Jérôme Lambourg

Cross & BareBoard team Inside Out

GNAT Pro team co-lead

I can hear you think…

Theyshouldsaybarebored.

Ohmy…

Bareboard??

Ah!Aperfecttimeforagoodnap…

Hey,Iwokeupearlytoattendthismeeting!

I can hear you snor…

Even from outer space…

DammitJim!Thisisnotlogical.

Notanelectricalengineer!

I’m aprogrammer

ANYWAY, LET’S GIVE IT A TRYThislooksboring indeed…

Agenda

•What'snewinVxWorks 6533.x (Doug)• Binutils internals(Tristan)• GCC:configuration tipsandtricks(OlivierH)• Qemu:howtoimplementanewboard(Fabien)• GprBuild:howtoaddanewtoolchain (Joel)• CompletehistoryoftherelationshipbetweenAdaCore andWindRiver (EdF)

This is really about

OurDailyactivities

What makes us wake up in the morning

GNAT Pro for Cross & BB

DebuggingEmulatorsSimulatorsBoards

TestSuites

Production

GprBuild, tools

BinutilsIDEs

GCC/GNATRuntimes

GNAT Pro for Cross & BB

BinutilsCompilerRun-timeQemu

gprbuild

production

Debugger

GPSGnatBench

CPUscoprocessorsBoards ABI

certification

Real-time

OS(crossonly)

Making it work together

Sales

Strategy

Marketing

Roadmap

Certification

CROSS DEVELOPMENTPARTI

Example: Investigating Cross issues

"A Cross never, ever marks the spot"Indiana Jones

Thecrime

An aCATs test FAILS on e500v2-vx7

Blargh, I is DED on e500v2

Usercode

AdaRun-time+compiler

OS

Context

Board

Signal raised

Translated into exception

Exception handler

Theissue:exceptionhandlerisnever

calledToomuchmemory

used

JeromeL* WhyisitworkingonPPCandnotone500v2?Joel* Goodluck!CrossingfingersEdF* Thisremindsmeofsomegoodoldbug.Thosewerethe

days.Doug* SimilarissueherewithZCXonvx6forx86,willkeepyou

postedJeromeG* Guys,IneedtotakemyThursdayoffnextweek.

*Allcharactersappearinginthispresentationarefictional.Anyresemblancetorealpeopleispurelycoincidental.

Usercode

AdaRun-time+compiler

OS

Board

Signal raised

Translated into exception

Exception handler

Toomuchmemoryused

Wow!Thislooks

complex

Investigate the crime scene

Need help

• AfteracompleteexplanationfromOlivierH oftheexpectedmechanism,Icanresumethedebug.• Whenallocating theexceptionoccurrence,Itlookslikesomethingweirdhappensaroundafunctioncalled"AbortDefer"

Let'scheckthe(CRM)

A guess!

Someoldcase(e.g.TN)referstoissues aboutcallstoAbortDeferfromasignalhandler

Theruntimeistheculprit!!!!!!

Transmit to court (e.g. send an email)

Arno should never happen, allocating exception blah blah blah certification blah blah

OlivierH not an issue blah blah ZCX-specific blah blah

Arno what about BE SJLJ? blah blah

OlivierH indeed blah blahArno in case of tasking blah blah

JeromeL Ah! No tasking involved in this case

Arno then not the issue here, case dismissed, and transferred to the certification court

So let's continue the investigation!

More debugging

…Let’sdigfurtherandstepintoassembler instructions

Debugger log

ØAnunexpectednewsignalisraised (Ah!Ah!Recursivesignals!)

*Allinstructionsappearing inthispresentationarefictional.Anyresemblance torealinstructionsispurelycoincidental.

(gdb) disassemble $pcevaddsmiaaw* … …(gdb) siComputer says No: boom

(Show me the code)(Some code)(Execute it)(or any similar output)

Ø It's an E500v2-specific instruction (YES!)

Second guess

Somee500v2instructionisnotproperlyexecutedbyQEmu?

Qemu istheculprit!!!!!!

Transmit to court (Fabien, Qemu expert)

• DiscussingwithFabien,itturnsoutthatSPEsupportisOKinQemu…socasedismissed(again)

• However,duringthediscussion,headvisesmetocheckthe« MSR »

:MachineStateRegister. Ah!

: SPE instructions are available only when a specific bit is set on the MSR. Else a sigill signal is raised. Ah! Ah!

Google is my friend

:answersmanythings,abouttents,videogames,guns,etc.

MSR

MSRPowerPC

MSRe500v2SPE

Third guess

MaybeVxWorks isnotproperlysettingthebitwhencallingasignalhandler?

VxWorks istheculprit!!!!!!

Transmit to court: send a TSR to WindRiver

• WriteasmallCreproducerthatchecksthespecifiedbitintheregister.=>bitnotset wheninthehandler,setotherwise (youhou!Foundit,foundit!Youcannowsafelybragaboutitwithyourcolleagues)

• TransmitcasetoWindRiver• SolutiondiscussedwithWindRiver

I is OK now!

Thankz!

BARE METAL DEVELOPMENTPARTII

Bare metal* ?

• AboutrunningsoftwarewithoutanyOperatingSystem

• Thisgivesyoufullcontroloverwhatisrunning

* SameasBareBoard,butit’scool

Pros

Realtimeproperties

• Does notmean FAST…• Means ontime!

• Execution timeis predictable• Keyword:« Ravenscar »

Pros

Reliability,certification– Everything that is onboard is under control– Very small footprint– Nobugsfrom theOS

Cons

Softwaree.g.alotofmanual work

DIY

OK, YOU CONVINCED ME:

I BOUGHT THE BOARD XYZ FROMVENDOR ABC.

I WANT TO RUN ADA.

HOW DO I DO THAT?

Well, you can ask usHaveyoucheckedwithSalesfirst?

PatR. Fabien Tristan PatB. Jerome L.

You can also try it by yourself…

First,you need aboard:

Silicium PCB:fiber glass+copper Ceramics

Soldering Plastic Gold, silver, copper…USBportonyour

host

may come pre-assembled in variousshapes and colors

You’ll also need:

• Youwill need docs(such astheARMARM).• Andmoredocs(such astheMCUrefmanual)• Peopletohelpyou finding thedocsyou’remissing (such astheboard schematics)• Some updated docs• Internet&asearch engine (ifyou don’tknowone,letmegoogle that foryou…)

Major steps to move forward

1. Power-uptheboard2. Connect toit3. Create anAdaruntime fortheboard4. Create anexample5. Load theexample into theboard

I. Power up the board

Plugtheboard• See that it’s powered (at leastaLEDshould lightup)

• Ifnot, read thedoconhowtoplug andpoweruptheboard

II. Connect to the board

e.g.find away tocommunicate with thetargeted board

II. Connect to the board

Lookforaway toconnect toit• Lookat thedocthat comes with theboard• Youcan also search theinternet• Youmay ask Tristan*• OrFabien**• OrAnthony*** tocreate aGPSpluginforyou

* Maybe busy,orplaying fussball**Mayalso be busy,butdoes notplay fussball***plays fussball alot

III. Create an Ada runtime

Well,here’s atough one• Ifwe already haveasimilar board supported,theruntime may only needminor adjustments:• Memorymapping (e.g.read thedoc),interrupts (c.f.doc),clock speed(RTFM)• Ifyou’re interested,gosee:blog.adacore.com/porting-the-ada-runtime-to-a-new-arm-board

• Else,you can contactsales@adacore.com ;)

At this point

• What you haveis:1. Aboard that is powered on(e.g.red led on)2. Some tool claiming itmay controltheboard3. Aruntime that you haven’t tried yet (e.g.aschrodinger runtime:it both works

anddoesn’t)

Iiz and iznota

runtime

Butpliz don’topenthebox

IV. So now is the time…

1. Turn aLEDON2. Wait abit3. Turn theLEDOFF4. Wait abit5. Goto1

…Forthefamousbaremetalhelloworld:“TheblinkingLED”

Scenariois very complex:

IV. The LED example

This« simple »example implies many readings• MCUreferencemanual (ordatasheet):initialization ofthe« GPIO »,theGeneralPurpose I/Osystem.• Board schematics,tofind outonwhich pinoftheGPIOtheled isconnected to.

Thisone?

V. Run all this on the board

Onceyou seem tohaveeverything setup:• Crossyour fingers• Load theexample onboard

Iiz bored.Pliz try again

– Either you endupwith what lookslike abrick

– Oryou can celebrate with ablinking LED(HEY!Comeonandlookatmy LED!Howfun!)

From there, fancy stuff coming!

You’re now ready tocreate aninfinity ofvery fancy stuff …

Fancy stuff (1)

Demos

Fancy stuff (2)

Candydispenser*

*Eat 5fruitsandvegetables aday tokeep healthy

Fancy stuff (3)Flightcontrollers fordrones

Ibelieve Icanfly…

… andlandsafely!

Fancy stuff (4)

Space stuff

Hey!Theauto-landingoftheCrazyflie

doesn’t work here!

Fancy stuff (5)

Ultimate LEDdemo*

*Children:don’t try this at home

WHAT’S NEW?

Some figures: cross & BB products

supported products

new products

Bare Metal: Improvements

• ExtendedRavenscar tasking• Better than state-of-the-art

• MoreCPUs supported• Inparticular Cortex-A

• Multicore (SMPsupport):• Leon,Cortex-A,PPC

Widening the Ada audience

LeverageonthebuzzaroundARMbaremetaldevelopment

Widening the Ada audience

Atwo stagesstrategy

1. Making GNATready-to-use forthose bare metal enthusiasts

2. Making sureeveryone knows aboutthis effort

Widening the Ada audience

Make GNATready-to-use onmany boards• Runtimes:moreboards supported (GPL+github)• SVD2Ada• AdaDriversLibrary

Thisis also meant tohelpyou,notjust newcomers!

Widening the Ada audience

Advertising GNATforARM• Make with Adablogposts• Howtoadapt theruntime blogpost• community.arm.com blogpostonAdaforBB• Make with Adacontest

That’s it!

Thank you foryour attention!

At leasthe didn’tmentioned IOT.

Fine…