3rd Wireless Summit, Ottawa

[Nick Kossifidis]

Hello ppl ;-)

Molis xthes teleiwse to Ottawa Linux Symposium 2008 sta plaisia tou
opoiou eixame to 3o wireless summit. To wireless summit einai xontrika
ena meeting/workshop olwn twn developers pou asxolountai h
endiaferontai na asxolhthoun me wireless drivers h genikotera wireless
applications.

So merika ap' ta themata pou mas apasxolhsan kai pou vriskomaste (ena
mini report ap' to prohgoumeno wireless summit tha vreite edw ->
http://www.awmn.net/forum/viewtopic.php?f=42&t=27930):


---Status report---

QoS: Katarxas pleon exoume synolika ston pyrhna mutiqueue support, pou
shmainei xontrika oti kathe network driver sto transmit path tou
xrhsimopoiei polles oures ki etsi mporoume na ylopoihsoume politikes
QoS poly kalytera. H idea ksekinhse arxika ap' to wme pou yparxei stis
asyrmates kartes (to 802.11e orizei oti exoume metavlhta inter-frame
space kai metavlhto contention window, pou epitrepei an thelete to
kalytero dynato "strimogma" twn frames sto kanali) kai proxorise kai
stous ethernet klp drivers (perissotera edw ->
http://lwn.net/Articles/288940/). Eixame loipon mia syzhtish sxetika
me to pws xrhsimopoioume to neo framework toso sto mac80211 stack oso
kai stous drivers kathos kai mia genikh syzhthsh gia hw queues kai
aggregation (vl 802.11n parakatw).

802.11n: Enw h vasikh ylopoihsh yparxei sto mac80211, eixame mia
syzhthsh gia to pws tha "katharisoume" ton kwdika (kyriws me ta paidia
ap' thn Intel pou exoun grapsei to megalytero kommati tou) kai pws
mporoume na glytwsoume kapoio overhead klp. Syntoma tha exoume
ekselikseis sto sygekrimeno thema afou h syzhthsh htan poly
endiaferousa kai vghkan nees idees (h alhtheia einai oti me to rev.
engineering exw xasei arketes apo tis ekselikseis sto mac80211 opote
an thelete na rwtisete kati poio sygekrimeno gia to 802.11n dokimaste
thn linux-wireless).

Spectrum Management (DFS/Regulatory control):  Ena ap' ta megalytera
themata pou antimetopizoume einai ayto tou regulatory control, koinws
pws vriskoume th xrysh tomh metaksy enos open-source leitourgikou kai
twn kanonwn twn FCC/ETSI. To thema tou regulatory control empodizei
toso emas na ypostiriksoume plhrws kapoies leitourgies swsta, oso kai
tous vendors na dwsoun open source drivers (mias kai fovountai oti h
FCC tha tous kinigisei). Eixame poly entones ekselikseis prosfata
loipon afou h Atheros edwse open-source ton neo ths driver ath9k, pou
ypostirizei ta kainouria 802.11n chipsets (oxi mono ta ar9xxx alla kai
to AR5416/AR5418) ths kai pou exei vrei to dromo tou gia ton kernel
(mallon ap' thn ekdosh 2.6.28), prokalontas tous ypoloipous vendors
(kai kyriws thn broadcom pou efage xontro giouxarisma) na kanoun to
idio. H thesh loipon ths Atheros (meta apo POLYYY syzhthsh telika
phstikan) einai oti telika kaneis den mporei na ftiaksei mia lysh pou
tha einai 100% asfalhs, oti to "security through obscurity" den
poianei kai oti akoma kai etairies pou xrhsimopoioun firmware, exoun
hackeftei (mpixth gia thn broadcom opou ta paidia pou kanoun rev.
engineer kontevoun na grapsoun open-source firmware :P). Etsi anti na
kanoun thn papia prospathoun na apotrepsoun to abuse twn kartwn tous
apo tous reverse engineered drivers kai gi' ayto synergazontai energa
me thn koinothta pros ayth th kateythynsh (siga siga tha doulepsoume
mazi kai ston ath5k). Exei mpei se troxia o Central Regulatory Domain
Agent, ousiastika prokeitai gia ena framework pou tha yiothetisoun oi
drivers kai vasei tou opoiou tha rythmizoun (h kalytera tha kanoun
limit) to transmition power kai to evros twn syxnothtwn pou
ypostirizoun se kathe xwra. Perissoteres plhrofories edw ->
http://wireless.kernel.org/en/developers/Regulatory. Kapoia updates
sto keimeno einai oti den tha xrhsimopoioume kapoion extra daemon alla
to udev, px. opws fortwnetai to firmware otan kanoume up ena
interface, tha fortwnetai kai h database pou antistoixei sth xwra pou
vrisketai xrhsimopoiwntas plhrofories toso ap' to 802.11d oso kai apo
thn idia thn karta, px EEPROM. Gia tis kartes pou den exoume tetoies
plhrofories (dld oses exoun ginei rev. engineering kai den parexoun
plhrofories gia to regulatory domain px. -pali mphxth sthn broadcom
:P-) tha prospathoume na pairnoume kapoia plhroforia ap' to userspace
(px. na orizei o xrhsths th xwra pou vrisketai -analamvanontas thn
eythinh panta-). Telos yphrkse mia idea gia enan Frequency Broker pou
ousiastika tha einai ena framework h daemon pou tha epilegei
kanali/mpanda xrhsimopoiwntas plhrofories apo olles tis asyrmates
syskeves pou diathetei to pc, px. an exete energopoihmeno bluetooth,
tha kserei apo prin se poia syxnothta paizei, opote den tha thn
xrhsimopoiei px. gia wi-fi an pate na sthsete ap.

802.11s (wireless mesh): An kai to 802.11s einai akoma draft, ta
paidia pou doulepsan sthn ylopoihsh tou sto OLPC (sto firmware twn
Marvell -h opoia fainetai na to gyrizei ksafnika kai ayth se
open-source !), ylopoihsan to kainourio draft (oxi plhrws alla kanei
ta vasika) sto mac80211. Syzhtisame loipon pou vriskomaste, ti leipei
ap' to implementation (kai ap' to draft) kai epishs mathame oti to
implementation sto mac80211 den einai symvato me to implementation tou
OLPC to opoio vasizetai se paliotero draft (ara den mporeite na
sthsete mesh diktyo metaksy OLPC kai kapoiou mac80211 driver). To
802.11s exei apoktisei poly endiaferon kai arketoi doulevoun se ayto
(erevnhtika idrymata klp) kai anamenoume ekselikseis, pantws mexri
twra to Linux einai to mono leitourgiko pou ylopoiei ayto to protypo
kai to kataxarhkame :P

RF Kill/Power management: To RF Kill einai ena framework gia na
xrhsimopoioume ta diafora switches (hw/acpi/sw -px fn + kati) twn
laptops gia na anoigokleinoun tis asyrmates kartes (bluetooth/wi-fi
klp). To kyriws provlhma htan me to firmware loading stis kartes pou
to xreiazontai kai ti akrivws kanoume se mia periptwsh pou to switch
energopoieitai h apenergopoieitai. Alloi elegan oti to RF Kill prepei
na kanei apla disable to PHY kai oxi synolika thn karta gia na mporoun
oi kartes pou xrhsimopoioun firmware na epanerxontai poio grhgora klp,
alloi -symperilamvanomenou ki emou- pistevane oti to RF Kill prepei na
einai to idio me to ifconfig down (na rixnei dhladh teleiws thn karta)
klp. Katalhksame loipon sto oti prepei otan to switch einai kleisto na
vazoume thn karta sto ypsilotero dynato power save mode kata to opoio
mporei na epanelthei xwris na ksanafortwsoume ton driver, an h karta
katanalwnei energeia otan exei loaded firmware, tote thn rixnoume, an
oxi apla thn kanoume reset kai thn afhnoume na kathetai -yparxoun
kartes pou den katanalwnoun energeia otan einai apla up, akoma kai
kartes pou xrhsimopoioun firmware, opote se aytes den kanoume ifconfig
down px-. Ayto akougetai aploiko alla den einai, prokyptei ena
provlhma me kapoies kartes pou xreiazontai firmware px. gia na mas
kanoun report thn MAC address tous (kai ara tha exoume provlhma px. me
to udev kai to renaming twn kartwn) kai prokyptoun kai alla themata
(px. wake on wlan klp). Gia to thema ths MAC fainetai na katalhksame
(vl. prosfato patch sthn linux-wireless) sto oti otan h karta den mas
kanei report th MAC otan einai down/rf-killed, tha ths vazoume
manually thn 01:00:00... (h 00:00... einai registered :P). Opote ama
deite kamia periergh mac kai kana periergo onoma sto wi-fi interface
sas (giati kata pasa pithanothta tha enhmerwsoume kai to udev gi'
ayto), mhn psaxneste.

Driver Status: Kaname o kathenas mia parousiash sxetika me to pou
vrisketai o kathe driver kai genikws ta pragmata pane poly kala,
eimaste ap' tis poio energes omades ston kernel (4h se commits) ! Tha
exete poly kalyterh eikona an deite th lista linux-wireless (to wiki
einai ligo outdated) gia to pou vrisketai o kathe driver. Oson afora
ton ath5k, prosfata esteila ena patch series pou ypostirizei tis pci-e
kartes symperilamvanomenhs ths RF2425 (ayth pou exei to eeepc), opote
kleisame me to support twn legacy kartwn (a/b/g) kai menoun oi 11n
(pou ypostirizontai ap' ton ath9k -vl parapanw- me ton opoio kapoia
stigmh tha kanoume merge) kathws kai ta diafora themata performance.
Mporeite na vreite ena snapshot edw ->
http://www.kernel.org/pub/linux/kernel/people/mickflemm/compat-wireless-2008-07-03-ath5k.tar.bz2,
enw ta patches gia to wireless-testing tree tha ta vreite edw ->
http://www.kernel.org/pub/linux/kernel/people/mickflemm/patch-series-8.tar.bz2.
Exoun hdh ginei submited kai syntoma tha ginoun commit. Eixame epishs
kapoies anafores ap' thn intel sxetika me tous iwlwifi opou
diorthwnoun diafora bugs kai strwnoun ton kwdika (idiaitera oson afora
to 11n kommati), enw exoun vgei kata kairous kai diafora endiaferonta
patches metaksy twn opoiwn ki ena pou ypostirizei packet injection.
Oson afora ton b43, to rev. engineering exei sxedon teleiwsei, ta
specs grafontai klp kai menei na graftei o kwdikas (clean room), ta
paidia exoun sxedon grapsei diko tous firmware to opoio omws sth
parousa fash kanei hang meta to prwto paketo pou kanei transmit (kanei
rx kanonika). H Broadcom arneitai na dwsei specs h kwdika (steilan
omws ton Henry o opoios einai poly kalo atomo kai prospathei ki o
idios na tous pisei -to ti akouse o kakomoirhs de legetai :P- kai
fainetai na skeftontai toulaxiston to licensing tou firmware) alla ta
paidia tou b43 einai apofasismenoi na tous apoteleiwsoun :P. Eixame
epishs enan apo th Ralink o opoios den evgale axna :P.

---Current work---

AP (master mode) support: O kwdikas gia thn ypostiriksh master mode
yparxei hdh sto mac80211 stack alla akoma kapoia scenarios den exoun
ylopoihthei kai ws ek toutou den einai akoma standards-compliant.
Epishs exoume akoma poly douleia oson afora to DFS (aparaithto an
theloume na sthsoume ena AP sta 5Ghz -einai kommati tou protypou
802.11a), to APSD (automatic power save delivery) kai to U-APSD
(urgent automatic power save delivery). Syntoma elpizoume ayth h
leitourgia (pou th zhtaei polys kosmos) na einai diathesimh gia tous
xrhstes (pros to paron xreiazeste ena patch gia na peiramatisteite
-rixte mia matia sthn lista linux-wireless).

cfg80211/nl80211: Syzhtisame gia to pote tha ksefortwthoume ta
wireless extentions kai pote tha proxwrisoume pros to userspace MLME.
Den katalhksame kapou alla genikws eipame oti exoume ftasei se ena
shmeio opou ta wireless extensions mas kratane pisw sto development,
enw xreiazomaste perissoterous developers na asxolithoun me to
sygekrimeno API afou o Johannes exei minei monos tou.

CRDA: vl. parapanw (spectrum management)

Encrypted management frames (802.11w): O kwdikas einai sxedon etoimos
kai apla epivevaiwsame oti to implementation proxwraei kanonika kai
otan erthei to userspace MLME tha eimaste etoimoi.

Hw simulator: Exoume pleon ap' ton Jouni enan simulator gia na
mporoume na testaroume to protocol stack. Ousiastika prokeitai gia ena
virtual hw interface me ton driver tou, panw sto opoio mporoume na
treksoume diafora tests, injection klp. Den exoume etoima test scripts
akoma alla exei parei to dromo tou...

WiMAX: H Intel mas ekane parousiash tou framework pou exei ftiaksei
gia to support twn wimax kartwn ths sto linux (vl.
http://www.linuxwimax.org/) kai mas eksighse perippou ti paizei me
tous providers kai ti apaithseis exoun klp. En oligois oi perissoteroi
service providers exoun ws apaithsh oi kartes na einai fullmac (h
syzhthsh ksekinhse gia to an mporoume na exoume master mode sto
wimax), enw prepei na ylopoihsoume diafora pragmata sto userspace
(deite to site kai tha katalavete). H Intel mas edwse merikes kartes
(engineering samples) wimax + 11n gia na paiksoume kai na ths
steiloume feedback.

---Future work---

lib80211/full mac drivers: Oi kartes full mac, ylopoioun olo to 802.11
stack sto firmware kai ara gia ton pyrhna einai apla ethernet devices.
Akoma omws kai oi fullmac drivers exoun arketa koina xarakthristika
kai vlepoume syxna code duplication. Gia kairo syzhtagame gia ena allo
framework pou to eipame lib80211, gia tous fullmac drivers, etsi wste
na glytwsoume apo ayto to fainomeno (px.
http://article.gmane.org/gmane.linux.kernel.wireless.general/8746).
Telika fainetai oti to cfg80211 einai poio endiaferon kai mallon o
koinos kwdikas tha paei ekei.  Ousiastika to mono pou xreiazomaste
ston driver einai na ylopoiei to cg80211 API (gia na mporei na
rythmizetai h karta -essid klp-), etsi gia tous fullmac drivers mallon
tha ftiaxtei kapoio estention sto cfg80211, akoma den to exoume
ksekatharisei.

Rate control algorithms: Mexri stigmhs exoume enan default algorithmo
gia rate control, ton PID controler
(http://en.wikipedia.org/wiki/PID_controller), gia olous tous drivers,
ti ginetai omws an kapoies kartes/drivers exoun parapanw capabilities
pou vohthoun sto rate control ? H kalytera oios tha htan o kalyteros
tropos na exoume px. vendor specific algorithmous, opws px. o minstrel
(vl madwifi) h oi algorithmoi ths Intel ? Mexri twra oi drivers ths
Intel toulaxiston, xrhsimopoioun ton diko tous rate control algorithmo
ws ksexwristo module. Meta eipame oti to idaniko tha htan oi
algorithmoi na einai meros tou mac80211 kai oxi ekswterikoi kai telika
symfwnisame se ena evelikto tropo epiloghs rate control algorithmou
apo ton driver, xrhsimopoiwntas capabilities klp, dinontas isws se
kapoious drivers th dynatothta na xrhsimopoihsoun kapoion apo tous
vendor specific algorithmous an ploiroun ta aparaithta capabilities
(p.x. MRR). Ayto vevaia menei na ylopoihthei, prepei kapoios na katsei
na dei ton kwdika apo olous tous algorithmous, na kanei to
kseskartarisma klp (psinetai kaneis sas ?).


---Various stuff---

Mias pou phgame sthn Ottawa, apofasisame na katsoume kath olh th
diarkeia tou OLS, o John Linville (o kernel maintainer gia tous
wireless drivers) ekane mia parousiash (BoF) thn opoia mporeite na
deite edw -> http://www.kernel.org/pub/linux/kernel/people/linville/ols2008/presentation.pdf,
enw eixame kai alles syhtiseis toso mesa to OLS, oso kai ston kafe
klp. Genikws perasame yperoxa kai gnwristikame kalytera metaksy mas,
hpiame arketes mpyres, xorepsame salsa -enas developer ap' thn Intel
xorevei apistefth slasa btw-, fagame mexri skasmou klp. Enas developer
ap' to Ubuntu phge kai epekse live (ekane sign se open mike session)
se ena magazi ekei konta (me thn carbon fiber ! kithara tou) kai
phgame na ton doume (egine anarpastos) opote giname liwma
-koimhthikame stis 4 kai mas stamathse ki enas astynomikos sto dromo
giati perasame me kokkino stis 3 :P-. Thn teleytaia mera phgame oloi
se ena bar pou htan olo gia parth mas (private party + open bar :P)
kai ksanaginame liwma (ekei btw eixe kai tis mones sovares mpyres),
enw thn Kyriakh sthn Ottawa kleinoun tous dromous to prwi gia
podhlata, opote kaname to gyro ths polhs (efaga kai mia kalh savoura
:P) kai katalhksame se ena parko opou to ekei lug mas eixe sthsei BBQ
! Htan teleia ! Dystyxws ap' tou xronou katedafizetai to Rideau center
opou ginotan mexri twra to OLS alla to synedrio tha metaferthei telika
sto Montreal, opote dwsame rantevou gia ekei...

Grapsame ligo kwdika sxetika me to CRDA, kaname kapoies syzhtiseis
peretairw gia to AP support kai to pws o Jouni, twra pou einai sthn
Atheros tha doulepsei arketa se ayto kai syzhthsa me ton Luis kai ton
Jouni gia to pws tha kanoume merge ton ath5k me ton ath9k (toulaxiston
na mazepsoume ta common kommatia tous). Epishs megalh entyposh ekane h
kinhsh ths Atheros me ton ath9k, toso ta paidia ap' thn Intel oso kai
apo thn Broadcom eixan meikta synaisthimata, ap' th mia fovountai mia
kinhsh ths FCC enantion ths Atheros pou ousiastika tha xtypisei
kampanaki kai stis dikes tous etairies kai olh h prospatheia pou
ginetai gia na proxwirsoun pros open-source lyseis tha paei strafi
(koinws fovountai oti h Atheros prokalese). Ap' thn allh omws an ola
pane kala tha exoun poly perissotera epixeirhmata na peisoun kai oi
idioi (idiaitera h Broadcom) tis etairies tous pros ayth th
kateythynsh. Ena allo thema pou sxedon ekseplhkse einai oti h Marvell
fainetai epitelous na asxoleitai me Open Source lyseis, einai sta
skaria enas kainourios open-source driver gia tis asyrmates kartes
tous, enw gia prwth fora esteilan arketo kosmo sto OLS pou asxoleitai
oxi mono me wireless alla kai me alla themata -p.x. proselavan kapoia
paidia pou doulevan sto ARM support ston kernel-. Syzhtisame arketa
gia ton Network Manager ai diafora themata sxetika me to d-bus, ton
wpa_supplicant, to aggregation twn queues sto 802.11n, kathos kai me
xrhstes pou eixan apories gia tis kartes tous. Telos kath' olh th
diarkeia tou event yphrxan arketes etairies pou ekanan recruit, me thn
Intel kai thn Wind River na exoun kleisei thn executive suite (sxedon
misos orofos) gi' ayth th douleia. An kapoios apo esas psinetai na
asxolhthei me wireless development mporei na stilei cv sth dieythynsh
wireless at linux.intel.com gia thn intel -oi opoioi ap'oti katalava
efygan me adeia xeria giati den vrhkan kosmo- (gia th windriver den
thymamai alla logika kati tha leei sto site tous). Epishs kai h
Atheros psaxnei kosmo (kyriws gia douleia sthn India) kai h cozybit (h
etairia pou doulevei sto 802.11s, sto OLPC klp) psaxei epishs kosmo.
Ttha phgaina egw se kapoia (mias pou mou to protinane kai oi 4 :P)
alla den exw teleiwsei me th sxolh mou akoma, exw kai to fantariko
opote mou einai idiaitera dyskolo se ayth th fash -h Wind River kai h
Cozybit pantws mporoun na proslavoun kai gia part time an kapoios
endiaferetai-, an kapoios apo esas omws exei asxolhthei sovara me to
thema mporw na vohthisw.

Ayta apo emena, sorry pou den grafw syxna sth lista alla dystyxws pizw ;-(

Kleinontas thelw na eyxaristisw to ergasthrio sto opoio doulevw
(http://www.ics.forth.gr/tnl/) pou me vohthise me ta eksoda tou
ksenodoxeiou -par olo pou emai pro-ptyxiakis kai h douleia mou ekei
den sxetizetai amesa me ton ath5k- kathws kai ton T. Karouno pou me
vohthise me ta eishthria (poy htan kai to megalytero kostos). Xwris
thn stiriksh tous den tha mporousa na paw sthn Ottawa (kanonika tha
eixa sponshorship ap' to Linux foundation alla eixan ena event
kapoious mhnes prin kai eixan kseminei, enw to MadWiFi team mou
proteine epishs kapoia vohthia alla arnhthika giati ta donations ta
exoume gia to testing lab mas). Genikws to oikonomiko einai ena
provlhmma, idiaitera otan eisai foithths kai den mporeis na vreis full
time douleia logw twn synthikwn. Kalo tha htan na exoume kati poio
organomeno giati eimai sigouros oti yparxoun arketa paidia pou theloun
na asxolhthoun me antistoixa projects kai na parakolouthisoun kapoia
apo ayta ta events alla den eixan thn idia tyxh me emena.


Na 'ste oloi kala ki elpizw na sas petyxw se kana
mpyro/kafe/masa-meeting. Kalh synexeia sta projects sas ;-)

-- 
GPG ID: 0xD21DB2DB
As you read this post global entropy rises. Have Fun ;-)
Nick