non-386 atomic_load_acq(). %eax is an input since its value is used in
the cmpxchg instruction, but we don't care what value it is, so setting
it to a specific value is just wasteful. Thus, it is being used without
being initialized as the warning stated, but it is ok for it to be used
because its value isn't important. Thus, we are only sort of lying when
we say it is an output only operand.
- Add "cc" to the clobber list for atomic_load_acq() since the cmpxchgl
changes ZF.
compiling errors where gcc would run out of registers.
- Add "cc" to the list of clobbers for micro-ops where we perform
instructions that alter %eflags.
- Use xchgl instead of cmpxchgl to release a spin lock. This could allow
for more efficient register allocation as we no longer mandate that %eax
be used.
- Reenable the optimized mutex micro-ops in the non-i386 case.
that modules can call.
- Remove the old gcc <= 2.8 versions of the atomic ops.
- Resort the order of some things in the file so that there is only
one #ifdef for KLD_MODULE, and so that all WANT_FUNCTIONS stuff is
moved to the bottom of the file.
- Remove ATOMIC_ACQ_REL() and just use explicit macros instead.
implement memory fences for the 486+. The 386 still uses versions w/o
memory fences as all operations on the 386 are not program ordered.
The 386 versions are not MP safe.
__FreeBSD_version 500015 can be used to detect their disappearance.
- Move the symbols for SMP_prvspace and lapic from globals.s to
locore.s.
- Remove globals.s with extreme prejudice.
symbols in globals.s.
PCPU_GET(name) returns the value of the per-cpu variable
PCPU_PTR(name) returns a pointer to the per-cpu variable
PCPU_SET(name, val) sets the value of the per-cpu variable
In general these are not yet used, compatibility macros remain.
Unifdef SMP struct globaldata, this makes variables such as cpuid
available for UP as well.
Rebuilding modules is probably a good idea, but I believe old
modules will still work, as most of the old infrastructure
remains.
as multi-processor kernels. The old way made it difficult for kernel
modules to be portable between uni-processor and multi-processor
kernels. It is no longer necessary to jump through hoops.
- always load %fs with the private segment on entry to the kernel
- change the type of the self referntial pointer from struct privatespace
to struct globaldata
- make the globaldata symbol have value 0 in all cases, so the symbols
in globals.s are always offsets, not aliases for fields in globaldata
- define the globaldata space used for uniprocessor kernels in C, rather
than assembler
- change the assmebly language accessors to use %fs, add a macro
PCPU_ADDR(member, reg), which loads the register reg with the address
of the per-cpu variable member
To use it, some dll is needed. And currently, the dll is only for NetBSD.
So one more kernel module is needed.
For more infomation,
http://chiharu.haun.org/peace/ .
Reviewed by: bp
variables from i386 assembly language. The syntax is PCPU(member)
where member is the capitalized name of the per-cpu variable, without
the gd_ prefix. Example: movl %eax,PCPU(CURPROC). The capitalization
is due to using the offsets generated by genassym rather than the symbols
provided by linking with globals.o. asmacros.h is the wrong place for
this but it seemed as good a place as any for now. The old implementation
in asnames.h has not been removed because it is still used to de-mangle
the symbols used by the C variables for the UP case.
the witness code is compiled in. Without this, the witness code doesn't
notice that sched_lock is released by fork_trampoline() and thus gets all
confused about spin lock order later on.
calling the C functions mtx_enter_hard() and mtx_exit_hard() clobbers them.
Note that %eax is also not call safe, but it is already clobbered due to
cmpxchg. However, now we are back to not compiling again, so these macros
are still left disabled for now.
that of MTX_EXIT. Don't assume that the reg parameter to MTX_ENTER
holds curproc, load it explicitly. Put semi-colons at the end of
the macros to be more consistent and so its harder to forget them
when these change.
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.
mpapic.c. This gives us the benefit of C type checking. These functions
are not called in any critical paths and are not used by the interrupt
routines.
spending, which was unused now that all software interrupts have
their own thread. Make the legacy schednetisr use an atomic op
for setting bits in the netisr mask.
Reviewed by: jhb
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
MPLOCKED macro
(2) Use decimal 12 rather than hex 0xc in an addl
(3) Implement MTX_ENTER for the I386_CPU case
(4) Use semi-colons between instructions to allow MTX_ENTER
and MTX_ENTER_WITH_RECURSION to be assembled
(5) Use incl instead of incw to increment the recusion count
(6) 10 is not a valid label, use 7, 8 and 9 rather than 8, 9 and 10
(7) Sort numeric labels
Submitted by: bde (2, 4, and 5)
process is on the alternate stack or not. For compatibility
with sigstack(2) state is being updated if such is needed.
We now determine whether the process is on the alternate
stack by looking at its stack pointer. This allows a process
to siglongjmp from a signal handler on the alternate stack
to the place of the sigsetjmp on the normal stack. When
maintaining state, this would have invalidated the state
information and causing a subsequent signal to be delivered
on the normal stack instead of the alternate stack.
PR: 22286
-current and RELENG_4 with GENERIC.
NKPT is the number of initial bootstrap page table pages we create for
the kernel during startup. Once VM is up, we resize it as needed, but
with 4G ram, the size of the vm_page_t structures was pushing it over
the limit. The fact that trimmed down kernels boot on 4G ram machines
suggests that we were pretty close to the edge.
The "30" is arbitary, but smaller than the 'nkpt' variable on all
machines that I checked.
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.
counter register in-CPU.
This is to be used as a fast "timer", where linearity is more important
than time, and multiple lines in the linearity caused by multiple CPUs
in an SMP machine is not a problem.
This adds no code whatsoever to the FreeBSD kernel until it is actually
used, and then as a single-instruction inline routine (except for the
80386 and 80486 where it is some more inline code around nanotime(9).
Reviewed by: bde, kris, jhb
syscall compare against a variable sv_minsigstksz in struct
sysentvec as to properly take the size of the machine- and
ABI dependent struct sigframe into account.
The SVR4 and iBCS2 modules continue to have a minsigstksz of
8192 to preserve behavior. The real values (if different) are
not known at this time. Other ABI modules use the real
values.
The native MINSIGSTKSZ is now defined as follows:
Arch MINSIGSTKSZ
---- -----------
alpha 4096
i386 2048
ia64 12288
Reviewed by: mjacob
Suggested by: bde
This code has help us comprehence ACPI spec .
Contributors of this code is as follows(except for FreeBSD commiter):
Yasuo Yokoyama,
Munehiro Matsuda,
and ALL acpi-jp@jp.freebsd.org people.
Thanks.
R.I.P.
Previously we had to include <machine/param.h> or <sys/param.h> bogusly
due to the fact that <sys/socket.h> CMSG macros needed the ALIGN macro,
which was defined in param.h. However, including param.h was a disaster
for namespace pollution.
This solution, as contributed by shin a while ago, fixes it elegantly
by wrapping the definitions around some namespace pollution preventer
definitions.
This patch was long overdue.
This should allow any network programmer to use <sys/socket.h> as
before.
PR: 19971, 20530
Submitted by: Martin Kaeske <MartinKaeske@lausitz.net>
Mark Andrews <Mark.Andrews@nominum.com>
Patch submitted by: shin
Reviewed by: bde
because it only takes a struct tag which makes it impossible to
use unions, typedefs etc.
Define __offsetof() in <machine/ansi.h>
Define offsetof() in terms of __offsetof() in <stddef.h> and <sys/types.h>
Remove myriad of local offsetof() definitions.
Remove includes of <stddef.h> in kernel code.
NB: Kernelcode should *never* include from /usr/include !
Make <sys/queue.h> include <machine/ansi.h> to avoid polluting the API.
Deprecate <struct.h> with a warning. The warning turns into an error on
01-12-2000 and the file gets removed entirely on 01-01-2001.
Paritials reviews by: various.
Significant brucifications by: bde
type of software interrupt. Roughly, what used to be a bit in spending
now maps to a swi thread. Each thread can have multiple handlers, just
like a hardware interrupt thread.
- Instead of using a bitmask of pending interrupts, we schedule the specific
software interrupt thread to run, so spending, NSWI, and the shandlers
array are no longer needed. We can now have an arbitrary number of
software interrupt threads. When you register a software interrupt
thread via sinthand_add(), you get back a struct intrhand that you pass
to sched_swi() when you wish to schedule your swi thread to run.
- Convert the name of 'struct intrec' to 'struct intrhand' as it is a bit
more intuitive. Also, prefix all the members of struct intrhand with
'ih_'.
- Make swi_net() a MI function since there is now no point in it being
MD.
Submitted by: cp
more include file including <sys/proc.h>, but there still is this wonky
and (causes warnings on i386) reference in globals.h.
CURTHD is now defined in <machine/globals.h> as well. The correct thing
to do is provide a platform function for this.
(a NetBSD port for NEC PC-98x1 machines). They are ncv for NCR 53C500,
nsp for Workbit Ninja SCSI-3, and stg for TMC 18C30 and 18C50.
I thank NetBSD/pc98 and bsd-nomads people.
Obtained from: NetBSD/pc98
reducues the maintenance load for the mutex code. The only MD portions
of the mutex code are in machine/mutex.h now, which include the assembly
macros for handling mutexes as well as optionally overriding the mutex
micro-operations. For example, we use optimized micro-ops on the x86
platform #ifndef I386_CPU.
- Change the behavior of the SMP_DEBUG kernel option. In the new code,
mtx_assert() only depends on INVARIANTS, allowing other kernel developers
to have working mutex assertiions without having to include all of the
mutex debugging code. The SMP_DEBUG kernel option has been renamed to
MUTEX_DEBUG and now just controls extra mutex debugging code.
- Abolish the ugly mtx_f hack. Instead, we dynamically allocate
seperate mtx_debug structures on the fly in mtx_init, except for mutexes
that are initiated very early in the boot process. These mutexes
are declared using a special MUTEX_DECLARE() macro, and use a new
flag MTX_COLD when calling mtx_init. This is still somewhat hackish,
but it is less evil than the mtx_f filler struct, and the mtx struct is
now the same size with and without mutex debugging code.
- Add some micro-micro-operation macros for doing the actual atomic
operations on the mutex mtx_lock field to make it easier for other archs
to override/optimize mutex ops if needed. These new tiny ops also clean
up the code in some places by replacing long atomic operation function
calls that spanned 2-3 lines with a short 1-line macro call.
- Don't call mi_switch() from mtx_enter_hard() when we block while trying
to obtain a sleep mutex. Calling mi_switch() would bogusly release
Giant before switching to the next process. Instead, inline most of the
code from mi_switch() in the mtx_enter_hard() function. Note that when
we finally kill Giant we can back this out and go back to calling
mi_switch().
in most of the atomic operations. Now for these operations, you can
use the normal atomic operation, you can use the operation with a read
barrier, or you can use the operation with a write barrier. The function
names follow the same semantics used in the ia64 instruction set. An
atomic operation with a read barrier has the extra suffix 'acq', due to
it having "acquire" semantics. An atomic operation with a write barrier
has the extra suffix 'rel'. These suffixes are inserted between the
name of the operation to perform and the typename. For example, the
atomic_add_int() function now has 3 variants:
- atomic_add_int() - this is the same as the previous function
- atomic_add_acq_int() - this function combines the add operation with a
read memory barrier
- atomic_add_rel_int() - this function combines the add operation with a
write memory barrier
- Add 'ptr' to the list of types that we can perform atomic operations
on. This allows one to do atomic operations on uintptr_t's. This is
useful in the mutex code, for example, because the actual mutex lock is
a pointer.
- Add two new operations for doing loads and stores with memory barriers.
The new load operations use a read barrier before the load, and the
new store operations use a write barrier after the load. For example,
atomic_load_acq_int() will atomically load an integer as well as
enforcing a read barrier.
write caching is disabled on both SCSI and IDE disks where large
memory dumps could take up to an hour to complete.
Taking an i386 scsi based system with 512MB of ram and timing (in
seconds) how long it took to complete a dump, the following results
were obtained:
Before: After:
WCE TIME WCE TIME
------------------ ------------------
1 141.820972 1 15.600111
0 797.265072 0 65.480465
Obtained from: Yahoo!
Reviewed by: peter
as inline functions, renaming them to __uint16_swap_uint32,
__uint8_swap_uint32 and __uint8_swap_uint16.
Doing it properly suggested by: msmith
Reviewed by: msmith
This shouldn't affect the alpha or ia64, since they don't have a
variable named astpending. The alpha still has 2 declarations of
this nonexistent variable.
Replace all in-tree uses with <sys/mouse.h> which repo-copied a few
moments ago from src/sys/i386/include/mouse.h by peter.
This is also the appropriate fix for exo-tree sources.
Put warnings in <machine/mouse.h> to discourage use.
November 15th 2000 the warnings will be converted to errors.
January 15th 2001 the <machine/mouse.h> files will be removed.
Replace all in-tree uses with necessary subset of <sys/{fb,kb,cons}io.h>.
This is also the appropriate fix for exo-tree sources.
Put warnings in <machine/console.h> to discourage use.
November 15th 2000 the warnings will be converted to errors.
January 15th 2001 the <machine/console.h> files will be removed.
check in the [basic.link] section of the C++ standard wrong. gcc-2.7.2.3
apparently doesn't do the check, so the bug doesn't affect RELENG_3.
PR: 16170, 21427
Submitted by: Max Khon <fjoe@lark.websci.ru> (i386 version)
Discussed with: jdp
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())
- Make softinterrupts (SWI's) almost completely MI, and divorce them
completely from the x86 hardware interrupt code.
- The ihandlers array is now gone. Instead, there is a MI shandlers array
that just contains SWI handlers.
- Most of the former machine/ipl.h files have moved to a new sys/ipl.h.
- Stub out all the spl*() functions on all architectures.
Submitted by: dfr
OsdSleepUsec(), SleepOp corresponds to OsdSleep() by reading ACPICA
source code.
- Add OsdSleepUsec() which uses DELAY() simply.
- Change unit of acpi_sleep() argument; microseconds to milliseconds.
drivers (again). These drivers have not compiled for 5-6 months.
Now that the new sound code supports MIDI, the major reason we had for
reviving it is gone. It is a far better investment polishing the new
midi code than trying to keep this on life support. Come 5.0-REL, if
there are major shortcomings in the pcm sound driver then maybe we can
rethink this, but until then we should focus on pcm.
Remember, these have not been compilable since ~April-May this year.
that it's enabled in acpireg.h only if DIAGNOSTIC option is specified.
ACPICA OSD functions will be compiled in machine/acpi_machdep.c again
tentatively (if DIAGNOSTIC option is specified).
# Should we have acpica_osd.c ?
avoid power on again problem after acpi_soft_off() calling.
- Implement SleepOp/StallOp in AML interpreter. Also provide ACPICA
compatibility.
- Minor changes on __inline function declaration in acpica_osd.h
(obtained from NetBSD porting).
- Move all register I/O into acpi_io.c
- Move event handling into acpi_event.c
- Reorganise headers into acpivar/acpireg/acpiio
- Move find-RSDT and find-ACPI-owned-memory into acpi_machdep
- Allocate all resources (except those detailed only by AML)
as real resources. Add infrastructure that will make adding
resource support to AML code easy.
- Remove all ACPI #ifdefs in non-ACPI code
- Removed unnecessary includes
- Minor style and commenting fixes
Reviewed by: iwasaki
i386/isa/pcibus.c. This gets -current running again on multiple host->pci
machines after the most recent nexus commits. I had discussed this with
Mike Smith, but ended up doing it slightly differently to what we
discussed as it turned out cleaner this way. Mike was suggesting creating
a new resource (SYS_RES_PCIBUS) or something and using *_[gs]et_resource(),
but IMHO that wasn't ideal as SYS_RES_* is meant to be a global platform
property, not a quirk of a given implementation. This does use the ivar
methods but does so properly. It also now prints the physical pci bus that
a host->pci bridge (pcib) corresponds to.
newbus for referencing device interrupt handlers.
- Move the 'struct intrec' type which describes interrupt sources into
sys/interrupt.h instead of making it just be a x86 structure.
- Don't create 'ithd' and 'intrec' typedefs, instead, just use 'struct ithd'
and 'struct intrec'
- Move the code to translate new-bus interrupt flags into an interrupt thread
priority out of the x86 nexus code and into a MI ithread_priority()
function in sys/kern/kern_intr.c.
- Remove now-uneeded x86-specific headers from sys/dev/ata/ata-all.c and
sys/pci/pci_compat.c.
macros that expand to pass filename and line number information. This is
necessary since we're using inline functions instead of macros now.
Add const to the filename pointers passed througout the mtx and witness
code.
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
- The "Osd*" stuff went away from acpi driver code, use the bus_space
functions directly instead.
- Fix minor english bugs.
acpi_registers_input -> acpi_register_input
acpi_registers_output -> acpi_register_output
- Remove all magic numbers for the sleeping states. We now have
#defines for these.
- NULL is treated the same as the return from aml_get_rootname in
aml_find_from_namespace().
Suggested by: msmith
Thanks mike!
suggested fix in PR 12378.
Keep track of all existing pmaps independent of existing processes.
This allows for a process to temporarily connect to a different address
space without the risk of missing an update of the original address space if
the kernel grows.
pmap_pinit2() is no longer needed on the i386 platform but is left as a
stub until the alpha pmap code is updated.
PR: 12378
- 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 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
display control by apm -d.
- Remove APM_DEBUG to avoid re-build kernel with such a unspported optioin.
- Introduce new denug flag `debug.apm_debug' which can be controlled by
sysctl interface and loader by setting like "debug.apm_debug=1", you
will get debug messages from APM driver.
- Add some enhancements from linux on display control by apm -d. I'm
expecting that we can see some improvements on some laptops where
apm -d doesn't work correctly so far.
Reviewed by: -mobile and -current folks (no objection)
Suggested by: Susumu WAKABAYASHI <susumu@wakabaya.net>
errors were normally harmless because they were in unreachable code
and gcc apparently doesn't check the syntax inside asm statements
that it optimizes away.
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
to various pmap_*() functions instead of looking up the physical address
and passing that. In many cases, the first thing the pmap code was doing
was going to a lot of trouble to get back the original vm_page_t, or
it's shadow pv_table entry.
Inspired by: John Dyson's 1998 patches.
Also:
Eliminate pv_table as a seperate thing and build it into a machine
dependent part of vm_page_t. This eliminates having a seperate set of
structions that shadow each other in a 1:1 fashion that we often went to
a lot of trouble to translate from one to the other. (see above)
This happens to save 4 bytes of physical memory for each page in the
system. (8 bytes on the Alpha).
Eliminate the use of the phys_avail[] array to determine if a page is
managed (ie: it has pv_entries etc). Store this information in a flag.
Things like device_pager set it because they create vm_page_t's on the
fly that do not have pv_entries. This makes it easier to "unmanage" a
page of physical memory (this will be taken advantage of in subsequent
commits).
Add a function to add a new page to the freelist. This could be used
for reclaiming the previously wasted pages left over from preloaded
loader(8) files.
Reviewed by: dillon
specifies the instruction's operation size. GCC will default to 32-bit
operands reguardless of the prototype (ie, formal parameters' type)
of an inline function.
same functionality. Sharing code should help cache issues.
Remove in_cksum_partial, since its not being used, and we now have
a way to compute partial checksums on mbuf chains.
- Add support for using the PCI BIOS functions for configuration space
accesses, and make this the default.
- Make PNPBIOS the default (obsoletes the PNPBIOS config option).
- Add two new boot-time tunables to disable each of the above.
