Commit Graph

556 Commits

Author SHA1 Message Date
John Baldwin
bc153c692f Add a new bus method to fetch device-specific CPU sets.
bus_get_cpus() returns a specified set of CPUs for a device.  It accepts
an enum for the second parameter that indicates the type of cpuset to
request.  Currently two valus are supported:

 - LOCAL_CPUS (on x86 this returns all the CPUs in the package closest to
   the device when DEVICE_NUMA is enabled)
 - INTR_CPUS (like LOCAL_CPUS but only returns 1 SMT thread for each core)

For systems that do not support NUMA (or if it is not enabled in the kernel
config), LOCAL_CPUS fails with EINVAL.  INTR_CPUS is mapped to 'all_cpus'
by default.  The idea is that INTR_CPUS should always return a valid set.

Device drivers which want to use per-CPU interrupts should start using
INTR_CPUS instead of simply assigning interrupts to all available CPUs.
In the future we may wish to add tunables to control the policy of
INTR_CPUS (e.g. should it be local-only or global, should it ignore
SMT threads or not).

The x86 nexus driver exposes the internal set of interrupt CPUs from the
the x86 interrupt code via INTR_CPUS.

The ACPI bus driver and PCI bridge drivers use _PXM to return a suitable
LOCAL_CPUS set when _PXM exists and DEVICE_NUMA is enabled.  They also and
the global INTR_CPUS set from the nexus driver with the per-domain set from
_PXM to generate a local INTR_CPUS set for child devices.

Reviewed by:	wblock (manpage)
Differential Revision:	https://reviews.freebsd.org/D5519
2016-05-02 18:00:38 +00:00
Roger Pau Monné
f65466eb3a atrtc: export function to set RTC
This is going to be used by the Xen clock on Dom0 in order to set the RTC of
the host. The current logic in atrtc_settime is moved to atrtc_set and the
unused device_t parameter is removed from the atrtc_set function call so it
can be safely used by other callers.

Sponsored by:		Citrix Systems R&D
Reviewed by:		kib, jhb
Differential revision:	https://reviews.freebsd.org/D6067
2016-05-02 16:14:55 +00:00
Pedro F. Giffuni
d9c9c81c08 sys: use our roundup2/rounddown2() macros when param.h is available.
rounddown2 tends to produce longer lines than the original code
and when the code has a high indentation level it was not really
advantageous to do the replacement.

This tries to strike a balance between readability using the macros
and flexibility of having the expressions, so not everything is
converted.
2016-04-21 19:57:40 +00:00
Conrad Meyer
3765b80993 SRAT: Don't overflow domain_pxm table
If we reached MAXMEMDOM, we would previously try to insert an additional
element and only detect overflow after causing (probably trivial) memory
overflow.  Instead, detect the ndomain > MAXMEMDOM case before we write past
the end.

Reported by:	Coverity
CID:		1354783
Sponsored by:	EMC / Isilon Storage Division
2016-04-20 01:10:07 +00:00
Pedro F. Giffuni
ea24b0561f X86: use our nitems() macro when it is avaliable through param.h.
No functional change, only trivial cases are done in this sweep,

Discussed in:	freebsd-current
2016-04-19 23:41:46 +00:00
Konstantin Belousov
e164cafc69 Add hw.dmar.batch_coalesce tunable/sysctl, which specifies rate at
which queued invalidation completion interrupt is requested with
regard to the queued invalidation requests.  In other words, setting
the value of the knob to N requests completion interrupt after N items
are processed.  Existing behaviour is restored by setting
hw.dmar.batch_coalesce=1.

The knob significantly decreases the DMAR qi interrupt rate at the
cost of slightly longer DMAR map entries recycling.

Sponsored by:	The FreeBSD Foundation
2016-04-17 10:56:56 +00:00
Konstantin Belousov
c5c20928d3 Add x86 CPU features definitions published in the Intel SDM rev. 58.
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2016-04-16 06:07:13 +00:00
Konstantin Belousov
9e297f96d4 Always calculate divisor for the counter mode of LAPIC timer. Even if
initially configured in the TSC deadline mode, eventtimer subsystem
can be switched to periodic, and then DCR register is loaded with
unitialized value.

Reset the LAPIC eventtimer frequency and min/max periods when changing
between deadline and counted periodic modes.

Reported and tested by:	Vladimir Zakharov <zakharov.vv@gmail.com>
Sponsored by:	The FreeBSD Foundation
2016-04-15 14:36:38 +00:00
Roger Pau Monné
9b44287ce5 busdma/bounce: revert r292255
Revert r292255 because it can create bounced regions without contiguous
page offsets, which is needed for USB devices.

Another solution would be to force bouncing the full buffer always (even
when only one page requires bouncing), but this seems overly complicated and
unnecessary, and it will probably involve using more bounce pages than the
current code.

Reported by: phk
2016-04-15 09:21:50 +00:00
Pedro F. Giffuni
a3269b0863 x86: for pointers replace 0 with NULL.
These are mostly cosmetical, no functional change.

Found with devel/coccinelle.
2016-04-14 17:04:06 +00:00
Warner Losh
bd3bce41db Deprecate using hints.acpi.0.rsdp to communicate the RSDP to the
system. This uses the hints mechnanism. This mostly works today
because when there's no static hints (the default), this value can be
fetched from the hint. When there is a static hints file, the hint
passed from the boot loader to the kernel is ignored, but for the BIOS
case we're able to find it anyway. However, with UEFI, the fallback
doesn't work, so we get a panic instead.

Switch to acpi.rsdp and use TUNABLE_ULONG_FETCH instead. Continue to
generate the old values to allow for transitions. In addition, fall
back to the old method if the new method isn't present.

Add comments about all this.

Differential Revision: https://reviews.freebsd.org/D5866
2016-04-14 04:59:51 +00:00
Andriy Gapon
0d63fc3ed8 re-enable AMD Topology extension on certain models if disabled by BIOS
Some BIOSes disable AMD Topology extension on AMD Family 15h notebook
processors.  We re-enable the extension, so that we can properly discover
core and cache topology.  Linux seems to do the same.

Reported by:	Johannes Dieterich <dieterich.joh@gmail.com>
Reviewed by:	jhb, kib
Tested by:	Johannes Dieterich <dieterich.joh@gmail.com>
		(earlier version)
MFC after:	3 weeks
Differential Revision:	https://reviews.freebsd.org/D5883
2016-04-12 13:30:39 +00:00
Pedro F. Giffuni
74b8d63dcc Cleanup unnecessary semicolons from the kernel.
Found with devel/coccinelle.
2016-04-10 23:07:00 +00:00
John Baldwin
62d70a8174 Add more fine-grained kernel options for NUMA support.
VM_NUMA_ALLOC is used to enable use of domain-aware memory allocation in
the virtual memory system.  DEVICE_NUMA is used to enable affinity
reporting for devices such as bus_get_domain().

MAXMEMDOM must still be set to a value greater than for any NUMA support
to be effective.  Note that 'cpuset -gd' always works if MAXMEMDOM is
enabled and the system supports NUMA.

Reviewed by:	kib
Differential Revision:	https://reviews.freebsd.org/D5782
2016-04-09 13:58:04 +00:00
Sepherosa Ziehau
19605ff758 xen: Set ipi_{alloc,free} even for UP
This keeps XEN apic_ops aligned w/ x86's.

Suggested by:	kib, jhb
Reviewed by:	jhb, royger
Sponsored by:	Microsoft OSTC
Differential Revision:	https://reviews.freebsd.org/D5871
2016-04-07 07:00:00 +00:00
Sepherosa Ziehau
8b0986c27f x86: Allow interrupt vector allocation/free even on UP
It is needed by the hypervisor FreeBSD guest to allocate/free private
interrupt vectors.

Reviewed by:	kib, jhb, Dexuan Cui <decui microsoft com>
Sponsored by:	Microsoft OSTC
Differential Revision:	https://reviews.freebsd.org/D5849
2016-04-07 06:36:03 +00:00
Andriy Gapon
c77702de74 x86 topo: add some comments, descriptions and references to documentation
Plus a minor cosmetic change.

MFC after:	1 month
2016-04-05 10:36:40 +00:00
Andriy Gapon
4725e6bff3 new x86 smp topology detection code
Previously, the code determined a topology of processing units
(hardware threads, cores, packages) and then deduced a cache topology
using certain assumptions.  The new code builds a topology that
includes both processing units and caches using the information
provided by the hardware.

At the moment, the discovered full topology is used only to creeate
a scheduling topology for SCHED_ULE.
There is no KPI for other kernel uses.

Summary:
- based on APIC ID derivation rules for Intel and AMD CPUs
- can handle non-uniform topologies
- requires homogeneous APIC ID assignment (same bit widths for ID
  components)
- topology for dual-node AMD CPUs may not be optimal
- topology for latest AMD CPU models may not be optimal as the code is
  several years old
- supports only thread/package/core/cache nodes

Todo:
  - AMD dual-node processors
  - latest AMD processors
  - NUMA nodes
  - checking for homogeneity of the APIC ID assignment across packages
  - more flexible cache placement within topology
  - expose topology to userland, e.g., via sysctl nodes

Long term todo:
  - KPI for CPU sharing and affinity with respect to various resources
    (e.g., two logical processors may share the same FPU, etc)

Reviewed by:	mav
Tested by:	mav
MFC after:	1 month
Differential Revision:	https://reviews.freebsd.org/D2728
2016-04-04 16:09:29 +00:00
John Baldwin
2b1e924b69 Move i386/i386/autoconf.c to sys/x86/x86 and use it on both amd64 and i386. 2016-04-03 23:03:54 +00:00
Konstantin Belousov
5c8e0b3bcb Style(9), use tabs for the #define LOOPS line.
Print unsigned values with %u.
Make code slightly more compact by inlining loop limit.

Noted by:	bde
Sponsored by:	The FreeBSD Foundation
2016-04-01 08:47:23 +00:00
Konstantin Belousov
0df87548b9 Type of the interrupt handlers on x86 cannot be expressed in C.
Simplify and unify placeholder type definitions.

Reviewed by:	jhb
Sponsored by:	The FreeBSD Foundation
Differential revision:	https://reviews.freebsd.org/D5771
2016-03-29 19:56:48 +00:00
Konstantin Belousov
d317106ce2 Fix several bugs in r297374:
- fix UP build [1]
- do not obliterate initial reading of rdtsc by the loop counter [2]
- restore the meaning of the argument -1 to native_lapic_ipi_wait()
  as wait until LAPIC acknowledge without timeout
- correct formula for calculating loop iteration count for 1us, it was
  inverted, and ensure that even on unlikely slow CPUs at least one
  check for ack is performed.

Reported by:	Michael Butler <imb@protected-networks.net> [1], rpokala[2],
	jhb[3]
Tested by:	Michael Butler
Pointy hat to:	kib
Sponsored by:	The FreeBSD Foundation
2016-03-29 19:54:13 +00:00
Konstantin Belousov
998e1ef11f Calibrate the frequency of the of the native_lapic_ipi_wait() loop,
and avoid a delay while waiting for IPI delivery acknowledgement in
xAPIC mode.  This makes the loop exit immediately after the delivery
bit in APIC_ICR register is set, instead of waiting for some
microseconds.

We only need to ensure that some amount of time is allowed for the
LAPIC to react to the command, and we need that the wait time is
finite and reasonable.  For that reasons, it is irrelevant if the CPU
frequency or throttling decrease the speed and make the loop,
calibrated for full CPU speed at boot time, execute somewhat slower.

Discussed with:	bde, jhb
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
2016-03-29 08:44:56 +00:00
Konstantin Belousov
d58c003a8a Use ANSI function definition.
Sponsored by:	The FreeBSD Foundation
2016-03-29 08:31:34 +00:00
Konstantin Belousov
841d5e0151 Do not load LAPIC_DCR_TIMER with an undefined value. If we are in the
deadline mode the divide configuration is not used and
lapic_timer_divisor is not set.

Reported by:	dhw, mav
Tested by:	mav
Sponsored by:	The FreeBSD Foundation
2016-03-28 15:05:00 +00:00
Konstantin Belousov
ecabd74728 Use TSC deadline mode for LAPIC timer, when available. The mode fires
LAPIC timer iinterrupt when TSC reaches the value written to the
IA32_TSC_DEADLINE MSR.  To arm or reset the timer in deadline mode, a
single non-serializing MSR write is enough.  This is an advance from
the one-shot mode of LAPIC, where timer operated with the FSB
frequency and required two (serialized in case of xAPIC) writes to the
APIC registers.

The LVT_TIMER register value is cached to avoid unneeded writes in the
deadline mode.  Unused arguments to specify period (which is passed in
struct lapic as la_timer_period) and interrupt enable (which is always
enabled) are removed from lapic_timer_{oneshot,periodic,deadline}
functions.  Instead, special lapic_timer_oneshot_nointr() function for
interrupt-less one-shot calibration is added.

Reviewed by:	mav (previous version)
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
Differential revision:	https://reviews.freebsd.org/D5738
2016-03-28 09:52:44 +00:00
Konstantin Belousov
7c4e76935e Add defines for the LAPIC TSC deadline timer mode. The LVT timer mode
field is two-bit, extend the mask.

Also add comments about all MSRs writes to which are not serializing.

Sponsored by:	The FreeBSD Foundation
2016-03-28 09:43:40 +00:00
John Baldwin
7a2c1d8c60 Enable interrupts on the BSP once all PICs are initialized.
This moves the enabling of interrupts slightly earlier (the old location
was still before devices were enumerated and probed) and does it in the
interrupt code (rather than in the device configuration code).  This
also avoids tripping over an assertion on the first TLB shootdown with
earlier AP startup.

Reviewed by:	kib
Sponsored by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D5710
2016-03-24 00:24:07 +00:00
Justin Hibbits
f8fd3fb518 Fix the resource_list_print_type() calls to use uintmax_t.
Missed a bunch from r297000.
2016-03-22 22:25:08 +00:00
John Baldwin
4a5202f9c4 Check IPI status more frequently when waiting.
An IPI cannot be sent via the local APIC if a previous IPI is still
being delivered.  Attempts to send an IPI will wait for a pending IPI
to clear.  Prior to r278325 these checks used a spin loop with a
hardcoded maximum count which broke AP startup on some systems.
However, r278325 also enforced a minimum latency of 5 microseconds if an
IPI was still pending which resulted in a measurable performance hit.
This change reduces that minimum latency to 1 microsecond.

Tested by:	stas
MFC after:	3 days
2016-03-18 19:48:49 +00:00
Justin Hibbits
da1b038af9 Use uintmax_t (typedef'd to rman_res_t type) for rman ranges.
On some architectures, u_long isn't large enough for resource definitions.
Particularly, powerpc and arm allow 36-bit (or larger) physical addresses, but
type `long' is only 32-bit.  This extends rman's resources to uintmax_t.  With
this change, any resource can feasibly be placed anywhere in physical memory
(within the constraints of the driver).

Why uintmax_t and not something machine dependent, or uint64_t?  Though it's
possible for uintmax_t to grow, it's highly unlikely it will become 128-bit on
32-bit architectures.  64-bit architectures should have plenty of RAM to absorb
the increase on resource sizes if and when this occurs, and the number of
resources on memory-constrained systems should be sufficiently small as to not
pose a drastic overhead.  That being said, uintmax_t was chosen for source
clarity.  If it's specified as uint64_t, all printf()-like calls would either
need casts to uintmax_t, or be littered with PRI*64 macros.  Casts to uintmax_t
aren't horrible, but it would also bake into the API for
resource_list_print_type() either a hidden assumption that entries get cast to
uintmax_t for printing, or these calls would need the PRI*64 macros.  Since
source code is meant to be read more often than written, I chose the clearest
path of simply using uintmax_t.

Tested on a PowerPC p5020-based board, which places all device resources in
0xfxxxxxxxx, and has 8GB RAM.
Regression tested on qemu-system-i386
Regression tested on qemu-system-mips (malta profile)

Tested PAE and devinfo on virtualbox (live CD)

Special thanks to bz for his testing on ARM.

Reviewed By: bz, jhb (previous)
Relnotes:	Yes
Sponsored by:	Alex Perez/Inertial Computing
Differential Revision: https://reviews.freebsd.org/D4544
2016-03-18 01:28:41 +00:00
Justin Hibbits
534ccd7bbf Replace all resource occurrences of '0UL/~0UL' with '0/~0'.
Summary:
The idea behind this is '~0ul' is well-defined, and casting to uintmax_t, on a
32-bit platform, will leave the upper 32 bits as 0.  The maximum range of a
resource is 0xFFF.... (all bits of the full type set).  By dropping the 'ul'
suffix, C type promotion rules apply, and the sign extension of ~0 on 32 bit
platforms gets it to a type-independent 'unsigned max'.

Reviewed By: cem
Sponsored by:	Alex Perez/Inertial Computing
Differential Revision: https://reviews.freebsd.org/D5255
2016-03-03 05:07:35 +00:00
John Baldwin
cbc4d2db75 Remove taskqueue_enqueue_fast().
taskqueue_enqueue() was changed to support both fast and non-fast
taskqueues 10 years ago in r154167.  It has been a compat shim ever
since.  It's time for the compat shim to go.

Submitted by:	Howard Su <howard0su@gmail.com>
Reviewed by:	sephe
Differential Revision:	https://reviews.freebsd.org/D5131
2016-03-01 17:47:32 +00:00
Justin Hibbits
e665eafb25 Correct the memory rman ranges to be to BUS_SPACE_MAXADDR
Summary:
As part of the migration of rman_res_t to be typed to uintmax_t, memory ranges
must be clamped appropriately for the bus, to prevent completely bogus addresses
from being used.

This is extracted from D4544.

Reviewed By: cem
Sponsored by:	Alex Perez/Inertial Computing
Differential Revision: https://reviews.freebsd.org/D5134
2016-03-01 02:59:06 +00:00
Jung-uk Kim
0eda5b3f23 Silence PVS-Studio warning (V595). It can never be NULL here. 2016-02-23 23:57:24 +00:00
Svatopluk Kraus
a1e1814d76 As <machine/pmap.h> is included from <vm/pmap.h>, there is no need to
include it explicitly when <vm/pmap.h> is already included.

Reviewed by:	alc, kib
Differential Revision:	https://reviews.freebsd.org/D5373
2016-02-22 09:02:20 +00:00
Konstantin Belousov
2fe1339ea2 Some BIOSes ACPI bytecode needs to take (sleepable) acpi mutex for
acpi_GetInteger() execution.  Intel DMAR interrupt remapping code
needs to know UID of the HPET to properly route the FSB interrupts
from the HPET, even when interrupt remapping is disabled, and the code
is executed under some non-sleepable mutexes.

Cache HPET UIDs in the device softc at the attach time and provide
lock-less method to get UID, use the method from the dmar hpet
handling code instead of calling GetInteger().

Reported and tested by:	Larry Rosenman <ler@lerctr.org>
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2016-02-20 13:37:04 +00:00
Justin Hibbits
7915adb560 Introduce a RMAN_IS_DEFAULT_RANGE() macro, and use it.
This simplifies checking for default resource range for bus_alloc_resource(),
and improves readability.

This is part of, and related to, the migration of rman_res_t from u_long to
uintmax_t.

Discussed with:	jhb
Suggested by:	marcel
2016-02-20 01:32:58 +00:00
Konstantin Belousov
90edf67ecf POSIX states that #include <signal.h> shall make both mcontext_t and
ucontext_t available.  Our code even has XXX comment about this.

Add a bit of compliance by moving struct __ucontext definition into
sys/_ucontext.h and including it into signal.h and sys/ucontext.h.

Several machine/ucontext.h headers were changed to use namespace-safe
types (like uint64_t->__uint64_t) to not depend on sys/types.h.
struct __stack_t from sys/signal.h is made always visible in private
namespace to satisfy sys/_ucontext.h requirements.

Apparently mips _types.h pollutes global namespace with f_register_t
type definition.  This commit does not try to fix the issue.

PR:	207079
Reported and tested by:	Ting-Wei Lan <lantw44@gmail.com>
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
2016-02-12 07:38:19 +00:00
Justin Hibbits
2dd1bdf183 Convert rman to use rman_res_t instead of u_long
Summary:
Migrate to using the semi-opaque type rman_res_t to specify rman resources.  For
now, this is still compatible with u_long.

This is step one in migrating rman to use uintmax_t for resources instead of
u_long.

Going forward, this could feasibly be used to specify architecture-specific
definitions of resource ranges, rather than baking a specific integer type into
the API.

This change has been broken out to facilitate MFC'ing drivers back to 10 without
breaking ABI.

Reviewed By: jhb
Sponsored by:	Alex Perez/Inertial Computing
Differential Revision: https://reviews.freebsd.org/D5075
2016-01-27 02:23:54 +00:00
Sepherosa Ziehau
69a53a7a3a hyperv: use x86 generic code to do the hypervisor detection
This is first step to move the generic part of HV code into kernel instead
of module, so that it is possible to use hypercall to implement some other
paravirtualization code in the kernel.

Submitted by:		Howard Su <howard0su@gmail.com>
Reviewed by:		royger, delphij, adrian
Approved by:		adrian (mentor)
Sponsored by:		Microsoft OSTC
Differential Revision:	https://reviews.freebsd.org/D3072
2016-01-14 02:50:13 +00:00
Ed Maste
0e42ee5dd8 Move amd64 metadata.h to x86 and share with i386
MFC after:	1 week
2016-01-07 19:47:26 +00:00
Ian Lepore
69dcb7e771 Make the 'env' directive described in config(5) work on all architectures,
providing compiled-in static environment data that is used instead of any
data passed in from a boot loader.

Previously 'env' worked only on i386 and arm xscale systems, because it
required the MD startup code to examine the global envmode variable and
decide whether to use static_env or an environment obtained from the boot
loader, and set the global kern_envp accordingly.  Most startup code wasn't
doing so.  Making things even more complex, some mips startup code uses an
alternate scheme that involves calling init_static_kenv() to pass an empty
buffer and its size, then uses a series of kern_setenv() calls to populate
that buffer.

Now all MD startup code calls init_static_kenv(), and that routine provides
a single point where envmode is checked and the decision is made whether to
use the compiled-in static_kenv or the values provided by the MD code.

The routine also continues to serve its original purpose for mips; if a
non-zero buffer size is passed the routine installs the empty buffer ready
to accept kern_setenv() values.  Now if the size is zero, the provided buffer
full of existing env data is installed.  A NULL pointer can be passed if the
boot loader provides no env data; this allows the static env to be installed
if envmode is set to do so.

Most of the work here is a near-mechanical change to call the init function
instead of directly setting kern_envp.  A notable exception is in xen/pv.c;
that code was originally installing a buffer full of preformatted env data
along with its non-zero size (like mips code does), which would have allowed
kern_setenv() calls to wipe out the preformatted data.  Now it passes a zero
for the size so that the buffer of data it installs is treated as
non-writeable.
2016-01-02 02:53:48 +00:00
Konstantin Belousov
6b247f858e Add standard extended feature bit 6 from the Intel SDM rev. 57, which
indicates that data-pointer in the saved x87 FPU state is only updated
on FPU exceptions.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2015-12-29 22:14:21 +00:00
John Baldwin
9e8d8b4b0c Move shared variables from {amd64,i386}/initcpu.c to x86/identcpu.c.
While here, move the common bits of <machine/cputypes.h> to
<x86/cputypes.h> as well.

Reviewed by:	kib
Differential Revision:	https://reviews.freebsd.org/D4670
2015-12-23 21:41:42 +00:00
Enji Cooper
b59f7a7ad8 Remove redundant declarations in sys/x86/xen which are now handled in other sys/x86
headers

Differential Revision: https://reviews.freebsd.org/D4685
X-MFC with: r291949
Sponsored by: EMC / Isilon Storage Division
2015-12-23 17:43:55 +00:00
Conrad Meyer
986fd63b46 x86: Add CPUID_STDEXT_* macros for CPU feature bits
A follow-up to r292478 and r292488.

Sponsored by:	EMC / Isilon Storage Division
2015-12-21 04:42:58 +00:00
Conrad Meyer
ce43b54ab2 x86: Detect feature flags "AVX512DQ", "AVX512IFMA", "AVX512BW", "AVX512VBMI"
Documented in Intel Architecture Set Extensions Programming Reference
(319433-023).

Sponsored by:	EMC / Isilon Storage Division
2015-12-20 03:34:30 +00:00
Conrad Meyer
f750a7edaa x86: Detect feature flags "CLWB" and "PCOMMIT"
"The availability of CLWB instruction is indicated by the presence of
the CPUID feature flag CLWB (bit 24 of the EBX register)."

CLWB is similar to CLFLUSHOPT, except that it is not required to discard
cacheline contents.

"On processors that supports PCOMMIT, PCOMMIT is enumerated through
CPUID (CPUID.7.0.EBX[22]) only when the feature is enabled by BIOS."

PCOMMIT is used to cause store-to-memory operations to become persistent
(protected from power failure).

Sponsored by:	EMC / Isilon Storage Division
2015-12-19 20:47:15 +00:00
Roger Pau Monné
a7285da666 x86/bounce: try to always completely fill bounce pages
Current code doesn't try to make use of the full page when bouncing because
the size is only expanded to be a multiple of the alignment. Instead try to
always create segments of PAGE_SIZE when using bounce pages.

This allows us to remove the specific casing done for
BUS_DMA_KEEP_PG_OFFSET, since the requirement is to make sure the offsets
into contiguous segments are aligned, and now this is done by default.

Sponsored by:		Citrix Systems R&D
Reviewed by:		hps, kib
Differential revision:	https://reviews.freebsd.org/D4119
2015-12-15 10:07:03 +00:00