward sets any flags, etc. and
sends a very simple IPI_AST to the other cpu(s). AST IPIs now just basically
return so that they can execute ast() and don't bother with setting the
astpending or needresched flags themselves. This also removes the loop in
forward_signal() as sched_lock closes the race condition that the loop worked
around.
- need_resched(), resched_wanted() and clear_resched() have been changed to take
a process to act on rather than assuming curproc so that they can be used to
implement forward_roundrobin() as described above.
- Various other SMP variables have been moved to a MI subr_smp.c and a new
header sys/smp.h declares MI SMP variables and API's. The IPI API's from
machine/ipl.h have moved to machine/smp.h which is included by sys/smp.h.
- The globaldata_register() and globaldata_find() functions as well as the
SLIST of globaldata structures has become MI and moved into subr_smp.c.
Also, the globaldata list is only available if SMP support is compiled in.

Reviewed by: jake, peter
Looked over by: eivind

Make the ap_boot_mtx mutex static.

Blow away the panic mutex in favor of using a single atomic_cmpset() on a
panic_cpu shared variable. I used a simple atomic operation here instead
of a spin lock as it seemed to be excessive overhead. Also, this can avoid
recursive panics if, for example, witness is broken.

Rename the IPI API from smp_ipi_* to ipi_* since the smp_ prefix is just
"redundant noise" and to match the IPI constant namespace (IPI_*).

Requested by: bde

Remove the BETTER_CLOCK #ifdef's. The code is on by default and is here
to stay for the foreseeable future.

OK'd by: peter (the idea)

Add an MI API for sending IPI's. I used the same API present on the alpha
because:
- it used a better namespace (smp_ipi_* rather than *_ipi),
- it used better constant names for the IPI's (IPI_* rather than
X*_OFFSET), and
- this API also somewhat exists for both alpha and ia64 already.

Rework the witness code to work with sx locks as well as mutexes.
- Introduce lock classes and lock objects. Each lock class specifies a
name and set of flags (or properties) shared by all locks of a given
type. Currently there are three lock classes: spin mutexes, sleep
mutexes, and sx locks. A lock object specifies properties of an
additional lock along with a lock name and all of the extra stuff needed
to make witness work with a given lock. This abstract lock stuff is
defined in sys/lock.h. The lockmgr constants, types, and prototypes have
been moved to sys/lockmgr.h. For temporary backwards compatability,
sys/lock.h includes sys/lockmgr.h.
- Replace proc->p_spinlocks with a per-CPU list, PCPU(spinlocks), of spin
locks held. By making this per-cpu, we do not have to jump through
magic hoops to deal with sched_lock changing ownership during context
switches.
- Replace proc->p_heldmtx, formerly a list of held sleep mutexes, with
proc->p_sleeplocks, which is a list of held sleep locks including sleep
mutexes and sx locks.
- Add helper macros for logging lock events via the KTR_LOCK KTR logging
level so that the log messages are consistent.
- Add some new flags that can be passed to mtx_init():
- MTX_NOWITNESS - specifies that this lock should be ignored by witness.
This is used for the mutex that blocks a sx lock for example.
- MTX_QUIET - this is not new, but you can pass this to mtx_init() now
and no events will be logged for this lock, so that one doesn't have
to change all the individual mtx_lock/unlock() operations.
- All lock objects maintain an initialized flag. Use this flag to export
a mtx_initialized() macro that can be safely called from drivers. Also,
we on longer walk the all_mtx list if MUTEX_DEBUG is defined as witness
performs the corresponding checks using the initialized flag.
- The lock order reversal messages have been improved to output slightly
more accurate file and line numbers.

Kill the 4MB kernel limit dead. [I hope :-)].
For UP, we were using $tmp_stk as a stack from the data section. If the
kernel text section grew beyond ~3MB, the data section would be pushed
beyond the temporary 4MB P==V mapping. This would cause the trampoline
up to high memory to fault. The hack workaround I did was to use all of
the page table pages that we already have while preparing the initial
P==V mapping, instead of just the first one.
For SMP, the AP bootstrap process suffered the same sort of problem and
got the same treatment.

MFC candidate - this breaks on 4.x just the same..

Thanks to: Richard Todd <rmtodd@ichotolot.servalan.com>

Activate USER_LDT by default. The new thread libraries are going to
depend on this. The linux ABI emulator tries to use it for some linux
binaries too. VM86 had a bigger cost than this and it was made default
a while ago.

Reviewed by: jhb, imp

Woops, remove an obsolete reference to gd_cpu_lockid.

Change and clean the mutex lock interface.

mtx_enter(lock, type) becomes:

mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks)
mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized)

similarily, for releasing a lock, we now have:

mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN.
We change the caller interface for the two different types of locks
because the semantics are entirely different for each case, and this
makes it explicitly clear and, at the same time, it rids us of the
extra `type' argument.

The enter->lock and exit->unlock change has been made with the idea
that we're "locking data" and not "entering locked code" in mind.

Further, remove all additional "flags" previously passed to the
lock acquire/release routines with the exception of two:

MTX_QUIET and MTX_NOSWITCH

The functionality of these flags is preserved and they can be passed
to the lock/unlock routines by calling the corresponding wrappers:

mtx_{lock, unlock}_flags(lock, flag(s)) and
mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN
locks, respectively.

Re-inline some lock acq/rel code; in the sleep lock case, we only
inline the _obtain_lock()s in order to ensure that the inlined code
fits into a cache line. In the spin lock case, we inline recursion and
actually only perform a function call if we need to spin. This change
has been made with the idea that we generally tend to avoid spin locks
and that also the spin locks that we do have and are heavily used
(i.e. sched_lock) do recurse, and therefore in an effort to reduce
function call overhead for some architectures (such as alpha), we
inline recursion for this case.

Create a new malloc type for the witness code and retire from using
the M_DEV type. The new type is called M_WITNESS and is only declared
if WITNESS is enabled.

Begin cleaning up some machdep/mutex.h code - specifically updated the
"optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN
and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently
need those.

Finally, caught up to the interface changes in all sys code.

Contributors: jake, jhb, jasone (in no particular order)

Remove some leftovers from the CMAP* stuff in globaldata and the
BSP and AP startup.

Move the setting of curproc to idleproc up earlier in ap_init(). The
problem is that a mutex lock, prior to this change, is acquired before
the curproc is set to idleproc, so we mess ourselves up by calling
the mutex lock routine with curproc == NULL.

Moving it up after the aps_ready spin-wait has us hopefully setting it
after idleproc is setup.

Solved by: jake (the allmighty) :-)

Defer assignment of low level interrupt handlers for PCI interrupts
described in the MP table until something asks for the interrupt number
later on.

Convert all simplelocks to mutexes and remove the simplelock implementations.

- Relocate portions of this file to get it into an order closer to that of
the alpha mp_machdep.c.
- Proc locking.
- Catch up to the P_FOO -> PS_FOO proc flags changes.
- Stick ap_init()'s prototype with the other prototypes.
- Remove the Xforwardirq IPI.
- Remove unused simplelocks.
- Don't try to psignal() from forward_statclock(), but set the appropriate
signal pending flag in p_sflag instead.
- Add in KTR_SMP tracepoints for various SMP functions. (Brought over
from the alpha port)

Make intr_nesting_level per-process, rather than per-cpu. Setup
interrupt threads to run with it always >= 1, so that malloc can
detect M_WAITOK from "interrupt" context. This is also necessary
in order to context switch from sched_ithd() directly.

Reviewed By: peter

Remove APIC_INTR_DIAGNOSTIC - this has been disabled for some time now.
Remove some leftovers of removed SMP options.

Remove the per-cpu pages used for copy and zero-ing pages of memory
for SMP; just use the same ones as UP. These weren't used without
holding Giant anyway, and the routines that use them would have to
be protected from pre-emption to avoid migrating cpus.

apic_itrace_splz[] is unused

Protect p_stat and p_oncpu with sched_lock in forward_signal().

Change return ??? to return -1 in some #if 0'ed code.

Use PCPU_GET, PCPU_PTR and PCPU_SET to access all per-cpu variables
other then curproc.

Fix a warning. The type of globaldata.gd_prvspace has changed.

This is kind of a nasty hack, but it appears to solve the Compaq DL360
SMP problem. Compaq, in their infinite wisdom, forgot to put the IO apic
intpin #0 connection to the 8259 PIC into the mptable. This hack is to
look and see if intpin #0 has *no* table entry and adds a fake ExtInt
entry for the remap routines to use. isa/clock.c will still test the
interrupts. This entry is only ever used on an already broken system.

Cleanup some leftover lint from the old interrupt system.
Also, while here, run up to 32 interrupt sources on APIC systems.
Normalize INTREN/INTRDIS so they are the same on both UP and SMP systems
rather than sometimes a macro, and sometimes a function.

Reviewed by: jhb, jakeb

Don't wait forever for CPUs to stop or restart. Instead, give up after a
timeout. If DIAGNOSTIC is turned on, then display a message to the console
with a map of which CPUs failed to stop or restart. This gives an SMP box
at least a fighting chance of getting into DDB if one of the other CPUs has
interrupts disabled.

Catch up to moving headers:
- machine/ipl.h -> sys/ipl.h
- machine/mutex.h -> sys/mutex.h

- Change fast interrupts on x86 to push a full interrupt frame and to
return through doreti to handle ast's. This is necessary for the
clock interrupts to work properly.
- Change the clock interrupts on the x86 to be fast instead of threaded.
This is needed because both hardclock() and statclock() need to run in
the context of the current process, not in a separate thread context.
- Kill the prevproc hack as it is no longer needed.
- We really need Giant when we call psignal(), but we don't want to block
during the clock interrupt. Instead, use two p_flag's in the proc struct
to mark the current process as having a pending SIGVTALRM or a SIGPROF
and let them be delivered during ast() when hardclock() has finished
running.
- Remove CLKF_BASEPRI, which was #ifdef'd out on the x86 anyways. It was
broken on the x86 if it was turned on since cpl is gone. It's only use
was to bogusly run softclock() directly during hardclock() rather than
scheduling an SWI.
- Remove the COM_LOCK simplelock and replace it with a clock_lock spin
mutex. Since the spin mutex already handles disabling/restoring
interrupts appropriately, this also lets us axe all the *_intr() fu.
- Back out the hacks in the APIC_IO x86 cpu_initclocks() code to use
temporary fast interrupts for the APIC trial.
- Add two new process flags P_ALRMPEND and P_PROFPEND to mark the pending
signals in hardclock() that are to be delivered in ast().

Submitted by: jakeb (making statclock safe in a fast interrupt)
Submitted by: cp (concept of delaying signals until ast())

Remove the NCPU, NAPIC, NBUS, NINTR config options. Make NAPIC,
NBUS, NINTR dynamic and set NCPU to a maximum of 16 under SMP.

Reviewed by: peter

Clean up process accounting some more. Unfortunately, it is still not
quite right on i386 as the CPU who runs statclock() doesn't have a valid
clockframe to calculate statistics with.

When doing statistics for statclock on other CPU's, use the other CPUs'
idleproc pointers instead of our own for comparisons.

Submitted by: tegge

Remove an unneeded extern declaration of cp_time.

Really fix USER_LDT. (Don't use currentldt as an L-value.)

Major update to the way synchronization is done in the kernel. Highlights
include:

* Mutual exclusion is used instead of spl*(). See mutex(9). (Note: The
alpha port is still in transition and currently uses both.)

* Per-CPU idle processes.

* Interrupts are run in their own separate kernel threads and can be
preempted (i386 only).

Partially contributed by: BSDi (BSD/OS)
Submissions by (at least): cp, dfr, dillon, grog, jake, jhb, sheldonh

Clean up some low level bootstrap code:

- stop using the evil 'struct trapframe' argument for mi_startup()
(formerly main()). There are much better ways of doing it.
- do not use prepare_usermode() - setregs() in execve() will do it
all for us as long as the p_md.md_regs pointer is set. (which is
now done in machdep.c rather than init_main.c. The Alpha port did it
this way all along and is much cleaner).
- collect all the magic %cr0 etc register settings into one place and
have the AP's call that instead of using magic numbers (!!) that keep
changing over and over again.
- Make it safe to call kthread_create() earlier, including during the
device probe sequence. It doesn't need the callback mechanism that
NetBSD's version uses.
- kthreads created this way are root-less as they exist before the root
filesystem is mounted. init(1) is set up so that it aquires the root
pointers prior to running. If other kthreads want filesystem acccess
we can make this code more generic.
- set all threads start times once we have decided what time it is.
- init uses a trampoline rather than the evil prepare_usermode() hack.
- kern_descrip.c has a couple of tweaks to deal with forking when there
is no rootdir or cwd etc.
- adjust the early SYSINIT() sequence so that a few prereqisites are in
place. eg: make sure the run queue is initialized before doing forks.

With this, the USB code can easily create a kthread to do the device
tree discovery. (I have tested it, it works nicely).

There are still some open issues before this is truely useful.
- tsleep() does not like working before the clock is running. It
sort-of tries to spin wait, but it can do more useful things now.
- stopping a kthread in kld code at unload time is "interesting" but
we have a solution for that.

The Alpha code needs no changes for this. It already uses pretty much the
same strategies, but a little cleaner.

Don't skip IOAPIC id conflict detection when only one pci bus is present.
PR: 20312
Reviewed by: Steve Roome <steve@sse0691.bri.hp.com>

Be more verbose when changing APIC ID on an IO APIC.

Don't allow cpu entries in the MP table to contain APIC IDs out of range.

Don't write outside array boundaries if an IO APIC entry in the MP table
contains an APIC ID out of range.

Assign APIC IDs for all IO APICs according to section 3.6.6 in the
Intel MP spec:

- If the current APIC ID on an IO APIC doesn't conflict with other
IO APICs or CPUs, that APIC ID should be used. The copy of the MP
table must be updated if the corresponding APIC ID in the MP table
is different.

- If the current APIC ID was in conflict with other units, the
corresponding APIC ID specified in the MP table is checked for conflict.

- If a conflict is still found then fall back to using a new unique ID.
The copy of the MP table must be updated.

- IDs out of range is considered to be in conflict.

During these operations, the IO_TO_ID array cannot be used, since any
conflict would have caused information loss. The array is then corrected,
since all APIC ID conflicts should have been resolved.

PR: 20312, 18919

Further fixes for multiple-IO-APIC systems from Tor Egge:

Further experimentation showed that some Dell 2450 machines with the
prevention kludge installed still got T_RESERVED traps. CPU interrupt
vector 0x7A was observed to be triggered. This might have been the
bitwise OR of two different vectors sent from each of the IOAPICs at
the same time.

IOAPIC #0: 0x68 --> irq 8: RTC timer interrupt
IOAPIC #1: 0x32 --> irq 18: scsi host adapter or network interface
----
0x7a --> T_RESERVED

Both IOAPICs had ID 0.

Appendix B.3 in the MP spec indicates that the operating system is
responsible for assigning unique IDs to the IOAPICs.

The enclosed patch programs the IOAPIC IDs according to the IOAPIC
entries in the MP table.

Submitted by: tegge

Commit major SMP cleanups and move the BGL (big giant lock) in the
syscall path inward. A system call may select whether it needs the MP
lock or not (the default being that it does need it).

A great deal of conditional SMP code for various deadended experiments
has been removed. 'cil' and 'cml' have been removed entirely, and the
locking around the cpl has been removed. The conditional
separately-locked fast-interrupt code has been removed, meaning that
interrupts must hold the CPL now (but they pretty much had to anyway).
Another reason for doing this is that the original separate-lock for
interrupts just doesn't apply to the interrupt thread mechanism being
contemplated.

Modifications to the cpl may now ONLY occur while holding the MP
lock. For example, if an otherwise MP safe syscall needs to mess with
the cpl, it must hold the MP lock for the duration and must (as usual)
save/restore the cpl in a nested fashion.

This is precursor work for the real meat coming later: avoiding having
to hold the MP lock for common syscalls and I/O's and interrupt threads.
It is expected that the spl mechanisms and new interrupt threading
mechanisms will be able to run in tandem, allowing a slow piecemeal
transition to occur.

This patch should result in a moderate performance improvement due to
the considerable amount of code that has been removed from the critical
path, especially the simplification of the spl*() calls. The real
performance gains will come later.

Approved by: jkh
Reviewed by: current, bde (exception.s)
Some work taken from: luoqi's patch

Allow SMP systems with an MCA bus to work properly.

Reviewed by: peter

Allow SMP && NCPU == 1 to work. From now on, there's no restriction on the
value of NCPU relative to the number of cpus physically present, the actual
number of cpus utilized will be the smaller of the two.

ISA device drivers use the ISA source interrupt number in locations where
the low level interrupt handler number should be used. Change
setup_apic_irq_mapping() to allocate low level interrupt handler X (Xintr${X})
for any ISA interrupt X mentioned in the MP table.

Remove an assumption in the driver for the system clock (clock.c) that
interrupts mentioned in the MP table as delivered to IOAPIC #0 intpin Y
is handled by low level interrupt handler Y (Xintr${Y}) but don't assume
that low level interrupt handler 0 (Xintr0) is used.

Don't allocate two low level interrupt handlers for the system clock.
Reviewed by: NOKUBI Hirotaka <hnokubi@yyy.or.jp>

Moved scheduling-related code to kern_synch.c so that it is easier to fix
and extend. The new function containing the code is named schedclock()
as in NetBSD, but it has slightly different semantics (it already handles
incrementation of p->p_cpticks, and it should handle any calling frequency).

Agreed with in principle by: dufault

Eliminate remaining part of incorrect PCI bus numbering sanity check on systems with more than one PCI bus.

Zap unneeded #includes

Submitted by: phk

Set up FPU state on the AP.

Tested by: phk

$Id$ -> $FreeBSD$

Merge the cons.c and cons.h to the best of my ability. alpha may or
may not compile, I can't test it.

Implement an all-CPU shootdown-style rendezvous facility. This allows
the caller to specify a function to be guarded between an entry and exit
barrier, as well as pre- and post-barrier functions.

The primary use for this function is synchronised update of per-cpu private
data. The implementation is almost (but not quite) MI; with a better
mechanism for masking per-CPU interrupts it could probably be hoisted.

Reviewed by: peter (partially)

Changes in the way that the APs are started appears to have removed the
problem with having more CPUs than NCPU.

PR: kern/4255
Submitted by: peter

Do not setup 4M pdir until all APs are up.

Remove an unnecessary panic when sparse PCI bus numbering is encountered.
This is found eg. on some Compaq Proliant systems.

Submitted by: peter

Unifdef VM86.

Reviewed by: silence on on -current

Unbreak VESA on SMP.

Make sure the mem_range_AP_init() prototype is seen where it's needed, and
#ifdef SMP around it for fun.

Add a hook that can be called to initialise a slave processor's memory
range attributes after they have been extracted from the master.

Hook up the i686 MP code to do this for each AP.

Be more careful about printing the default memory type for the i686.

Suggestions from: luoqi

Enable vmspace sharing on SMP. Major changes are,
- %fs register is added to trapframe and saved/restored upon kernel entry/exit.
- Per-cpu pages are no longer mapped at the same virtual address.
- Each cpu now has a separate gdt selector table. A new segment selector
is added to point to per-cpu pages, per-cpu global variables are now
accessed through this new selector (%fs). The selectors in gdt table are
rearranged for cache line optimization.
- fask_vfork is now on as default for both UP and SMP.
- Some aio code cleanup.

Reviewed by: Alan Cox <alc@cs.rice.edu>
John Dyson <dyson@iquest.net>
Julian Elischer <julian@whistel.com>
Bruce Evans <bde@zeta.org.au>
David Greenman <dg@root.com>

Backout early start of APs since it caused some machines to hang.

Add prototype for wait_ap().

Let BSP wait until all APs are initialized.

Disable the mtrr copy calls, it doesn't work with the i686_mem.c stuff.
This should make it compile/link again.

The magic "no-cpu" cpu number is 0xff. Don't misrepresent cpu
numbers as chars or use bogus casts in an attempt to unmisrepresnt
them. In top, don't assume that 0xff is the only negative cpu
number when cpu numbers are (mis)represented.

Don't call assign_apic_irq with a value for irq that is out of range.

Introduce machine-dependent macro pgtok() to convert page count to number
of kilobytes. Its definition for each architecture could be optimized to
avoid potential numerical overflows.

Hide access to vmspace:vm_pmap with inline function vmspace_pmap(). This
is the preparation step for moving pmap storage out of vmspace proper.

Reviewed by: Alan Cox <alc@cs.rice.edu>
Matthew Dillion <dillon@apollo.backplane.com>

Fix warnings in preparation for adding -Wall -Wcast-qual to the
kernel compile

Make more messages conditional on bootverbose

Silence warnings.

The "easy" fixes for compiling the kernel -Wunused: remove unreferenced static
and local variables, goto labels, and functions declared but not defined.

Attempt to handle interrupts delivered to all IO APICs by using the first
IO APIC with a sufficient number of pins.

Staticize.

mp_machdep.c: Set a vector to boot code (PC-98).
locore.s: Tell the bios to warmboot next time (PC-98).

PC-98 doesn't have CMOS ram.

BIOS ROM base address is 0xe8000 on PC-98.

Maintain a mapping from irq number to (ioapic number, int pin) tuple,
and use this when masking/unmasking interrupts.

Maintain a mapping from (iopaic number, int pin) tuple to irq number,
and use this when configuring devices and programming the ioapics.

Previous code assumed that irq number was equal to int pin number, and
that the ioapic number was 0.

Don't let an AP enter _cpu_switch before all local apics are initialized.

Fixed printf format errors. Only one left in LINT on i386's.

Presently there is only one `currentldt' variable for all cpus
in a SMP system. Unexpected things could happen if each cpu
has a different ldt setting and one cpu tries to use value
of currentldt set by another cpu.

The fix is to move currentldt to the per-cpu area. It includes
patches I filed in PR i386/6219 which are also user ldt related.

PR: i386/7591, i386/6219
Submitted by: Luoqi Chen <luoqi@watermarkgroup.com>

pmap.c:
Cast pointers to (vm_offset_t) instead of to (u_long) (as before) or to
(uintptr_t)(void *) (as would be more correct). Don't cast vm_offset_t's
to (u_long) just to do arithmetic on them.

mp_machdep.c:
Cast pointers to (uintptr_t) instead of to (u_long). Don't forget
to cast pointers to (void *) first or to recover from integral
possible integral promotions, although this is too much work for
machine-dependent code.

vm code generally avoids warnings for pointer vs long size mismatches
by using vm_offset_t to represent pointers; pmap.c often uses plain
`unsigned int' instead of vm_offset_t and didn't use u_long elsewhere,
but this style was messed up by code apparently imported from mp_machdep.c.

Add forwarding of roundrobin to other cpus. This gives a more regular
update of cpu usage as shown by top when one process is cpu bound
(no system calls) while the system is otherwise idle (except for top).

Don't attempt to switch to the BSP in boot(). If the system was idle when
an interrupt caused a panic, this won't work. Instead, switch to the BSP
in cpu_reset.

Remove some spurious forward_statclock/forward_hardclock warnings.

For SMP, use prv_PPAGE1/prv_PMAP1 instead of PADDR1/PMAP1.
get_ptbase and pmap_pte_quick no longer generates IPIs.
This should reduce the number of IPIs during heavy paging.

Attempt to set write combining mode for graphics devices.

Use real types for the SMP pages being allocated rather than arrays of
ints. Remove some no longer needed casts. Initialize the per-cpu
global data area using the structs rather than knowing too much about
layout, alignment, etc.

Make a kernel version of the timer* functions called timerval* to be
more consistent.

OK'ed by: bde

Add two workarounds for broken MP tables:

- Attempt to handle PCI devices where the interrupt is
an ISA/EISA interrupt according to the mp table.

- Attempt to handle multiple IO APIC pins connected to
the same PCI or ISA/EISA interrupt source. Print a
warning if this happens, since performance is suboptimal.
This workaround is only used for PCI devices.

With these two workarounds, the -SMP kernel is capable of running on
my Asus P/I-P65UP5 motherboard when version 1.4 of the MP table is disabled.

The APs now reload the interrupt descriptor table pointer after
f00f_hack has run.

Use the global r_idt descriptor in f00f_hack when in SMP mode,
so the APs find the relocated interrupt descriptor table.

Submitted by: Partially from David A Adkins <adkin003@tc.umn.edu>

When entering the apic version of slow interrupt handler, level
interrupts are masked, and EOI is sent iff the corresponding ISR bit
is set in the local apic. If the CPU cannot obtain the interrupt
service lock (currently the global kernel lock) the interrupt is
forwarded to the CPU holding that lock.

Clock interrupts now have higher priority than other slow interrupts.

Forward the signal if the process runs on a different CPU. This reduces
the signal handling latency for cpu-bound processes that performs very
few system calls.

The IPI for forcing an additional software trap is no longer dependent upon
BETTER_CLOCK being defined.

Reduce timeout before assuming that forwarding of hardclock or softclock
failed. Don't complain on forwarding failure, unless
BETTER_CLOCK_DIAGNOSTIC is defined.

1) Use a more consistent page wait methodology.
2) Do not unnecessarily force page blocking when paging
pages out.
3) Further improve swap pager performance and correctness,
including fixing the paging in progress deadlock (except
in severe I/O error conditions.)
4) Enable vfs_ioopt=1 as a default.
5) Fix and enable the page prezeroing in SMP mode.

All in all, SMP systems especially should show a significant
improvement in "snappyness."

Staticize.

Add support for low resolution SMP kernel profiling.

- A nonprofiling version of s_lock (called s_lock_np) is used
by mcount.

- When profiling is active, more registers are clobbered in
seemingly simple assembly routines. This means that some
callers needed to save/restore extra registers.

- The stack pointer must have space for a 'fake' return address
in idle, to avoid stack underflow.

Don't forward hardclock or statclock to stopped cpus. Disable forwarding
when a panic has occured.

Add needed #include.

Problem found by: Bruce Evans <bde@zeta.org.au>

The improvements to clock statistics by Tor Egge
Wrappered and enabled by the define BETTER_CLOCK (on by default in smpyests.h)

Reviewed by: smp@csn.net
Submitted by: Tor Egge <Tor.Egge@idi.ntnu.no>

Use UPAGES when setting up private pages for SMP (which includes idle stack).

Removed unused #includes.

Try and fix some style problems

Convert the VM86 option from a global option to an option only depended
on by the files that use it. Changing the VM86 option now only causes
a recompile of a dozen files or so rather than the entire kernel.

It is possible that MB's with really broken bios's not set up more of
the mtrr registers. This just fills in more of the registers.

Make sure that the memory type registers are the same for each CPU
in a P6 SMP system. Some MB bios'es don't set the registers up correctly
for the AP's. Additionally, set the memory between 0xa0000 and 0xbffff
as write combining.

Implement the parts needed for VM86 under SMP.

Add support for more than 1 page of idle process stack on SMP systems.

General cleanup of the lock pushdown code. They are grouped and enabled
from machine/smptests.h:

#define PUSHDOWN_LEVEL_1
#define PUSHDOWN_LEVEL_2
#define PUSHDOWN_LEVEL_3
#define PUSHDOWN_LEVEL_4_NOT

Cleanup.

Move closer to supporting VM86 under SMP.

LINT now compiles but doesn't link. Other link-time breakage for LINT
is now visible (SMP is incompatible with SIMPLELOCK_DEBUG).
Submitted by: jlemon

Debug version of simple_lock. This will store the CPU id of the
holding CPU along with the lock. When a CPU fails to get the lock
it compares its own id to the holder id. If they are the same it
panic()s, as simple locks are binary, and this would cause a deadlock.

Controlled by smptests.h: SL_DEBUG, ON by default.

Some minor cleanup.

Another round of lock pushdown.
Add a simplelock to deal with disable_intr()/enable_intr() as used in UP kernel.
UP kernel expects that this is enough to guarantee exclusive access to
regions of code bracketed by these 2 functions.
Add a simplelock to bracket clock accesses in clock.c: clock_lock.

Help from: Bruce Evans <bde@zeta.org.au>

Correct some things I forgot about until it was too late with smp_active.
smp_active = 1 used to indicate that the system had frozen previously
started AP's, while smp_active = 0 was "AP's not yet started". I have split
this into smp_started (which is set when the AP's come online), and
smp_active is left for turning on/off AP scheduling.

Clean up the SMP AP bootstrap and eliminate the wretched idle procs.

- We now have enough per-cpu idle context, the real idle loop has been
revived (cpu's halt now with nothing to do).
- Some preliminary support for running some operations outside the
global lock (eg: zeroing "free but not yet zeroed pages") is present
but appears to cause problems. Off by default.
- the smp_active sysctl now behaves differently. It's merely a 'true/false'
option. Setting smp_active to zero causes the AP's to halt in the idle
loop and stop scheduling processes.
- bootstrap is a lot safer. Instead of sharing a statically compiled in
stack a number of times (which has caused lots of problems) and then
abandoning it, we use the idle context to boot the AP's directly. This
should help >2 cpu support since the bootlock stuff was in doubt.
- print physical apic id in traps.. helps identify private pages getting
out of sync. (You don't want to know how much hair I tore out with this!)

More cleanup to follow, this is more of a checkpoint than a
'finished' thing.

Removed a bogus comment.

A clean fix for the spl "deadlock before smp_active" problem.

Added a new variable, 'bsp_apic_ready', which is set as soon as the bootstrap
CPU has initialized its local APIC. Conditionalize the GENSPLR functions
to call ss_lock ONLY after bsp_apic_ready is TRUE; This should prevent
any problems with races between the time the 1st AP becomes ready and the
time smp_active is set.

Made PEND_INTS default.
Made NEW_STRATEGY default.
Removed misc. old cruft.

Centralized simple locks into mp_machdep.c
Centralized simple lock macros into param.h

More cleanup in the direction of making splxx()/cpl MP-safe.

Preperation for moving cpl into critical region access.
Several new fine-grained locks.
New FAST_INTR() methods:
- separate simplelock for FAST_INTR, no more giant lock.
- FAST_INTR()s no longer checks ipending on way out of ISR.
sio made MP-safe (I hope).

Cheap fix for kern/4255.
If the problem is seen this fix suggests a compile-time work-around then panics.

Some fixes towards making "default configs" work again.
Still not fixed, no idea why.

Debug help from: "Thomas D. Dean" <tomdean@ix.netcom.com>

Converted the TEST_LOPRIO code to default.
Created mplock functions that save/restore NO registers.
Minor cleanup.

Modified the PEND_INTS algorithm to fix the ISA INT loss problem.

Noticed by: dave adkins <adkin003@gold.tc.umn.edu> and others.

mpapic.c & mp_machdep:
- removed TEST_ALTTIMER.
- removed APIC_PIN0_TIMER.
- removed TIMER_ALL.

mplock.s:
- minor update of try_mplock for new algorithm where a CPU uses try_mplock
instead of get_mplock in the ISRs.

New simple_lock code in asm:
- s_lock_init()
- s_lock()
- s_lock_try()
- s_unlock()

Created lock for IO APIC and apic_imen (SMP version of imen)
- imen_lock

Code to use imen_lock for access from apic_ipl.s and apic_vector.s.
Moved this code *outside* of mp_lock.

It seems to work!!!

Developed a new strategy for handling the 8254/8259/APIC issue.

Minor cleanup.
Pass string arg to apic_dump.
Moved bootverbose printing of SMP enabled INTs from clock.c to autoconf.c

Removed unused #includes.

Added code to support #define APIC_PIN0_TIMER.
This code ALWAYS runs the 8254 timer thru the 8259 ICU.
It depricates the usage of "options SMP_TIMER_NC" in the config file.

Split TEST_CPUSTOP code into CPUSTOP_ON_DDBBREAK and mainline code.

printf cleanup.

Hopefully fix a few problems that could cause hangs in SMP mode.
1) Make sure that the region mapped by a 4MB page is
properly aligned.
2) Don't turn on the PG_G flag in locore for SMP. I plan
to do that later in startup anyway.
3) Make sure the 2nd processor has PSE enabled, so that 4MB
pages don't hose it.

We don't use PG_G yet on SMP -- there is work to be done to make that
work correctly. It isn't that important anyway...

new code to control other CPUs: stop_cpus()/restart_cpus()/_Xstopcpu
this code is controlled by smptests.h: TEST_CPUSTOP, OFF by default

new code for handling mixed-mode 8259/APIC programming without 'ExtInt'
this code is controlled by smptests.h: TEST_ALTTIMER, ON by default

General cleanup of APIC code.
stop_cpus()/restart_cpus() STILL not working!

stop_cpus(), currently BROKEN! (turned off in smptests.h by default).
restart_cpus(), currently BROKEN! (turned off in smptests.h by default).

Added POST code output to various points of the startup code.

General cleanup.

New functions to stop/start CPUs via IPIs:

- int stop_cpus( u_int map );
- int restart_cpus( u_int map );

Turned off by default, enabled via smptests.h:TEST_CPUSTOP.
Current version has a BUG, perhaps a deadlock?

Program lint1 to handle NMIs.

Till now NMIs would be ignored. Now an NMI is caught by the BSP.
APs still ignore NMI, am working on code to allow a CPU to stop other CPUs
via an IPI.

Merged/renamed functions:

- get_isa_apic_mask() -> isa_apic_mask()
- get_isa_apic_irq() && get_eisa_apic_irq() -> isa_apic_pin()
- get_pci_apic_irq() -> pci_apic_pin()

Ensure that the boot CPU honours write protection in kernel mode.
This fixes one of the problems noted in PR kern/3688.

Fix calculation of initial mplock value.
We now use LOGICAL, not PHYSICAL, IDs to calculate the mplock.

Fixed breakage for "default" configurations in mptable_pass1().

Preliminary support for per-cpu data pages.

This eliminates a lot of #ifdef SMP type code. Things like _curproc reside
in a data page that is unique on each cpu, eliminating the expensive macros
like: #define curproc (SMPcurproc[cpunumber()])

There are some unresolved bootstrap and address space sharing issues at
present, but Steve is waiting on this for other work. There is still some
strictly temporary code present that isn't exactly pretty.

This is part of a larger change that has run into some bumps, this part is
standalone so it should be safe. The temporary code goes away when the
full idle cpu support is finished.

Reviewed by: fsmp, dyson

Change isa_device.h to intr_machdep.h

Code such as apic_base[APIC_ID] converted to lapic__id

Changes to pmap.c for lapic_t lapic && ioapic_t ioapic pointers,
currently equal to apic_base && io_apic_base, will stand alone with the
private page mapping.

minor style police (recent divergence from KNF code)

Nuke the printing of the unredirect message unless bootverbose.

Added a test called 'LATE_START'.

This is now the default, it delays most of the MP startup to the function
machdep.c:cpu_startup(). It should be possible to move the 2 functions
found there (mp_start() & mp_announce()) even further down the path once
we know exactly where that should be...

Help from: Peter Wemm <peter@spinner.dialix.com.au>

Broke up parse_mp_table() into 2 passes:
- The 1st (preparse_mp_table()) counts the number of cpus, busses, etc. and
records the LOCAL and IO APIC addresses.
- The 2nd pass (parse_mp_table()) does the actual parsing of info and recording
into the incore MP table.

This will allow us to defer the 2nd pass untill malloc() & private pages
are available (but thats for another day!).

Now that panic() is properly printing messages for early SMP panics all
the 'printf("..."); panic("\n")' sections are returned to 'panic("...")'.

Convert all:
panic( "xxxxx\n" );

to:
printf( "xxxxx\n" );
panic( "\n" );

For some as yet undetermined reason the argument to panic() is often NOT
printed, and the system sometimes hangs before reaching the panic printout.
So we hopefully at least print some useful info before the hang, as oppossed to
leaving the user clueless as to what has happened.

fix bug in get_isa_apic_mask() where EISA bus was ignored.

Submitted by: Peter Wemm <peter@spinner.DIALix.COM>

Code to handle SMP/APIC_IO mapping of ISA INTs to APIC pins above IRQ15.

- doesn't break my system.
- NOT yet verified on the affected motherboard.

Submitted by: "John S. Dyson" <toor@dyson.iquest.net>

new function to turn an APIC pin# into an INT mask.
added missing APIC_IO define.

Submitted by: "John S. Dyson" <toor@dyson.iquest.net>

fixed spelling error.

Submitted by: Bruce Albrecht <bruce@zuhause.mn.org>

Enabled 'FIX_MP_TABLE_WORKS' code.
This code re-numbers PCI busses in the MP table to match PCI semantics
when the MP BIOS fails to do it properly.

Reviewed by: Peter Wemm <peter@spinner.DIALix.COM>

removed all the TEST_UPPERPRIO crud.

remove all the SMP_INVLTLB defines, making the code default for APIC_IO.

Reviewed by: informal discussion with Peter Wemm <peter@spinner.DIALix.COM>

informal discussion between Bruce Evans <bde@zeta.org.au>,
Peter Wemm <peter@spinner.DIALix.COM>, Steve Passe <smp@csn.net>

removed all the IPI_INTS code.
made the XFAST_IPI32 code default, renaming Xfastipi32 to Xinvltlb.

Man the liferafts! Here comes the long awaited SMP -> -current merge!

There are various options documented in i386/conf/LINT, there is more to
come over the next few days.

The kernel should run pretty much "as before" without the options to
activate SMP mode.

There are a handful of known "loose ends" that need to be fixed, but
have been put off since the SMP kernel is in a moderately good condition
at the moment.

This commit is the result of the tinkering and testing over the last 14
months by many people. A special thanks to Steve Passe for implementing
the APIC code!