as kernel drivers and their dependency onto mmc(4); this allows for
incrementing the mmc(4) module version but also for entire omission
of these bridge declarations for mmccam(4) in a single place, i. e.
in dev/mmc/bridge.h.
comments, marking unused parameters as such, style(9), whitespace,
etc.
o In the mmc(4) bridges and sdhci(4) (bus) front-ends:
- Remove redundant assignments of the default bus_generic_print_child
device method (I've whipped these out of the tree as part of r227843
once, but they keep coming back ...),
- use DEVMETHOD_END,
- use NULL instead of 0 for pointers.
o Trim/adjust includes.
RPi3 cpufreq is more like that on RPi2. Setting arm frequency
above min (say, "sysctl hw.cpufreq.arm_freq=600000001") turns on
turbo mode, and the firmware automatically raises voltage, sets
frequency to max 1200MHz, and throttle when overheat, etc.
Swap if/else parts and use SOC_BCM2835 def so RPi3 can share the
same cpufreq logic as RPi2, instead of falling to that for RPi.
Submitted by: Jia-Shiun Li <jiashiun@gmail.com>
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D9640
Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.
Submitted by: Jan Schaumann <jschauma@stevens.edu>
Pull Request: https://github.com/freebsd/freebsd/pull/96
This adds clocks support for the aw_ccung on the A31 SoC.
Newer DTS files require this.
All the clocks except two CSI are defined and exported on the clock domain.
The PLL_DDR clock have an update bit which need to be set after changing
the value, add the possibility to define one for NKMP clocks.
This allow us to add the missing clocks.
We now have the full list of clocks created under the clock domain.
This is required for FDT's standard "reg-io-width" property
(similar to "reg-shift" property) found in many DTS files.
This fixes operation on Altera Arria 10 SOC Development Kit,
where standard ns8250 uart allows 4-byte access only.
Reviewed by: kan, marcel
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D9785
Since Linux 4.9-4.10 DTS doesn't have clocks under /clocks but only a ccu node.
Currently only H3 is supported with almost the same state as HEAD.
(video pll aren't supported for now but we don't support video).
This driver and clocks will also be used for other SoC (A64, A31, H5, H2 etc ...)
Reviewed by: jmcneill
Differential Revision: https://reviews.freebsd.org/D9517
Convert PCIe hot plug support over to asking the firmware, if any, for
permission to use the HotPlug hardware. Implement pci_request_feature
for ACPI. All other host pci connections to allowing all valid feature
requests.
Sponsored by: Netflix
if the fdt data doesn't provide a gpio pin for reading the write protect
switch and also doesn't contain a "wp-disable" property.
In r311735 the long-bitrotted code in this driver for using the non-
standard fdt "mmchs-wp-gpio-pin" property was replaced with new common
support code for handling write-protect and card-detect gpio pins. The
old code never found a property with that name, and the logic was to
assume that no gpio pin meant that the card was not write protected.
The new common code behaves differently. If there is no fdt data saying
what to do about sensing write protect, the value in the standard SDHCI
PRESENT_STATE register is used. On this hardware, if there is no signal
for write protect muxed into the sd controller then that bit in the
register indicates write protect.
The real problem here is the fdt data, which should contain "wp-disable"
properties for eMMC and micro-sd slots where write protect is not even
an option in the hardware, but we are not in control of that data, it
comes from linux. So we have to make the same flawed assumption in our
driver that the corresponding linux driver has: no info means no protect.
Reported by: several users on the arm@ list
Pointy hat: me, for not testing enough before committing r311735
This enables the PHY circuitry for UTMI+ level 2 and 3, and sets the
flag to tell the ehci code that the root hub has a transaction translator
in it. For imx6 we can use the standard ehci_get_port_speed_portsc()
function to find out what speed device is connected to the port.
On arm64 use atomics. Then, both arm and arm64 do not need a critical
section around update. Replace all cpus loop by CPU_FOREACH().
This brings arm and arm64 counter(9) implementation closer to current
amd64, but being more RISC-y, arm* version cannot avoid atomics.
Reported by: Alexandre Martins <alexandre.martins@stormshield.eu>
Reviewed by: andrew
Tested by: Alexandre Martins, andrew
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
identify_arm_cpu() in sys/arm/arm/identcpu-v4.c incorrectly uses a
u_int8_t variable to store the result of cpu_get_control().
It should really use a u_int variable, the same way as done for cpu_ident()
in the same function, as both cpuid and control registers are 32-bit..
This issue causes users of identcpu-v4 to incorrectly report things such as
icache status (bit 12 in cpu control register) and basically anything
defined in bits above bit 7 :-)
Reviewed by: manu
Sponsored by: Smartcom - Bulgaria AD
Differential Revision: https://reviews.freebsd.org/D9460
The types are for the byte offset and page index in vm object. They
are similar to off_t, which is defined as 64bit MI integer. Using MI
definitions will allow to provide consistent MD values of vm
object-related maximum sizes.
Reviewed by: alc
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
- Use new option SMP_ON_UP instead of (mis)using specific CPU type.
By this, any SMP kernel can be compiled with SMP_ON_UP support.
- Enable runtime detection of CPU multiprocessor extensions only
if SMP_ON_UP option is used. In other cases (pure SMP or UP),
statically compile only required variant.
- Don't leak multiprocessor instructions to UP kernel.
- Correctly handle data cache write back to point of unification.
DCCMVAU is supported on all armv7 cpus.
- For SMP_ON_UP kernels, detect proper TTB flags on runtime.
Differential Revision: https://reviews.freebsd.org/D9133
Historically AM335x LCDC driver used non-standard "hdmi" property to
refer to HDMI framer. There is no such thing in upstream DTS, so to
handle both cases fallback to bindings described in
bindings/media/video-interfaces.txt in Linux documentation.
We still make some assumptions that are not universally true: we
assume that if remote endpoint is available it's going to be HDMI
framer. Which is true for AM335x-based devices currently supported
but may be not true for some custom hardware.
MFC after: 1 week
register, in addition to configuring it as input with the pinmux driver.
There was a control register bit commented as "no desc in datasheet". A
later revision of the manual reveals the bit to be an input/output control
for the timer pin. In addition to configuring capture or pulse mode, you
apparently have to separately configure the pin direction in the timer
control register.
Before this change, the timer block was apparently driving a signal onto a
pad configured by pinmux as input. Capture mode still accidentally worked
for me during testing because I was using a very strong signal source that
just out-muscled the weaker drive from the misconfigured pin.
Commit r312747 ("Setup decoding windows for ARMADA38X") resulted
in build failing for Marvell platforms, which don't have AHCI controller.
This patch provides a fix by adding dummy functions for such cases.
On the occasion rename register dump routine to decode_win_ahci_dump,
in order to avoid confusion.
Submitted by: Marcin Wojtas <mw@semihalf.com>
Obtained from: Semihalf
Sponsored by: Stormshield
- Replace pcpu_find(curcpu) with get_pcpu(), which is much
more direct.
- Remove armv4 pcpu fields which I added in r286296 but never
needed to use.
- armv6 pc_qmap_addr was leftover from the old armv6 pmap
implementation. Rename it and put it to use in the new one.
Noted by: skra
Reviewed by: skra
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D9312
This file provides support for AHCI mode on Armada38x
and adds new optional AHCI device to arm/mv/files.mv.
Submitted by: Konrad Adamczyk <ka@semihalf.com>
Obtained from: Semihalf
Sponsored by: Stormshield
Reviewed by: zbb
Differential revision: https://reviews.freebsd.org/D9222
It is necesarry to open memory windows on internal bus for
AHCI driver to work correctly.
Submitted by: Konrad Adamczyk <ka@semihalf.com>
Obtained from: Semihalf
Sponsored by: Stormshield
Reviewed by: zbb
Differential revision: https://reviews.freebsd.org/D9220
Configure decoding windows only for devices with
enabled nodes in FDT.
Submitted by: Konrad Adamczyk <ka@semihalf.com>
Obtained from: Semihalf
Sponsored by: Stormshield
Reviewed by: zbb
Differential revision: https://reviews.freebsd.org/D9219
* Currently supports only Armada38X family but other Marvell SoC's
can be added if needed.
* Provides temperature is C deg.
* To print the temperature one can use:
sysctl dev.armada_thermal.0.temperature
Submitted by: Zbigniew Bodek <zbb@semihalf.com>
Obtained from: Semihalf
Sponsored by: Stormshield
Differential revision: https://reviews.freebsd.org/D9217
mappings for armv6 pmap zero and copy operations to the MD PCPU region.
Change sysmap initialization to only allocate KVA pages for CPUs that
are actually present.
While here, collapse CMAP3 into CMAP2 (their use was mutually exclusive
anyway) and "recover" some space in PCPU padding that has always been
available due to 64-byte cacheline padding.
Reviewed by: skra
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D9172
descriptor state will not change anymore). This seems to eliminate the
race where we can miss a stalled queue under high load.
While here remove the unnecessary curly brackets.
Reported by: Konstantin Kormashev <konstantin@netgate.com>
MFC after: 3 days
Sponsored by: Rubicon Communications, LLC (Netgate)
- Pad small packets to 60 bytes and not 64 (exclude the CRC bytes);
- Pad the packet using m_append(9), if the packet has enough space for
padding, which is usually true, it will not be necessary append a newly
allocated mbuf to the chain.
Suggested by: yongari
MFC after: 3 days
Sponsored by: Rubicon Communications, LLC (Netgate)
disabled (Hi netmap!).
Only remove the CRC bytes from packets when the hardware tell us to do so.
Fixes the 'discard frame w/o leading ethernet header' issues.
Sponsored by: Rubicon Communications, LLC (Netgate)
The Zedboard has a hardware bug where initialization of the USB PHY
occasionally fails on boot-up. Fix regression in -CURRENT when
kernel panics on such occasion. 11-RELEASE branch works fine
PR: 215862
Submitted by: Thomas Skibo <thoma555-bsd@yahoo.com>
it into pmap-v4.h where they are used. Other than those few lines of
support for different MMU types, nothing in cpuconf.h has been used in our
code for quite a while.
The file existed to set up a variety of symbols to describe the
architecture. Over the past few years we have converted all of our source
to use the new architecture symbols standardized by ARM Inc, and predefined
by both clang and gcc.
PR: 216104
Replace archaic "busses" with modern form "buses."
Intentionally excluded:
* Old/random drivers I didn't recognize
* Old hardware in general
* Use of "busses" in code as identifiers
No functional change.
http://grammarist.com/spelling/buses-busses/
PR: 216099
Reported by: bltsrc at mail.ru
Sponsored by: Dell EMC Isilon
Add basic support for A33/R16 that is enough to boot a kernel.
This adds the platform code, padconf data and the new clocks strings.
MFC after: 2 weeks
QEMU does not implement hardware debug registers so when
dbg_monitor_is_enabled is called kernel receives "invalid instruction"
exception. QEMU implements only DIDR register and on read returns all
zeroes to indicate that it doesn't support other registers. Real
hardware has Version bits set.
MFC after: 1 week
Rework general approach to locking and working with audio worker thread:
- Use flags to signal requested worker action
- Fix submitted buffer calculations to avoid samples starvation
- Protect buffer pointers with locks to fix race condition between callback
and audio worker thread
- Remove unnecessary vchi_service_use
- Do not use lock to serialize VCHI requests since only one thread issues them now
- Fix unloading signaling per hselasky@ suggestion
- Add output to detect inconsistent callback data caused by possible firmware bug
https://github.com/raspberrypi/firmware/issues/696
- Add stats/debug sysctls to troubleshoot possible bugs
PR: 213687, 205979, 215194
MFC after: 1 week
and host1x module. Unfortunately, tegra124 SoC doesn't have 2D acceleration
engine and 3D requires not yet started nouveau driver.
These drivers forms a first non-x86 DRM2 enabled graphic stack.
Note, there are 2 outstanding issues:
- The code uses gross hack in order to be comply with
OBJT_MGTDEVICE pager. (See tegra_bo_init_pager() in tegra_bo.c)
- Due to improper(probably) refcounting in drm_gem_mmap_single()
(in drm_gem.c), the gem objects are never released.
I hope that I will be able to address both issues in finite time,
but I don't want to touch x86 world now.
MFC after: 1 month
- Place const modifiers where required
- Make sure sdma device is attahched before consumers like SSI
Reviewed by: br
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D8874
file and add a generic DT binding that takes advantage of the extres
framework for setting up clocks.
Reviewed by: gonzo
Differential Revision: https://reviews.freebsd.org/D8826
As cs is stored in a uint32_t, use the last bit to store the
active high flag as it's unlikely that we will have that much CS.
Reviewed by: loos
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D8614
In case where GICD_CTLR.DS is 1, the IGROUPR registers are RW in
non-secure state and has to be initialized to 1 for the
corresponding interrupts to be delivered as Group 1 interrupts.
Update gic_v3_dist_init() and gic_v3_redist_init() to initialize
GICD_IGROUPRn and GICR_IGROUPRn respectively to address this. The
registers can be set unconditionally since the writes are ignored
in non-secure state when GICD_CTLR.DS is 0.
This fixes the hang on boot seen when running qemu-system-aarch64
with machine virt,gic-version=3
Replace them with a default handler that returns devmap_lastaddr.
Reviewed by: mmel
Sponsored by: ABT Systems Ltd
Differential Revision: https://reviews.freebsd.org/D8806
Up until r295436 GPT timer in i.MX6 Dual dts used the same compatiblity
string as i.MX6 Quad. After the sync up with Linux in r295436, GPT timer
stopped getting attached on the i.MX6 Dual
MFC after: 3 days
r309616 changed the definition of GICD_ITARGETSR(n) to take the irq
id as argument, but the usage of the macro in gic_cpu_mask() was not
updated to reflect this. This causes the cpu mask to be computed
incorrectly.
Update the GICD_ITARGETSR() call to fix this, this fixes a hang seen
while booting freebsd on qemu-system-aarch64 with SMP enabled.
Changes include modifications in kernel crash dump routines, dumpon(8) and
savecore(8). A new tool called decryptcore(8) was added.
A new DIOCSKERNELDUMP I/O control was added to send a kernel crash dump
configuration in the diocskerneldump_arg structure to the kernel.
The old DIOCSKERNELDUMP I/O control was renamed to DIOCSKERNELDUMP_FREEBSD11 for
backward ABI compatibility.
dumpon(8) generates an one-time random symmetric key and encrypts it using
an RSA public key in capability mode. Currently only AES-256-CBC is supported
but EKCD was designed to implement support for other algorithms in the future.
The public key is chosen using the -k flag. The dumpon rc(8) script can do this
automatically during startup using the dumppubkey rc.conf(5) variable. Once the
keys are calculated dumpon sends them to the kernel via DIOCSKERNELDUMP I/O
control.
When the kernel receives the DIOCSKERNELDUMP I/O control it generates a random
IV and sets up the key schedule for the specified algorithm. Each time the
kernel tries to write a crash dump to the dump device, the IV is replaced by
a SHA-256 hash of the previous value. This is intended to make a possible
differential cryptanalysis harder since it is possible to write multiple crash
dumps without reboot by repeating the following commands:
# sysctl debug.kdb.enter=1
db> call doadump(0)
db> continue
# savecore
A kernel dump key consists of an algorithm identifier, an IV and an encrypted
symmetric key. The kernel dump key size is included in a kernel dump header.
The size is an unsigned 32-bit integer and it is aligned to a block size.
The header structure has 512 bytes to match the block size so it was required to
make a panic string 4 bytes shorter to add a new field to the header structure.
If the kernel dump key size in the header is nonzero it is assumed that the
kernel dump key is placed after the first header on the dump device and the core
dump is encrypted.
Separate functions were implemented to write the kernel dump header and the
kernel dump key as they need to be unencrypted. The dump_write function encrypts
data if the kernel was compiled with the EKCD option. Encrypted kernel textdumps
are not supported due to the way they are constructed which makes it impossible
to use the CBC mode for encryption. It should be also noted that textdumps don't
contain sensitive data by design as a user decides what information should be
dumped.
savecore(8) writes the kernel dump key to a key.# file if its size in the header
is nonzero. # is the number of the current core dump.
decryptcore(8) decrypts the core dump using a private RSA key and the kernel
dump key. This is performed by a child process in capability mode.
If the decryption was not successful the parent process removes a partially
decrypted core dump.
Description on how to encrypt crash dumps was added to the decryptcore(8),
dumpon(8), rc.conf(5) and savecore(8) manual pages.
EKCD was tested on amd64 using bhyve and i386, mipsel and sparc64 using QEMU.
The feature still has to be tested on arm and arm64 as it wasn't possible to run
FreeBSD due to the problems with QEMU emulation and lack of hardware.
Designed by: def, pjd
Reviewed by: cem, oshogbo, pjd
Partial review: delphij, emaste, jhb, kib
Approved by: pjd (mentor)
Differential Revision: https://reviews.freebsd.org/D4712
will be used by the gicv2m and ITS ACPI drivers to only attach to the
correct parent.
Obtained from: ABT Systems Ltd
Sponsored by: The FreeBSD Foundation
- EMC clock have standard peripheral clock block. Use it.
- Implement full frequency set method for PLLD2. This PLL
is used as HDMI pixel clock so we must be able to set it
to wide range of frequencies, within 5% tolerance allowed
by HDMI specification. Due to this, full state space search
(over m, n, p fields) is necessary.
MFC after: 3 weeks
This function is referenced, but never called from DRM2 code. Also,
real behavior of pmap_mapdev_attr() in ARM world is unclear as we don't
have any additional attribute for a device memory type.
MFC after: 2 weeks
miibus_writereg.
Reduce the DELAY() between reads while waiting for MII access.
Spotted by: yongari
Sponsored by: Rubicon Communications, LLC (Netgate)
Writing the full queue size to it every time was makeing it overflow with a
lot of bogus values.
This fixes the interrupt storms on irq 40.
Sponsored by: Rubicon Communications, LLC (Netgate)
This allows the driver to be built in a kernel with no FDT support, e.g.
on arm64 with just ACPI.
Obtained from: ABT Systems Ltd
Sponsored by: The FreeBSD Foundation
can be selected for it. If the desired frequency is one of those two, use
this mode instead of the integer one.
When calculating the PLL3 freq for the dotclock, check if it is a multiple
of the fracional frequencies.
MFC after: 2 weeks
Adds VLAN and port management abilities for etherswitchcfg(8).
The code is conditionally enabled for now, because it is not necessary on
single ethernet use cases.
Obtained from: pfSense
MFC after: 2 weeks
Sponsored by: Rubicon Communications, LLC (Netgate)
FDT attachment to a new file. A separate ACPI attachment will then be added
to allow arm64 servers with ACPI to use it over FDT.
This should also help with merging this with the ofwpci driver, with
further work needed to remove restrictions this driver places on resource
allocation.
Obtained from: ABT Systems Ltd
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D7319
Use "ti,am33xx" instead of "ti,am335x", which gives an exact match in every
DTS we support.
This fixes the boot on TI SoCs after r308533.
Suggested by: gonzo
Sponsored by: Rubicon Communications, LLC (Netgate)
the aintc driver for Allwinner A10.
This fixes the boot of the GENERIC ARM kernel on TI/AM335x SoCs.
Sponsored by: Rubicon Communications, LLC (Netgate)
While here:
- remove 'device mii' - included by miibus;
- remove 'device smcphy' - included by miibus;
- sorted the network drivers list;
- added a comment about miibus based on amd64/GENERIC.
Sponsored by: Rubicon Communications, LLC (Netgate)
under first_page cannot be taken as this variable is connected only to
vm_page_array segment. There could be more segments in system like
the ones for various fictitious page ranges. These can be situated
under vm_page_array segment and so, they could be skipped before this
fix. However, as far as I know, there is no report associated with it.
While here, the return type of this function is changed from boolean_t
to bool type.
Reviewed by: kib
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D8502
- Move all VCHI activity to worker thread: channel methods are called with
non-sleepable lock held and VCHI uses sleepable lock.
- In worker thread use sx(9) lock instead of mutex(9) for the same reason.
PR: 213801, 205979
machine/armreg.h requires access to the __ARM_ARCH macro, which is not
always properly defined (especially by gcc 4.2.1). We should include
sys/cdefs.h in order to get the definitions in machine/acle-compat.h,
which would properly define the __ARM_ARCH macro in these cases.
So, in cases where machine/armreg.h is included without _SYS_CDEFS_H_
being defined - generate an #error.
Reviewed by: andrew
Sponsored by: Smartcom - Bulgaria AD
Differential Revision: https://reviews.freebsd.org/D8460
Only include sys/boot.h if LINUX_BOOT_ABI is defined in
sys/arm/arm/machdep.c
Not doing this prevents kernels that do not define LINUX_BOOT_ABI from
being build with gcc (at least 4.2.1).
Reviewed by: mmel
Sponsored by: Smartcom - Bulgaria AD
Differential Revision: https://reviews.freebsd.org/D8459
The audio controller in the H3 is more or less the same as A10/A20 except
some registers are shuffled around. The mixer interface, however, is
completely different between SoCs. Separate a10_mixer_class and
h3_mixer_class implementations are now made available. This will also make
adding support for other SoCs easier in the future.
Reviewed by: andrew, ganbold
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D8425
* Rename ARM_HAVE_MP_EXTENSIONS to ARM_USE_MP_EXTENSIONS and extend it to
handle more cases, including when SMP is not enabled.
* Check ARM_USE_MP_EXTENSIONS when building for ARMv7+, even if no SMP.
* Use ARM_USE_MP_EXTENSIONS in pmap-v6.c to detect when to set PRRR_NS1.
With this we should be able to boot on all ARMv7+ Cortex-A cores with
32-bit support.
Reviewed by: mmel, imp (earlier version)
Relnotes: yes
Sponsored by: ABT Systems Ltd
Differential Revision: https://reviews.freebsd.org/D8335
PLL1 is used by the cpu core, allowing changing freq is needed for cpufreq.
The factors table contains all the frequencies in the operating point table
present in the DTS.
MFC after: 1 week
hardware that supports the mp extensions. If so it should use the broadcast
tlb invalidate instructions as other CPUs or devices may need to know about
the invalidation.
To simplify the code have the compiler optimise out the else case when not
builing for Cortex-A8.
Sponsored by: ABT Systems Ltd
Differential Revision: https://reviews.freebsd.org/D8092
Push-Pull Two Wire interface is a almost compatible iic like bus used
in sun6i SoC. It's only use is to communicate with the power management IC.
Reviewed by: jmcneill
MFC after: 1 week
Relnotes: yes
prevent overheating.
When sensor 0's alarm interrupt is fired, set a throttle flag. Further
requests to set CPU frequency will be rejected until sensor 0's temperature
returns to a level below the hot temperature threshold.
Relnotes: yes
The exported functions will be used by
Alpine Ethernet driver.
Obtained from: Semihalf
Submitted by: Michal Stanek <mst@semihalf.com>
Sponsored by: Annapurna Labs
Reviewed by: wma
Differential Revision: https://reviews.freebsd.org/D7763
This patch adds support for MSI-X interrupts
on Annapurna Alpine platform. MSI-X on Alpine
work similarly to GICv2m, i.e. some range of
SPI interrupts is reserved in GIC and individual
SPIs can be triggered by MSI-X messages.
This SPI range is defined in FDT.
Obtained from: Semihalf
Submitted by: Michal Stanek <mst@semihalf.com>
Sponsored by: Annapurna Labs
Reviewed by: nwhitehorn, wma
Differential Revision: https://reviews.freebsd.org/D7579
When detaching device trees parent devices must be detached prior to
detaching its children. This is because parent devices can have
pointers to the child devices in their softcs which are not
invalidated by device_delete_child(). This can cause use after free
issues and panic().
Device drivers implementing trees, must ensure its detach function
detaches or deletes all its children before returning.
While at it remove now redundant device_detach() calls before
device_delete_child() and device_delete_children(), mostly in
the USB controller drivers.
Tested by: Jan Henrik Sylvester <me@janh.de>
Reviewed by: jhb
Differential Revision: https://reviews.freebsd.org/D8070
MFC after: 2 weeks
