Stop attempting to use FADT legacy hardware flag, it is almost always
a lie.
Instead, unless user explicitly disabled the calibration, calibrate
against 8254 ISA clock. Then, obtain the rough value of the expected
TSC frequency from CPUID leafs 0x15/0x16 or even from the CPU
marketing name string. If calibration results look unbelievably bogus
comparing with CPUID leafs report, use CPUID one.
Intel does not recommend to use CPUID leaf 0x16 for the value of the
system time frequency, indeed the error there might be up to 1% which
e.g. makes ntpd give up. If ISA clock is present, we win, if not, we
get some frequency that allows the machine to boot without enormous
delay.
Next improvement would be to use HPET for re-calibration if we decided
that ISA clock gives bogus results, after HPETs are enumerated. This
is a much bigger change since we probably would need to re-evaluate
some constants depending on TSC frequency.
Reviewed by: emaste, jhb, scottl
Tested by: scottl
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D24426
If EOI suppression is supported but reported ioapic version is so old
that it does not has EOI register (weird virtualization setup), fix
Intel trick of eoi-ing by flipping pin type (edge/level) to account
for the disabled pin.
Reported by: Juniper
Reviewed by: jhb
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D23965
It does not serve any purpose now, the io apic id is not seen by
software, and some Intel documents claim that the register is
implemented for FUD reasons. More, renumbering seems to not work on
new Intel machines which actually have mismatched MADT and hw IDs.
On older machines where separate APIC bus existed, unique numbering of
all APICs was required for bus arbitration to work, but it is no
longer true (that machines were SMP from pre-Pentium IV era).
When matching PCIe IOAPIC device against MADT-enumerated IOAPICs,
compare io_apic_id from BAR against io_apic_id read from the
MADT-pointed register page.
Reviewed by: jhb
Tested by: flo (previous version), pho
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D23965
It seems that the newer Intel chipset did that, and Linux reads 8
bits. The only detail is that all seen datasheets, even under NDA,
claim that io apic id is 4 bits.
Submitted by: jeff
Reviewed by: jhb
Tested by: flo, pho
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D23965
r357614 added CTLFLAG_NEEDGIANT to make it easier to find nodes that are
still not MPSAFE (or already are but aren’t properly marked).
Use it in preparation for a general review of all nodes.
This is non-functional change that adds annotations to SYSCTL_NODE and
SYSCTL_PROC nodes using one of the soon-to-be-required flags.
Mark all obvious cases as MPSAFE. All entries that haven't been marked
as MPSAFE before are by default marked as NEEDGIANT
Approved by: kib (mentor, blanket)
Commented by: kib, gallatin, melifaro
Differential Revision: https://reviews.freebsd.org/D23718
When turning IBRS mitigation using sysctl, as opposed to loader tunable,
send IPI to tweak MSR on all cores. Right now code only performed MSR write
onr the CPU where sysctl was run.
Properly report hw.ibrs_active for IBRS_ALL. Split hw_ibrs_ibpb_active out
from ibrs_active, to keep the current semantic of guiding kernel entry and
exit handlers.
Reported and tested by: mav
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
This is SVM features word, the bit is defined in "PPR for AMD Family
17h Model 31h B0", document 55803 Rev 0.54.
N.B. GuesSpecCtl (no 't') is the spelling from the document.
Submitted by: Dmitry Luhtionov <dmitryluhtionov@gmail.com>
MFC after: 3 days
Returned value has type based on the argument, meaning consumers no longer
have to cast in the commmon case.
This commit keeps the kernel compilable without patching the rest.
In dmar_gas_uppermatch, skip searching a subtree if all its gaps-between-alloctions are too small.
Reviewed by: kib
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D23391
If package-level control is present, we default to using it. Per-core
software control may be enabled by setting the machdep.hwpstate_pkg_ctrl
tunable to "0" in loader.conf(5).
Per Intel SDM (Vol 3b Part 2), if HWP indicates EPP (energy-performance
preference) is not supported, the hardware instead uses the ENERGY_PERF_BIAS
MSR. In the epp sysctl handler, fall back to that MSR if HWP does not
support EPP and CPUID indicates the ENERGY_PERF_BIAS MSR is supported.
I don't know why a Skylake CPU with the HWP feature bit present would trap
on MSR reads of the HWP registers, but if this occurs, do not leave the
attach thread bound. This could conceivably cause reported hangs, although
I have no evidence that this is the cause.
Reported by: ae@, Andreas Nilsson <andrnils AT gmail.com>
X-MFC-With: r357002
Add a sysctl knob to allow users to re-enable it, and document the knob and
default in cpufreq.4. (While here, add a few unrelated updates to
cpufreq.4.)
It seems that the register value in some hardware simply reflects the
configured P-state. This results in an inadvertent and unintended outcome
where the P-state can only walk down, and then the driver becomes "stuck" in
the slowest possible P-state.
The Linux driver never consults this register, so that's some evidence that
ignoring the contents are relatively harmless.
PR: 234733
Reported by: sigsys AT gmail.com, Erich Dollanksy <freebsd.ed.lists AT
sumeritec.com>
After r355784 the td_oncpu field is no longer synchronized by the thread
lock, so the stack capture interrupt cannot be delievered precisely.
Fix this using a loop which drops the thread lock and restarts if the
wrong thread was sampled from the stack capture interrupt handler.
Change the implementation to use a regular interrupt instead of an NMI.
Now that we drop the thread lock, there is no advantage to the latter.
Simplify the KPIs. Remove stack_save_td_running() and add a return
value to stack_save_td(). On platforms that do not support stack
capture of running threads, stack_save_td() returns EOPNOTSUPP. If the
target thread is running in user mode, stack_save_td() returns EBUSY.
Reviewed by: kib
Reported by: mjg, pho
Tested by: pho
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D23355
These were all introduced in the initial import of hwpstate_intel(4).
Reported by: Coverity
CIDs: 1413161, 1413164, 1413165, 1413167
X-MFC-With: r357002
at the root of every subtree that changes in an insert or delete, and
only once, and ordered from the bottom of the tree to the top. For
intel_gas.c, the only user of RB_AUGMENT I can find, change the
augmenting routine so that it does not climb from entry to tree root
on every call, and remove a 'tree correcting' function that can be
supplanted by proper tree augmentation.
Reviewed by: kib
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D23189
If we're going to throttle user requested P-states, we should at least produce
a debug log line indicating the surprising behavior.
PR: inspired by 234733
DRIVER_MODULE does not actually define a MODULE_VERSION, which is required
to satisfy a MODULE_DEPENDency. Declare one explicitly in
hwpstate_intel(4).
Reported by: flo
X-MFC-With: r357002
Instead of waiting for pc_curthread which is overwritten by
init_secondary_tail(), wait for non-NULL pc_curpcb, to be set by the
first context switch.
Assert that pc_curpcb is not set too early.
Reported and tested by: rlibby
Reviewed by: markj, rlibby
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D23330
Intel Speed Shift is Intel's technology to control frequency in hardware,
with hints from software.
Let's get a working version of this in the tree and we can refine it from
here.
Submitted by: bwidawsk, scottph
Reviewed by: bcr (manpages), myself
Discussed with: jhb, kib (earlier versions)
With feedback from: Greg V, gallatin, freebsdnewbie AT freenet.de
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D18028
As a new x86 CPU vendor, Chengdu Haiguang IC Design Co., Ltd (Hygon)
is a joint venture between AMD and Haiguang Information Technology Co.,
Ltd., aims at providing x86 processors for China server market.
The first generation Hygon processor(Dhyana) shares most architecture
with AMD's family 17h, but with different CPU vendor ID("HygonGenuine")
and PCI vendor ID(0x1d94) and family series number 18h(Hygon negotiated
with AMD to confirm that only Hygon use family 18h).
To enable Hygon Dhyana support in FreeBSD, add new definitions
HYGON_VENDOR_ID("HygonGenuine") and X86_VENDOR_HYGON(0x1d94) to identify
Hygon Dhyana CPU.
Initialize the CPU features(topology, local APIC ext, MSI, TSC, hwpstate,
MCA, DEBUG_CTL, etc) for amd64 and i386 mode by sharing the code path of
AMD family 17h.
The changes have been applied on FreeBSD 13.0-CURRENT and tested
successfully on Hygon Dhyana processor.
References:
[1] Linux kernel patches for Hygon Dhyana, merged in 4.20:
https://git.kernel.org/tip/c9661c1e80b609cd038db7c908e061f0535804ef
[2] MSR and CPUID definition:
https://www.amd.com/system/files/TechDocs/54945_PPR_Family_17h_Models_00h-0Fh.pdf
Submitted by: Pu Wen <puwen@hygon.cn>
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D23163
is no longer used.
pc_curthread is set by cpu_switch after it stopped using the old
thread (or boot) stack. This makes the smp_after_idle_runnable()
function not dependent on the internals of the scheduler operations.
Reviewed by: markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D23276
off the stack, initialized to default values, and then filled in with
driver-specific values, all without having to worry about the numerous
other fields in the tag. The resulting template is then passed into
busdma and the normal opaque tag object created. See the man page for
details on how to initialize a template.
Templates do not support tag filters. Filters have been broken for many
years, and only existed for an ancient make/model of hardware that had a
quirky DMA engine. Instead of breaking the ABI/API and changing the
arugment signature of bus_dma_tag_create() to remove the filter arguments,
templates allow us to ignore them, and also significantly reduce the
complexity of creating and managing tags.
Reviewed by: imp, kib
Differential Revision: https://reviews.freebsd.org/D22906
s/BIT_NAND/BIT_ANDNOT/, and for CPU and DOMAINSET too. The actual
implementation is "and not" (or "but not"), i.e. A but not B.
Fortunately this does appear to be what all existing callers want.
Don't supply a NAND (not (A and B)) operation at this time.
Discussed with: jeff
Reviewed by: cem
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D22791
migitation is available in microcode and the operator has set
the sysctl to automatic mode.
Reported by: Coverity
CID: 1408334
MFC after: 3 days
Sponsored by: Intel
hardclock IPI is delivered.
In the current code after r355311, critical section is taken only
around hardclockintr() call, and sched_preempt() is called after the
section is exited. If we reschedule after exit, as we typically would
due to conditions that caused IPI, in ULE the runq tdq_ipipending is
not cleared, which blocks generation of further preempt IPIs.
Since all relatively modern (10 years) hardware has per-cpu event
timers, restoring the critical section conditionally does not affect
it.
Reported and tested by: cy
Diagnosed and reviewed by: jeff (previous version)
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D22716
They're in both the old and new places in HEAD for the moment for
discussion and transition. The old locations will be garbage collected
in 4 weeks. MFCs to 12 an 11 will keep the old and new for transition
purposes.
Reviewed by: kib
MFC after: 4 weeks
Sponsored by: Intel
Differential Revision: https://reviews.freebsd.org/D22590
Just a typo that Coverity identified.
Coverity also identified an unused store in the same functional area (x86 TAA
stuff), but this commit does not address that issue (CID 1408334).
Reported by: Coverity
CID: 1408328, 1408332
tightening constraints on busy as a precursor to lockless page lookup and
should largely be a NOP for these cases.
Reviewed by: alc, kib, markj
Differential Revision: https://reviews.freebsd.org/D22611
the sched_preempt() switch optimization and causes the sched lock to be dropped
and immediately reacquired.
Reviewed by: jhb, kib, mav, markj (with changes)
Differential Revision: https://reviews.freebsd.org/D22623
The header is abused for inclusion into userspace, and on stable
branches neither device_t nor bool types are not defined when used
from userspace.
Sponsored by: The FreeBSD Foundation
X-MFC after: now
Update the NetBSD Kernel Concurrency Sanitizer (KCSAN) runtime to work in
the FreeBSD kernel. It is a useful tool for finding data races between
threads executing on different CPUs.
This can be enabled by enabling KCSAN in the kernel config, or by using the
GENERIC-KCSAN amd64 kernel. It works on amd64 and arm64, however the later
needs a compiler change to allow -fsanitize=thread that KCSAN uses.
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D22315
context should share page tables.
Practically it means that dma requests from any device on the bus are
translated according to the entries loaded for the bus:0:0 device.
KPI requires that the slot and function of the device be 0:0, and that
no tags for other devices on the bus were used.
The intended use are NTBs which pass TLPs from the downstream to the
host with slot:func of the downstream originator.
Reviewed and tested by: mav
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D22434
Use the KPI to tweak MSRs in mitigation code.
Reviewed by: markj, scottl
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D22431
This CVE has already been announced in FreeBSD SA-19:26.mcu.
Mitigation for TAA involves either turning off TSX or turning on the
VERW mitigation used for MDS. Some CPUs will also be self-mitigating
for TAA and require no software workaround.
Control knobs are:
machdep.mitigations.taa.enable:
0 - no software mitigation is enabled
1 - attempt to disable TSX
2 - use the VERW mitigation
3 - automatically select the mitigation based on processor
features.
machdep.mitigations.taa.state:
inactive - no mitigation is active/enabled
TSX disable - TSX is disabled in the bare metal CPU as well as
- any virtualized CPUs
VERW - VERW instruction clears CPU buffers
not vulnerable - The CPU has identified itself as not being
vulnerable
Nothing in the base FreeBSD system uses TSX. However, the instructions
are straight-forward to add to custom applications and require no kernel
support, so the mitigation is provided for users with untrusted
applications and tenants.
Reviewed by: emaste, imp, kib, scottph
Sponsored by: Intel
Differential Revision: 22374
Disable the use of executable 2M page mappings in EPT-format page
tables on affected CPUs. For bhyve virtual machines, this effectively
disables all use of superpage mappings on affected CPUs. The
vm.pmap.allow_2m_x_ept sysctl can be set to override the default and
enable mappings on affected CPUs.
Alternate approaches have been suggested, but at present we do not
believe the complexity is warranted for typical bhyve's use cases.
Reviewed by: alc, emaste, markj, scottl
Security: CVE-2018-12207
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D21884
Currently NMIs are sent over event channels, but that defeats the
purpose of NMIs since event channels can be masked. Fix this by
issuing NMIs using a hypercall, which injects a NMI (vector #2) to the
desired vCPU.
Note that NMIs could also be triggered using the emulated local APIC,
but using a hypercall is better from a performance point of view
since it doesn't involve instruction decoding when not using x2APIC
mode.
Reported and Tested by: avg
Sponsored by: Citrix Systems R&D
x86 stack_save_td_running() can work safely only if IPI_TRACE is a
non-maskable interrupt. But at the moment FreeBSD/Xen does not provide
support for the NMI delivery mode. So, mark the functionality as
unsupported similarly to other platforms without NMI.
Maybe there is a way to provide a Xen-specific working
stack_save_td_running(), but I couldn't figure it out.
MFC after: 3 weeks
Sponsored by: Panzura
Enabling interrupts on htt cores has benefits to workloads which are primarily
interrupt driven by increasing the logical cores available for interrupt handling.
The tunable is named machdep.hyperthreading_intr_allowed
Reviewed by: kib, jhb
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D22233
The rationale is pretty much the same as in r353747.
There is no subsequent dependent store.
The store is to the regular (TSO) memory anyway.
MFC after: 23 days
Rather than a few scattered places in the tree. Organize flag names in a
contiguous region of specialreg.h.
While here, delete deprecated PCOMMIT from leaf 7.
No functional change.
The former spelling probably confused MOVDIR64B with MOVDIRI64.
MOVDIR_64B is the 64-*byte* direct store instruction; MOVDIR_I64 is the
64-*bit* direct store instruction (underscores added here for clarity; they are
not part of the canonical instruction name).
No functional change.
Sponsored by: Dell EMC Isilon
ABI already guarantees the direction is forward. Note this does not take care
of i386-specific cld's.
Reviewed by: kib
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D21906
Convert all remaining references to that field to "ref_count" and update
comments accordingly. No functional change intended.
Reviewed by: alc, kib
Sponsored by: Intel, Netflix
Differential Revision: https://reviews.freebsd.org/D21768
leaf 0x15 is not functional.
This should improve automatic TSC frequency determination on
Skylake/Kabylake/... families, where 0x15 exists but does not provide
all necessary information. SDM contains relatively strong wording
against such uses of 0x16, but Intel does not give us any other way to
obtain the frequency. Linux did the same in the commit
604dc9170f2435d27da5039a3efd757dceadc684.
Based on submission by: Neel Chauhan <neel@neelc.org>
PR: 240475
Reviewed by: markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D21777
doing so adds more flexibility with less redundant code.
Reviewed by: jhb, markj, kib
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D21250
Move the floppy driver to the x86 specific notes file.
Reviewed by: jhb, manu, jhibbits, emaste
Differential Revision: https://reviews.freebsd.org/D21208
x86 needs sc, as does sparc64. powerpc doesn't use it by default, but some old
powermac notebooks do not work with vt yet for reasons unknonw. Even so, I've
removed it from powerpc LINT. It's not in daily use there, and the intent is to
100% switch to vt now that it works for that platform to limit support burden.
All the other architectures omit some or all of the screen savers from their
lint config. Move them to the x86 NOTES files and remove the exclusions. This
reduces slightly the number of savers sparc64 compiles, but since they are in
GENERIC, the overage is adequate and if someone reaelly wants to sort them out
in sparc64 they can sweat the details and the testing.
Reviewed by: jhb (earlier version), manu (earlier version), jhibbits
Differential Revision: https://reviews.freebsd.org/D21233
Depending on system configuration, version, and architecture,
mds_handler might be dereferenced from doreti before
hw_mds_recalculate_boot() initialized it. Statically assign void
method to cover all cases.
Reported by: "Schuendehuette, Matthias (LDA IT PLM)" <matthias.schuendehuette@siemens.com>
Sponsored by: The FreeBSD Foundation
MFC after: 3 days
that it becomes increasingly expensive to process a steady stream of
correctable errors. Additionally, the memory used by the MCA entries can
grow without bound.
Change the code to maintain two separate lists: a list of entries which
still need to be logged, and a list of entries which have already been
logged. Additionally, allow a user-configurable limit on the number of
entries which will be saved after they are logged. (The limit defaults
to -1 [unlimited], which is the current behavior.)
Reviewed by: imp, jhb
MFC after: 2 weeks
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D20482
This is needed for AMD SMCA processors, as SMCA uses different
MSR address for access MCA banks.
Use IA32 specific msr_ops as defualt, and use SMCA-specific msr_ops
when on an SMCA-enabled processor
Submitted by: chandu from amd dot com
Reviewed by: cem
Differential Revision: https://reviews.freebsd.org/D18055
If MDS mitigation is enabled by the tunable but MDS microcode is not
early-loaded, software mitigation is selected. This causes
initializecpu() to try to allocate memory which makes boot process
very unhappy.
Create SYSINIT that runs sufficiently late to succeed.
Reported by: naddy
PR: 237968
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
are able to determine some virtual machines, but the vm_guest variable was
still only being set to VM_GUEST_VM.
Since we do know what some of them specifically are, we can set vm_guest
appropriately.
Also, if we see the CPUID has the HV flag, but we were unable to find a
definitive vendor in the Hypervisor CPUID Information Leaf, fall back to
the older detection methods, as they may be able to determine a specific
HV type.
Add VM_GUEST_PARALLELS value to VM_GUEST for Parallels.
Approved by: cem
Differential Revision: https://reviews.freebsd.org/D20305
This allows replacing "sys/eventfilter.h" includes with "sys/_eventfilter.h"
in other header files (e.g., sys/{bus,conf,cpu}.h) and reduces header
pollution substantially.
EVENTHANDLER_DECLARE and EVENTHANDLER_LIST_DECLAREs were moved out of .c
files into appropriate headers (e.g., sys/proc.h, powernv/opal.h).
As a side effect of reduced header pollution, many .c files and headers no
longer contain needed definitions. The remainder of the patch addresses
adding appropriate includes to fix those files.
LOCK_DEBUG and LOCK_FILE_LINE_ARG are moved to sys/_lock.h, as required by
sys/mutex.h since r326106 (but silently protected by header pollution prior
to this change).
No functional change (intended). Of course, any out of tree modules that
relied on header pollution for sys/eventhandler.h, sys/lock.h, or
sys/mutex.h inclusion need to be fixed. __FreeBSD_version has been bumped.
type, use a table to make it easier to add more in the future, if needed.
Add VirtualBox detection to the table ("VBoxVBoxVBox" is the hypervisor
vendor string to look for.) Also add VM_GUEST_VBOX to the VM_GUEST
enumeration to indicate VirtualBox.
Save the CPUID base for the hypervisor entry that we detected. Driver code
may need to know about it in order to obtain additional CPUID features.
Approved by: bryanv, jhb
Differential Revision: https://reviews.freebsd.org/D16305
With lockless DI, pmap_remove() requires operational thread lock,
which is initialized at SI_SUB_RUN_QUEUE for thread0. Move it even
later where APs are started, the moment after which other boot memory
like trampoline stacks is already being freed.
Reported by: gtetlow
Sponsored by: The FreeBSD Foundation
MFC after: 30 days
In all practical situations, the resolver visibility is static.
Requested by: markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Approved by: so (emaste)
Differential revision: https://reviews.freebsd.org/D20281
A static analyzer complained about a couple instances of checking a
variable against NULL after already having dereferenced it.
- dmar_gas_alloc_region: remove the tautological NULL checks
- dmar_release_resources / dmar_fini_fault_log: don't deref unit->regs
unless initialized.
And while here, fix an inverted initialization check in dmar_fini_qi.
Reviewed by: kib
Sponsored by: Dell EMC Isilon
Differential revision: https://reviews.freebsd.org/D20263
Microarchitectural buffers on some Intel processors utilizing
speculative execution may allow a local process to obtain a memory
disclosure. An attacker may be able to read secret data from the
kernel or from a process when executing untrusted code (for example,
in a web browser).
Reference: https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00233.html
Security: CVE-2018-12126, CVE-2018-12127, CVE-2018-12130, CVE-2019-11091
Security: FreeBSD-SA-19:07.mds
Reviewed by: jhb
Tested by: emaste, lwhsu
Approved by: so (gtetlow)
This gets rid of the global cpu_ipi_pending array.
While replace cmpset with fcmpset in the delivery code and opportunistically
check if given IPI is already pending.
Sponsored by: The FreeBSD Foundation
IPI_STOP is used after panic or when ddb is entered manually. MONITOR/
MWAIT allows CPUs that support the feature to sleep in a low power way
instead of spinning. Something similar is already used at idle.
It is perhaps especially useful in oversubscribed VM environments, and is
safe to use even if the panic/ddb thread is not the BSP. (Except in the
presence of MWAIT errata, which are detected automatically on platforms with
known wakeup problems.)
It can be tuned/sysctled with "machdep.stop_mwait," which defaults to 0
(off). This commit also introduces the tunable
"machdep.mwait_cpustop_broken," which defaults to 0, unless the CPU has
known errata, but may be set to "1" in loader.conf to signal that mwait
wakeup is broken on CPUs FreeBSD does not yet know about.
Unfortunately, Bhyve doesn't yet support MONITOR extensions, so this doesn't
help bhyve hypervisors running FreeBSD guests.
Submitted by: Anton Rang <rang AT acm.org> (earlier version)
Reviewed by: kib
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D20135
Rather than just accessing it via pointer cast.
No functional change intended.
Discussed with: kib (earlier version)
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D20135
