Since ath9k does some slightly different bit fiddling when setting up
the TX queues, it may that the TX queue setup/reset functions will need
overriding later on.
This does a few things in particular:
* Abstracts out the gain control settings into a separate function;
* Configure antenna diversity, LNA and antenna gain parameters;
* Configure ob/db entries - the later v4k EEPROM modal revisions have
multiple OB/DB parameters which are used for some form of
calibration. Although the radio does have defaults for each,
the EEPROM can override them.
This resolves the AR2427 related issues I've been seeing and makes
it stable at all 11g rates for both TX and RX.
The offsets didn't match the assumption that nfarray[] is ordered by the
chainmask bits and programmed via the register order in ar5416_cca_regs[].
This repairs that damage and ensures that chain 1 is programmed correctly.
(And extension channels will now be programmed correctly also.)
This fixes some of the stuck beacons I've been seeing on my AR9160/AR5416
setups - because Chain 1 would be programmed -80 or -85 dBm, which is
higher than the actual noise floor and thus convincing the radio that
indeed it can't ever transmit.
rather than duplicating them for the v14 (ar5416+) and v4k (ar9285) codebases.
Further chipsets (eg the AR9287) have yet another EEPROM format which will use
these routines to calculate things.
to the TX closed-loop power control registers.
* Modify a couple of functions to take the register chain number,
rather than the regChainOffset value. This allows for the
register chain to be logged.
Linux ath9k.
The ath9k ar9002_hw_init_cal() isn't entirely clear about what
is supposed to be called for what chipsets, so I'm ignoring the
rest of it and just porting the AR9285 init cal path as-is and
leaving the rest alone. Subsequent commits may also tidy up the
Merlin (AR9285) and other chipset support.
Obtained from: Linux ath9k
The ath9k driver has a unified boundary/pdadc function, whereas
ours is split into two (one for each EEPROM type.) This is why
the AR9280 check is done here where we could safely assume it'll
always be AR9280 or later.
this is incorrect for Kite (AR9285) and any future chipsets that
override the EEPROM related routines.
It meant that a direct call to set the TX power would call the v14 EEPROM
AR5416/AR9280 calibration routines, rather than the v4k EEPROM routines
for the AR9285. It thus read the incorrect values from the EEPROM and
programmed garbage PDADC and TX power values into the hardware.
It looks like these apply in both open and closed loop TX power control,
but the only merlin boards i have either have OL -or- a non-default power
offset, not both.
to both make things clearer, and to make it easier to write userland
code which pulls in these definitions without needing to pull in the
rest of the HAL.
This stuff should be deprecated at some point in the future once
the net80211 regulatory domain support encapsulates all of the
defintions here.
This is something bus clock related from what I can gather. It is needed for
the AR9220 based Ubiquiti SR71-12 and SR71-15 Mini-PCI NICs.
(Note: those NICs don't work right now because of earlier changes to handle
power table offset correctly. That'll be resolved in a follow-up commit.)
Merlin (ar9280) and later were full-reset if they're doing open-loop TX
power control but the TSF wasn't being saved/restored.
Add ar5212SetTsf64() which sets the 64 bit TSF appropriately.
generally tidy up the TX power programming code.
Enforce that the TX power offset for Merlin is -5 dBm, rather than
any other value programmable in the EEPROM. This requires some
further code to be ported over from ath9k, so until that is done
and tested, fail to attach NICs whose TX power offset isn't -5
dBm.
This improves both legacy and HT transmission on my merlin board.
It allows for stable MCS TX up to MCS15.
Specifics:
* Refactor out a bunch of the TX power calibration code -
setting/obtaining the power detector / gain boundaries,
programming the PDADC
* Take the -5 dBm TX power offset into account on Merlin -
"0" in the per-rate TX power register means -5 dBm, not
0 dBm
* When doing OLC
* Enforce min (0) and max (AR5416_MAX_RATE_POWER) when fiddling
with the TX power, to avoid the TX power values from wrapping
when low.
* Implement the 1 dBm cck power offset when doing OLC
* Implement temperature compensation for 2.4ghz mode when doing OLC
* Implement an AR9280 specific TX power calibration routine which
includes the OLC twiddles, leaving the earlier chipset path
(AR5416, AR9160) alone
Whilst here, use these refactored routines for the AR9285 TX power
calibration/programming code and enforce correct overflow/underflow
handling when fiddling with TX power values.
Obtained from: linux ath9k
It defaults to -5 dBm for eeproms earlier than v21.
This apparently only applies to Merlin (AR9280) or later,
earlier 11n chipsets have a power table offset of 0.
All the code in ath9k which checks the power table offset
and takes it into account first ensures the chip is
Merlin or later.
The earlier way of doing debugging would evaluate the function parameters
before calling the HALDEBUG. In the case of detailed register debugging
would mean a -lot- of unneeded register IO and other stuff was going on.
This method evaluates the ath_hal_debug variable before the function
parameters are evaluated, drastically reducing the amount of overhead
enabling HAL debugging during compilation.
determining whether to use MRR or not.
It uses the 11g protection mode when calculating 11n related stuff, rather
than checking the 11n protection mode.
Furthermore, the 11n chipsets can quite happily handle multi-rate retry w/
protection; the TX path and rate control modules need to be taught about
that.
* change the BB gating logic to explicitly define which chips are covered;
the ath9k method isn't as clear.
* don't disable the BB gating for now, the ar5416 initvals have it, and the
ar9160 initval sets it to 0x0. Figure out why before re-enabling this.
* migrate the Merlin (ar9280) applicable WAR from the Kite (ar9285) code
(which won't get called for Merlin!) and stuff it in here.
* add dot11rate_label() which returns Mb or MCS based on legacy or HT
* use it everywhere dot11rate() is used
* in the "current selection" part at the top of the debugging output,
otuput what the rate itself is rather than the rix. The rate index
(rix) has very little meaning to normal humans who don't know how
to find the PHY settings for each of the chipsets; pointing out the
rix rate and type is likely more useful.
These flags are just plain wrong - they're the node flags from negotiation,
not the configured flags. I'll jump in later on and figure out exactly
what should be done to properly set these two flags when in both STA mode
(ie, what the AP says is possible and what's configured) and AP mode
(ie, where the AP has a configuration, but then negotiates what's possible
with each node, so per-node configuration can and will differ.)
This allows the 11n 2.4ghz/ht20 mode to associate (but perform poorly still)
and exchange MCS rates with atheros reference APs and a Cisco/Linksys
E3000 AP.
* Turn ath_tx_calc_ctsduration() into a function that
returns the ctsduration, or -1 for HT rates;
* add a printf() to ath_tx_calc_ctsduration() which will be
very loud if somehow that function is called with an MCS
rate;
* Add ath_tx_get_rtscts_rate() which returns the RTS/CTS
rate to use for the given data rate, incl. the short
preamble flag;
* Only call ath_tx_calc_ctsduration() for non-11n chipsets;
11n chipsets don't require the rtscts duration to be
calculated.
It's used to calculate:
* the initial per-rate entries for short/long preamble ACK durations;
* packet durations for TDMA slot decisions;
* RTS/CTS protection durations;
* updating the duration field in the 802.11 frame header
This way invalid durations will generate a warning, prompting for it to be
fixed.
as they're likely not entirely correct, but they give people something
to toy with to compare behaviour/performance.
Disable the anti-noise part, as this apparently interferes with
RIFS. I haven't verified this.
packet duration for the ath_rate_sample module.
This doesn't affect the packet TX at all; only how much time the
sample rate module attributes to a completed TX.
correctly:
* pass in whether to allow the hardware to override the duration field
in the main data frame (durupdate_en) - PS_POLL frames in particular
don't have the duration bit overriden;
* there's no rts/cts duration here; that's done elsehwere
There's still a lot of random issues to sort out with the radio side of
things and AMPDU RX handling (and completely missing AMPDU TX handling!)
but if people wish to give this a go and assist in debugging the
issues, they can define ATH_DO_11N to enable it.
I'm just re-iterating - this is here to allow people to assist in
further 11n development; it is not any indication that the 11n support
is complete and functional.
Important notes:
* This doesn't support 1-stream cards yet - (eg AR9285) - the various bits
that negotiate TX/RX MCS don't know not to try >1 stream TX or negotiate
1-stream RX; so don't enable 11n unless you've first taught the rate
control module and the net80211 stack to negotiate 1-stream stuff;
* The only rate control module minimally 11n aware is ath_rate_sample;
* ath_rate_sample doesn't know about HT/40; so airtime will be incorrectly
calculated;
* The AR9160 and AR9280 radio code is unreliable at the higher MCS rates for
some reason; this will definitely impact 11n performance;
* AMPDU-TX isn't yet implemented;
* AMPDU-RX may be a bit buggy still and will definitely suffer from the
radio unreliability mentioned above (ie, don't expect 150/300mbit
RX just yet.)
The correct bit to set is 0x1 in the high MAC address byte, not 0x80.
The hardware isn't programmed with that bit (which is the multicast
adress bit.)
The linux ath9k keycache code uses that bit in the MAC as a "this is
a multicast key!" and doesn't set the AR_KEYTABLE_VALID bit.
This tells the hardware the MAC isn't to be used for unicast destination
matching but it can be used for multicast bssid traffic.
This fixes some encryption problems in station mode.
PR: kern/154598
Revert back to the previous method of doing it for where a node can be
identified and it's an 11n node.
I'll have to do some further research into exactly what is being messed up
with the sequence number matching and I'll then revisit this.
This doesn't yet take into account HT40 packet durations as the node info
(needed to know if it's a HT20 or HT40 node) isn't available everywhere
it needs to be.
putting descriptors (not buffers) across a 4k page boundary can cause issues.
I've not seen it in production myself but it apparently can cause problems.
So, in preparation for addressing this workaround, (re)-expose the particular
HAL capability bit which marks whether the chipset has support for cross-4k-
boundary transactions or not.
A subsequent commit will modify the descriptor allocation to avoid allocating
descriptor entries that straddle a 4k page boundary.
* The existing radio config code was for the AR5416/AR9160 and missed out
on some of the AR9280 specific stuff. Include said stuff from ath9k.
* Refactor out the gain control settings into a new function, again pilfered
from ath9k.
* Use the analog register RMW macro when touching analog registers.
Obtained from: Linux ath9k
This fixes two problems -
* All packets need to be processed here, not just aggregate ones - as any
received frames (AMPDU or otherwise) in the given TID (traffic class id)
will update the sequence number and, implied with that, update the window;
* It seems there's situations where packets aren't matching a current node but
somehow need to be tracked. Thus just tag them all for now; I'll figure out
the why later.
Whilst I'm here, bump the stats counters whilst I'm at it.
This fixes AMPDU RX in my tests; the main problems now stem from what look
like PHY level error/retransmits which are impeding general throughput, incl.
AMPDU.
TX chainmask.
since the upper layers don't (yet) know about the active TX/RX chainmasks,
it can't tell the rate scenario functions what to use. I'll eventually sort
this out; this restores functionality in the meantime.
This isn't strictly required to TX (at least non-agg and non-HT40,
non-short-GI) frames; but as it needs to be done anyway, just get
it done.
Linux ath9k uses the rate scenario style path for -all- packets,
legacy or otherwise. This code does much the same.
Beacon TX still uses the legacy, non-rate-scenario TX descriptor
setup. Ath9k also does this.
This 11n rate scenario path is only called for chips in the AR5416
HAL; legacy chips use the previous interface for TX'ing.
A-MPDU RX interferes with packet retransmission/reordering.
In local testing, I was seeing A-MPDU being negotiated and then
not used by the AP sending frames to the STA; the STA would then
treat non A-MPDU frames that are retransmits as out of the window
and get plain confused.
The hardware RX status descriptor has a "I'm part of an aggregate"
bit; so this should eventually be tested and then punted to the
A-MPDU reorder handling only if it has this bit set.
The AR5416 and later TX descriptors have new fields for supporting
11n bits (eg 20/40mhz mode, short/long GI) and enabling/disabling
RTS/CTS protection per rate.
These functions will be responsible for initialising the TX descriptors
for the AR5416 and later chips for both HT and legacy frames.
Beacon frames will remain using the non-11n TX descriptor setup for now;
Linux ath9k does much the same.
Note that these functions aren't yet used anywhere; a few more framework
changes are needed before all of the right rate information is available
for TX.
function; which will be later used by the TX path to determine
whether to use the extended features or not.
* Break out the descriptor chaining logic into a separate function;
again so it can be switched out later on for the 11n version when
needed.
* Refactor out the encryption-swizzling code that's common in the
raw and normal TX path.
The higher levels (net80211, if_ath, ath_rate) need this to make correct
choices about what MCS capabilities to advertise and what MCS rates are
able to be TXed.
In summary:
* AR5416 - 2/3 antennas, 2x2 streams
* AR9160 - 2/3 antennas, 2x2 streams
* AR9220 - 2 antennas, 2x2 sstraems
* AR9280 - 2 antennas, 2x2 streams
* AR9285 - 2 antennas but with antenna diversity, 1x1 stream
After inspecting the ath9k source, it seems the AR5416 and later MACs
don't take an explicit RTS/CTS duration. A per-scenario (ie, what multi-
rate retry became) rts/cts control flag and packet duration is provided;
the hardware then apparently fills in whatever details are required.
The per-rate sp/lpack duration calculation just isn't used anywhere
in the ath9k TX packet length calculations.
The burst duration register controls something different; it seems to
be involved with RTS/CTS protection of 11n aggregate frames and is set
via a call to ar5416Set11nBurstDuration().
I've done some light testing with rts/cts protected frames and nothing
seems to break; but this may break said RTS/CTS and CTS-to-self protection.
Each different radio chipset has a different "good" range of CCA
(clear channel access) parameters where, if you write something
out of range, it's possible the radio will go deaf.
Also, since apparently occasionally reading the NF calibration
returns "wrong" values, so enforce those limits on what is being
written into the CCA register.
Write a default value if there's no history available.
This isn't the case right now but it may be later on when "off-channel"
scanning occurs without init'ing or changing the NF history buffer.
(As each channel may have a different noise floor; so scanning or
other off-channel activity shouldn't affect the NF history of
the current channel.)
* I messed up a couple of things in if_athvar.h; so fix that.
* Undo some guesswork done in ar5416Set11nRateScenario() and introduce a
flags parameter which lets the caller set a few things. To begin with,
this includes whether to do RTS or CTS protection.
* If both RTS and CTS is set, only do RTS. Both RTS and CTS shouldn't be
set on a frame.
There's two reasons for this:
* the raw and non-raw TX path shares a lot of duplicate code which should be
refactored;
* the 11n-ready chip TX path needs a little reworking.
This is just the bare minimum needed to teach ath_rate_sample to try
and handle MCS rates. It doesn't at all attempt to find the best
rate by any means - it doesn't know anything about the MCS rate
relations, TX aggregation or any of the much sexier 11n stuff
that's out there.
It's just enough to transmit 11n frames and handle TX completion.
It shouldn't affect legacy (11abg) behaviour.
Obtained from: rpaulo@
This will eventually be used by rate control modules and by the TX
code for calculating packet duration when handling rts/cts protection.
Obtained from: sam@, rpaulo@, linux ath9k
The defaults enabled three chains on the AR5416 even if the card has two
chains. This restores that and ensures that only the correct TX/RX
chainmasks are used.
When HT modes are enabled, all TX chains will be correctly enabled.
This should now enable analog chain swapping with 2-chain cards.
I'm not sure if this is needed for just the AR5416 or whether
it also applies to AR9160, AR9280 and AR9287 (later on); I'll have
to get clarification.
This, along with an initval change which will appear in a subsequent commit,
fixes bus panics that I have been seing with the AR9220 on a Routerstation Pro
(AR7161 MIPS board.)
Obtained from: Linux ath9k
PR: kern/154220
ath9k does a few different things here during config - if it's an early
AR5416 with two chains, it enables all three chains for calibration and
then restores the chainmask to the original values after initial
calibration has completed.
The reason behind this commit is to begin breaking out the chainmask
configuration for this specific reason; follow-up commits will add
the chainmask restore in the ar5416Reset() routine.
* Re-do the structure size/component math to make sure the struct matches
the expected size
* Just to be clear that we care about bitmask ordering, revert my previous
change and instead define that macro if we're on big-endian.
It turns out that the V4K eeprom definitions (used by the AR9285 and
its derivatives) is wrong. These values are at least causing issues
on my AR2427.
With this fix (and initvals in a subsequent commit), the AR2427 behaves
a lot better.
Note - there's still significant drift between the ath9k v4k eeprom
init code (again, used by AR9285 and derivatives) and what's in this
tree. That needs to be investigated and resolved.
The linux ath9k driver and (from what I've been told) the atheros reference
driver does this; it then leaves discarding 11n frames to the 802.11 layer.
Whilst I'm here, merge in a fix from ath9k which maintains a turbo register
setting when enabling the 11n register; and remove an un-needed (duplicate)
flag setting.
The v1 and v3 interfaces returned the whole EEPROM but the v14/v4k
interfaces just returned the base header. There's extra information
outside of that which would also be nice to get access to.
The rxmonitor hook is called on each received packet. This can get very,
very busy as the tx/rx/chanbusy registers are thus read each time a packet
is received.
Instead, shuffle out the true per-packet processing which is needed and move
the rest of the ANI processing into a periodic event which runs every 100ms
by default.
This is apparently an AR9285 with the 802.11n specific bits disabled.
This code is completely untested; I'm doing this in response to users
who wish to test the functionality out. It's likely as buggy as the
AR9285 support is in FreeBSD at the moment.
sys/dev/ath/ath_hal/ar5416/ is getting very crowded and further
commits will make it even more crowded. Now is a good time to
shuffle these files out before any more extensive work is done
on them.
Create an ar9003 directory whilst I'm here; ar9003 specific
chipset code will eventually live there.
with these ADC DC Gain/Offset calibrations.
The whole idea is to calibrate a pair of ADCs to compensate for any
differences between them.
The AR5416 returns lots of garbage, so there's no need to do the
calibration there.
The AR9160 returns 0 for secondary ADCs when calibrating 2.4ghz 20mhz
modes. It returns valid data for the secondary ADCs when calibrating
2.4ghz HT/40 and any 5ghz mode.
This removes the chipset-dependent TX DMA completion descriptor groveling.
It should now be (more) portable to other, later atheros chipsets when the
time comes.
The AR9100 at least doesn't have an external serial EEPROM
attached to the MAC; it instead stores the calibration data
in the normal system flash.
I believe earlier parts can do something similar but I haven't
experienced it first-hand.
This commit introduces an eepromdata pointer into the API but
doesn't at all commit to using it. A future commit will
include the glue needed to allow the AR9100 support code
to use this data pointer as the EEPROM.
the completion schedule from the hardware and returns AH_TRUE if
the hardware supports multi-rate retries (AR5212 and above); and
returns AH_FALSE if the hardware doesn't support multi-rate retries.
The sample rate module directly reads the TX completion descriptor
and extracts the TX schedule information from that. It will be
updated in a future commit to instead use this method to determine
the completion schedule.
Since we now have the source code, there's no reason to hide the diag codes
from other areas.
They live in the HAL as they form part of the HAL API and should still be treate
as "potentially flexible; don't publish as a public API." But since they're
already used as a public API (see follow-up commit), we may as well use
them in place of magic constants.
If it does, don't then try reprogramming the NF "cap" values (ie
what values are the "maximum" value the NF can be) - instead,
just leave the current CCA value as the NF cap.
This was inspired by some similar work from ath9k. It isn't
a 100% complete solution (as there may be some reason where a
high NF CCA/cap is written, causing the baseband to stop thinking it
is able to transmit, leading to stuck beacon and interface reset)
which I'll investigate and look at fixing in a later commit.
Obtained from: Linux
AR5416 and later chipsets.
ath_hal_calibrateN() calls the HAL calibrateN function with rxchainmask=0x1.
This is not necessarily the case for AR5416 and later chipsets.
flag immediately so it's only set once per longcal interval.
Without this, the current AR5416 code will continuously spam NF
calibrations during a periodic calibration if the longcal flag
is set. The longcal flag wouldn't be cleared until the calibration
method indicates that calibrations are "complete".
This drops the rate of NF calibration updates down from "once every
shortcal" (ie, every 100ms) during a periodic calibration, to only
once per "longcal" interval. Spamming NF calibrations every 100ms
caused some potentially horrific issues in noisy environments as
NF calibrations can take longer than 100ms and this spamming can
cause invalid NF calibration results to be read back - leading to
missed beacons, and thus leading to a stuck beacon situation.
Stuck beacons cause interface resets, which restart calibrations.
This means that the longcal calibration runs every 100ms (shortcal)
until all initial calibrations are completed. This spamming can then
cause the above issues which leads to stuck beacons, leading to
interface resets, etc, etc. Quite annoying.
queue length. The default value for this parameter is 50, which is
quite low for many of today's uses and the only way to modify this
parameter right now is to edit if_var.h file. Also add read-only
sysctl with the same name, so that it's possible to retrieve the
current value.
MFC after: 1 month
that generates a fatal bus trap. Normally, the chips are setup to do
128 byte DMA bursts, but when on this CPU, they can only safely due
4-byte DMA bursts due to this bug. Details of the exact nature of the
bug are sketchy, but some can be found at
https://forum.openwrt.org/viewtopic.php?pid=70060 on pages 4, 5 and 6.
There's a small performance penalty associated with this workaround,
so it is only enabled when needed on the Atheros AR71xx platforms.
Unfortunately, this condition is impossible to detect at runtime
without MIPS specific ifdefs. Rather than cast an overly-broad net
like Linux/OpenWRT dues (which enables this workaround all the time on
MIPS32 platforms), we put this option in the kernel for just the
affected machines. Sam didn't like this aspect of the patch when he
reviewed it, and I'd love to hear sane proposals on how to fix it :)
Reviewed by: sam@
* WPA-None requires ap_scan=2:
The major difference between ap_scan=1 (default) and 2 is, that no
IEEE80211_IOC_SCAN* ioctls/functions are called, though, there is a
dependency on those. For example the call to wpa_driver_bsd_scan()
sets the interface UP, this never happens, therefore the interface
must be marked up in wpa_driver_bsd_associate(). IEEE80211_IOC_SSID
also is not called, which means that the SSID has not been set prior
to the IEEE80211_MLME_ASSOC call.
* WPA-None has no support for sequence number updates, it doesn't make
sense to check for replay violations..
* I had some crashes right after the switch to RUN state, issue is
that sc->sc_lastrs was not yet defined.
Approved by: rpaulo (mentor)
MFC after: 3 weeks
o rename the new variables to comply with the naming scheme
o move the new variables to an AR5212 specific struct
o use ahp when available
o revert to previous ts_flags check
available today.
This card is a low power 802.11bgn that only does 11n rates up to MCS 7
(that's 65 Mbps in 20Mhz mode and 135 in 40Mhz mode).
802.11n is not yet supported, but will be in the future.
The driver still has a problem regarding to the setting of txpower on
the card, so don't expect good performance yet. After fixing this
problem, an MFC is possible.
Special thanks to iXsystems and S Smirnov <tonve at yandex.ru> for help
with the purchase of a netbook with this card.
Sponsored by: iXsystems, Inc.
This is needed by the upcoming AR9285 support.
Information on the layout gathered from Linux ath9k.
Not yet connected to the build.
Tested by: Eugeny Dzhurinsky
the previous ap is no longer in range) the device will deliver bmiss
interrupts and trigger the state machine. Also arrange to sync the
beacon timers on the next received beacon frame so that when we don't
roam we re-synchronize with the ap.
Tested by: trasz
MFC after: 1 week
net80211 wireless stack. This work is based on the March 2009 D3.0 draft
standard. This standard is expected to become final next year.
This includes two main net80211 modules, ieee80211_mesh.c
which deals with peer link management, link metric calculation,
routing table control and mesh configuration and ieee80211_hwmp.c
which deals with the actually routing process on the mesh network.
HWMP is the mandatory routing protocol on by the mesh standard, but
others, such as RA-OLSR, can be implemented.
Authentication and encryption are not implemented.
There are several scripts under tools/tools/net80211/scripts that can be
used to test different mesh network topologies and they also teach you
how to setup a mesh vap (for the impatient: ifconfig wlan0 create
wlandev ... wlanmode mesh).
A new build option is available: IEEE80211_SUPPORT_MESH and it's enabled
by default on GENERIC kernels for i386, amd64, sparc64 and pc98.
Drivers that support mesh networks right now are: ath, ral and mwl.
More information at: http://wiki.freebsd.org/WifiMesh
Please note that this work is experimental. Also, please note that
bridging a mesh vap with another network interface is not yet supported.
Many thanks to the FreeBSD Foundation for sponsoring this project and to
Sam Leffler for his support.
Also, I would like to thank Gateworks Corporation for sending me a
Cambria board which was used during the development of this project.
Reviewed by: sam
Approved by: re (kensmith)
Obtained from: projects/mesh11s
inbound data waiting on a filedescriptor, such as a pipe or a socket,
for instance by using select(2), poll(2), kqueue(2), ioctl(FIONREAD)
etc.
But we have no way of finding out if written data have yet to be
disposed of, for instance, transmitted (and ack'ed!) to some remote
host, or read by the applicantion at the far end of the pipe.
The closest we get, is calling shutdown(2) on a TCP socket in
non-blocking mode, but this has the undesirable sideeffect of
preventing future communication.
Add a complement to FIONREAD, called FIONWRITE, which returns the
number of bytes not yet properly disposed of. Implement it for
all sockets.
Background:
A HTTP server will want to time out connections, if no new request
arrives within a certain period after the last transmitted response
has actually been sent (and ack'ed).
For a busy HTTP server, this timeout can be subsecond duration.
In order to signal to a load-balancer that the connection is truly
dead, TCP_RST will be the preferred method, as this avoids the need
for a RTT delay for FIN handshaking, with a client which, surprisingly
often, no longer at the remote IP number.
If a slow, distant client is being served a response which is big
enough to fill the window, but small enough to fit in the socket
buffer, the write(2) call will return immediately.
If the session timeout is armed at that time, all bytes in the
response may not have been transmitted by the time it fires.
FIONWRITE allows the timeout to check that no data is outstanding
on the connection, before it TCP_RST's it.
Input & Idea from: rwatson
Approved by: re (kib)
o add HAL_CAP_BSSIDMATCH to identify parts that have the support for
disabling bssid match
o honor capability for set/get rx filter
o use HAL_CAP_BSSIDMATCH in driver to decide whether to use the bssid
match disable or fall back to promisc mode
Reviewed by: rpaulo
Approved by: re (rwatson)
