[ANSOL-geral] Novena: A Laptop With No Secrets

Andr Isidoro Fernandes Esteves aife netvisao.pt
Quarta-Feira, 28 de Outubro de 2015 - 00:28:15 WET


Tive a oportunidade de ver um no CCC deste ano e é uma máquina doce, 
doce, doce... :P
1ab,
André Esteves


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  Novena: A Laptop With No Secrets


    How we built a laptop with nothing but open-sourced hardware and
    software

By Andrew “bunnie” Huang & Sean Cross
Posted27 Oct 2015 | 21:00 GMT
/img/011ExplodedviewBuildupTeardownScottTorborgCrowdSupplyFM7A2296-EditV2-1445881964242.jpg 

Photo: Scott Torborg/Crowd Supply

*Has the computer become a black box, even to experienced electrical 
engineers?*

Will we be forever reliant upon large, opaque organizations to build 
them for us? Absolutely not, we say. And to prove our point,we built 
<http://www.kosagi.com/w/index.php?title=Novena_Main_Page>our very own 
laptop, from the circuit boards on up.

Admittedly, we did not delude ourselves that we could build a laptop 
that would be faster, smaller, or cheaper than those of Apple, Dell, or 
HP. However, we did set out to build a machine powerful and convenient 
enough to use every day. Fortunately, our dream inspired enough people 
to crowdfund the effort. Our laptop, which we call Novena, started 
shipping to backers in January 2015.

Events favored our quest.Because Moore’s Law is slowing down 
<http://spectrum.ieee.org/semiconductors/design/the-death-of-moores-law-will-spur-innovation>, 
garage innovators can take a couple of years to develop a high-tech 
gadget without discovering that the completed version is obsolete. It 
has been three years since we started the Novena project and yet the 
40-nanometer process on which our central microprocessor is based 
continues to occupy a sweet spot between cost and performance.

Also, the economic malaise of 2008 left a lasting mark on global supply 
chains. Even today, manufacturers are no longer too busy printing money 
to make the time for producing small, boutique projects like ours; 
instead, they see us as an opportunity to gain an edge over their 
competition. Owners of small factories in China turned out to be eager 
to learn our agile approach to engineering, so they, too, could take on 
the challenge of low-volume production and address the growing market of 
hardware startups.

*We started by considering*the constraints of the most complex and 
brittle pieces of any such system: the software. We wanted to build a 
complete computer, one with a long-term-support road map, and we had 
neither the resources nor the manpower to negotiate with vendors of 
proprietary hardware and software. We wanted to be able to inspect and 
understand as much of the system and its components as we could, so if 
we came across bugs or other anomalous behavior, we could rely on our 
wits to figure it out, rather than on the profit-motivated (and often 
empty) promises of a vendor‘s sales team. As a result, we decided to 
produce a laptop that was as free as possible of closed-source embedded 
firmware.

Firmware is basically software (such as drivers, kernels, and 
bootloaders), installed at the factory, thatruns on “bare iron” 
<https://en.wikipedia.org/wiki/Bare_machine>—the computer itself, not 
its operating system. It’s found not only on the main CPU in your laptop 
but also on about a dozen embedded controllers—small, special-purpose 
processors that take care of such things as managing the battery, 
keeping your hard disk free of errors, and maintaining your Wi-Fi 
connection. Each of these processors runs a bit of firmware; sometimes 
the firmware can be updated or modified, typically for the purpose of 
fixing bugs or adding features. But such updates can also introduce bugs 
or security flaws, and if you haven’t got the ability to inspect the 
firmware, then you, the user, must depend utterly on the vendor to take 
care of security.

/img/HRLaptopKeyboardremoved-1445884800912.jpg/img/041LaptoprearCampaignimagesScottTorborgCrowdSupplyNovena-1089-1445884407092.jpg 

Photos: Scott Torborg/Crowd Supply

*Laptop, Open Wide:*The Novena opens to reveal the circuit boards; when 
it’s closed, the outward-facing display lets you use it like a tablet.

This open-source requirement of ours ended up influencing the selection 
of almost every piece of hardware, including the main CPU, the battery 
controller, and the Wi-Fi module. For example, we couldn’t use Intel’s 
x86 microprocessors because they can accept firmware updates that we 
cannot debug or inspect. Instead we chose an ARM-based Freescale 
i.MX6system-on-a-chip <https://en.wikipedia.org/wiki/System_on_a_chip>, 
which has no such updatable code embedded. (A system-on-a-chip, or SoC, 
is similar to a microprocessor except it has more of the supporting 
hardware, such as memory and peripheral interfaces, needed to make a 
complete computer.) The i.MX6 does have some code burned into it to 
coordinate the computer’s boot-up process, but this firmware can’t be 
changed, and its unencrypted binary code can be read out and analyzed 
for possible security problems.

Another advantage was Freescale’s policy of distributing a very detailed 
reference manual covering most of the chip’s real estate without 
requiring a nondisclosure agreement. That’s important because such an 
agreement would have gotten in the way of the community involvement that 
our strategy for long-term support required.

Our next choice had social repercussions. When you adopt a 
CPU/operating-system combination, you also adopt its developers. We 
decided against Google Android because it’s optimized for phones and 
tablets, its graphical display typically shows only one application at a 
time, and its touch-screen paradigm is too imprecise for computer-aided 
design work. Therefore, in order to create a system that our target 
market of developers and creators could use, we decided to run on our 
ARM chip a version of Linux called GNU/Linux. GNU, which authored both 
the OS libraries and the license that the Linux kernel uses, is a 
coder’s organization, right down to the self-referential acronym itself 
(it stands for “Gnu’s Not Unix”).

Unfortunately, most Linux versions for ARM were not designed for 
personal computing but rather for routers and the set-top boxes that 
convert signals for viewing on televisions. Manufacturers that use Linux 
generally build their own, highly customized system around what’s called 
the Linux kernel—the core framework of the OS. That way, they ensure 
that their customers, who integrate the software into a larger system, 
never see so much as a Linux command prompt. Examples include TiVo and 
airline in-flight–entertainment systems. On top of that, vendors use an 
old “snapshot” of Linux—that is, they copy whichever kernel is around at 
the time of chip release. Then they add a lot of patches to it to create 
a board support package (BSP) for their product, which is a kind of 
“quick start” kit for hardware developers who don’t want to muck around 
too much with Linux kernel minutiae.

Frequently these BSPs contain proprietary bits that developers can’t 
copy, that don’t take advantage of features that came with the original 
kernel, and don’t even follow the standard formatting procedures for 
Linux code. These undisciplined shortcuts may speed a product to market, 
but they make the kernel impossible to maintain, update, or improve. As 
a result, most systems that are based on Linux run kernels that are 
years out of date. This is not a plan for long-term customer support.

Therefore, we adopted the latest kernel available. We patched and 
extended Freescale’s open-source BSP code to comply with Linux community 
standards, then submitted our changes to the managers of the Linux 
community at large. They reviewed our code and provided feedback over 
several months of iterations.

At that point, our code was finallyready to be “upstreamed” 
<https://en.wikipedia.org/wiki/Upstream_%28software_development%29>into 
mainline Linux. It’s a time-consuming and laborious process, but when 
it’s over the Linux community can adopt our version and maintain it. The 
main advantage of this upstreaming process is that features that come 
with future Linux kernels can be unlocked by simply downloading the 
latest version of the operating system and compiling it, without having 
to repeat the code-review process.

Hardware-accelerated graphics proved to be another challenge. Most 
modern desktop computers assign each application or graphical widget an 
off-screen memory buffer to render their output on the screen. Only then 
does the graphics processing unit (GPU) “composite” the various outputs 
to make the seamless image seen on the screen.

This two-step process decouples the application’s drawing rate from the 
screen’s refresh rate,preventing a “race condition,” 
<https://en.wikipedia.org/wiki/Race_condition>in which two input signals 
compete to be the first to affect the output. Such racing can produce 
artifacts such as “tearing,” in which the attempt to drag a window ends 
up moving only the top part by the time the screen refreshes. The newly 
redrawn half of the window closest to the cursor thus looks torn off 
from the lower half. Also, the two-step decoupling process can be used 
to create subtle cues, such as transparency and blur, where foreground 
windows and title bars can take on the character of frosted glass, 
providing a hint of what content might lie underneath them.

Unfortunately, the integrated GPU on the Freescale i.MX6 chip is closed 
source. Remember how we said that the vendor-supplied BSPs are typically 
snapshots of older kernels? The code that Freescale provided for 
drivers—that’s the software that controls various peripheral devices, 
like printers and GPUs—is compatible only with an out-of-date version of 
Linux. And this driver has an unfortunate quirk: It requires any 
application that talks to it to do all floating-point calculations in 
software! That’s far slower than doing the calculations in hardware.

This example nicely illustrates why closed-source products can be so 
frustrating. If we’d used this closed-source driver, we would have 
locked ourselves into an outdated version of Linux and forced other 
applications to do floating-point calculations in software. But if we’d 
gone open source to exploit all the features and benefits of the latest 
Linux version and to allow floating-point calculations done in hardware, 
users would have had to reverse-engineer the GPU to create compatible 
open-source drivers.

img<http://spectrum.ieee.org/img/161MotherboardtopviewBuildupTeardownScottTorborgCrowdSupplyFM7A2260930-1445968001188.jpg> 

Photo: Scott Torborg/Crowd Supply*The Novena’s Heart:*  A view of the 
custom-designed internal circuit boards. Underneath the red heat sink is 
the CPU, and to its immediate right, the FPGA. The white high-speed 
expansion connector at the top right enables users to easily expand and 
modify the hardware’s capabilities.

We decided to stick to our guns and reject the closed-source GPU 
altogether, which meant we would have to render graphics in software.

Unlike Windows and Mac OS, Linux gives you a choice of how your computer 
appears to the user. This appearance is governed by a software utility 
called a desktop window manager. You can select this appearance by 
picking a particular “distribution” of Linux and coupling it with a 
particular window manager. We couldn’t use the popular Ubuntu and RedHat 
distributions because they basically require GPU hardware acceleration, 
which we had rejected. Instead, we used a slightly older-looking but 
more open-source-friendly distribution called Debian. We coupled it with 
a desktop window manager option called Xfce4, which is explicitly 
designed to run well on systems without GPUs and thus is particularly 
good at software rendering.

But that arrangement, we hope, is merely a stopgap. The user community 
behind Novena is trying to create, through reverse engineering, 
open-source drivers that would allow the built-in GPU on the i.MX6 chip 
to render graphics directly. At the moment, we have drivers that can 
accelerate the drawing of 2-D figures on the screen, which makes 
scrolling and window dragging much smoother. We hope eventually to 
figure out enough of the GPU to let us do 3-D graphics with acceleration 
sufficient to produce a user experience much like that of any mainstream 
laptop.

*As the software evolved,*the hardware evolved with it. The most 
extraordinary step we took was to include a field-programmable gate 
array (FPGA), a type of processor chip that can be reconfigured by its 
user to change the chip’s specs and capabilities. Basically, this 
reconfigurability allows the chip to do things in hardware that would 
otherwise have to be done in software.

/img/081LaptopChassisNoScreenBuildupTeardownScottTorborgCrowdSupplyFM7A2306-Edit-1445885708498.jpg 

Photo: Scott Torborg/Crowd Supply

*Novena’s Peek Array:*The brass nuts in the open area at the left 
constitute the Peek Array, a number of points on which users may attach 
expansion boards of their choice. Standard-issue laptops lack this trick 
for making the hardware more hackable.

For instance, if you wanted to accurately control a dozen motors, you’d 
have a lot of trouble doing that in software. Motion control requires 
exquisite real-time control over waveforms, and if you try to get your 
operating system to do that it would constantly be shifting from one 
task to another and back again, adding too much timing jitter. Imagine 
that stutter you see in your Web browser but in a self-driving car or a 
drone: instant wreck. However, it’s a relatively simple matter to create 
hardware that runs the fussy timing and key control loops, and it’s also 
trivial to replicate variations of that hardware again and again in an FPGA.

And at one point, we did in fact want to control a lot of motors. We had 
the wacky notion of mounting Novena in a quadcopter chassis so that our 
laptop could hover and follow us around the office; we figured we’d use 
the FPGA to interface with the requisite motors and sensors. 
Consequently, the FPGA’s input-output connectors were originally 
targeted toward servos and motors.

Cooler heads eventually prevailed. We instead optimized the FPGA for 
data acquisition by adding a bank of local high-speed DDR3 RAM chips, a 
form of high-speed dynamic access memory. This upgrade allowed 
developers to implement a variety of expansion cards, including one 
forsoftware-defined radio 
<http://spectrum.ieee.org/geek-life/hands-on/a-40-softwaredefined-radio>and 
another that worked as a digital sampler, which could allow engineers to 
use our laptop as a portable oscilloscope.

Because we developed the project on a shoestring budget and with no 
solid requirement other than to build the laptop we ourselves would want 
to use, the laptop evolved organically. Instead of designing circuits 
into the motherboard specific to a particular battery or LCD—typical for 
most consumer laptops—we modularized the system. We linked subsystems 
using generic connectors with pin-outs that were merely educated guesses 
as to what users would end up hooking onto those pins.

As a result, the final incarnation of the laptop includes specialized 
adapter boards for the battery pack, LCD, and front-bezel 
<http://www.computerhope.com/jargon/b/bezel.htm>arrangement (the frame 
for the display). The good thing about this modularity is that users can 
adapt the system to meet their own needs. We’re delighted to have 
received reports of users changing out LCDs and building custom battery 
packs. And users can add the keyboard of their choice. We don’t include one.

Aside from the inclusion of an FPGA, our hardware decisions were fairly 
lackluster, even when compared with what comes in a low-end Intel 
laptop. Our i.MX6 SoC contains a quad-core ARM CortexA9 running at 1.2 
gigahertz—a 32-bit processor, which means the system is limited to 4 
gigabytes of RAM. We did, however, choose a fairly decent 1920-by-1080 
display, which is the spec limit for the i.MX6 chip. Our battery life is 
acceptable, at a bit over 6 hours.

/img/201MainboardProcessorandFPGACampaignimagesScottTorborgCrowdSupplyNovena-853-1445887393061.jpg/img/191LaptopeDPadaptorandRAMdetailCampaignimagesScottTorborgCrowdSupplyNovena-1125-1445887322440.jpg/img/221MyriadRFsoftwaredefinedradioexpansionboardBuildupTeardownScottTorborgCrowdSupplyFM7A6229-1445887436697.jpg/img/091LaptopcablesCampaignimagesScottTorborgCrowdSupplyNovena-1114-1445887278613.jpg/img/261OscilloscopeboardtopCampaignimagesScottTorborgCrowdSupplyFM7A7390-1445887531303.jpgPhotos: 
Scott Torborg/Crowd Supply*Soup To Nuts:*At top are the CPU’s red heat 
sink and the FPGA; next is the LCD signal adapter [2nd from top] and the 
battery board [3rd from top]; next, the optional software-defined-radio 
module; then the port farm; at bottom is the digital sampler expansion 
card, which can turn the laptop into an oscilloscope.

We included a few extra features just for the fun of it. We built in an 
accelerometer, although we really don’t know what we’re going to do with 
it. Accelerometers are cheap, and there are a lot of fun things you can 
do with your computer when it’s aware of being tilted, hit, or dropped. 
For instance, you could make your laptopplay a sound clip 
<https://www.youtube.com/watch?v=-ZwximsB55w>of “Goodbye, Cruel World!” 
when it detects that it is in free fall.

Most laptops have one Ethernet port at the most, which means that they 
can act only as endpoints in a network. But we gave Novena two ports to 
let it sit between nodes, filtering and monitoring traffic for security 
purposes. The ports also allow our laptop to function as a Wi-Fi router 
and as an Internet firewall for other wired devices—a handy feature when 
on the road. And although20 hertz is considered the low end 
<https://www.youtube.com/watch?v=4G60hM1W_mk>of human hearing, one of us 
(Huang) has a broader hearing range, so we took the unusual measure of 
extending the analog frequency response of the headphone jack to below 
20 Hz.

These little features are never included on a consumer laptop. But it’s 
these customizations that make the project fun and unique. They add 
cost—but it’s our cost overrun! The fully loaded laptop sold for US 
$2,000 during the crowd campaign. So far, we’ve sold about 500.

*Initially, we didn’t plan on*going as far as building a mass-producible 
case. In fact, we made our first case by hand out of leather, bound like 
a book. The warm reception it got on social media led us to attempt a 
crowdfunding campaign viaCrowd Supply <http://www.crowdsupply.com/>, a 
site that takes the idea of Kickstarter and turbocharges it with a Web 
store and logistics services.

One thing we learned in that brush with the mainstream consumer was that 
most people were not prepared for the experience we were delivering. Our 
laptop won’t run Windows or Mac OS, nor is it particularly fast or thin. 
So in order to differentiate our laptop and make it more attractive to 
true techies, we decided to add some of the things that developers 
prize. These included mounting bosses—an internal array of metal 
nuts—which we call the Peek Array (after Nadya Peek, of FabLab fame 
<http://fab.cba.mit.edu/classes/S62.12/people/nadya.peek/>).

Typical laptops are unhackable because there’s no place to put 
other...stuff. If you can find the empty space in a laptop, you’d have 
to glue your expansion board in place or drill a hole through the case 
to mount your custom hardware. Not so with the Peek Array! Its dozens of 
threaded nuts allow users to screw all manner of small project boards 
into the laptop case. Want to add a pulse oximeter to Novena so you can 
measure thelevel of oxygen in the blood 
<http://www.bunniestudios.com/blog/?p=3472>running through the 
capillaries of your finger? Or maybe a barometer so you can monitor your 
airliner’s cabin pressure? With just a few screws you can mount your 
customization inside Novena’s laptop case.

/img/392BunnieArticleImagesScottTorborgCrowdSupplyFM7A2344-1445885285362.jpg 

Photo: Scott Torborg/Crowd Supply*Andrew “bunnie” Huang*visits the 
Portland, Ore., workshop of collaborator Kurt Mottweiler, who is working 
on the Heirloom version of the Novena laptop. This special configuration 
features a hand-crafted wood-and-aluminum case.

We also designed the case to open easily under the impetus of an air 
spring, like the ones used to raise the seat on ergonomic office chairs. 
With the flick of a switch, the lid (with the screen) opens 
automatically. We preferred this to a conventional clamshell design on 
the theory that any laptop that exposes its guts to the user will 
particularly appeal to users prepared to hack the guts. (People who fear 
naked circuit boards shouldn’t buy our laptop anyway!)

The case is designed to serve through generations of electronics 
hardware. For instance, to hold the liquid-crystal display in place we 
used computer numerically controlled (CNC) machining to make an aluminum 
bezel. Anyone with access to an entry-level machine shop can fabricate a 
custom bezel to accommodate a different LCD, as well as mount additional 
sensors (such as a camera or a microphone) or additional buttons and knobs.

By putting most of the ports on a single edge, which we call the Port 
Farm, we made it easy to replace the panel covering it. That way the 
user can keep the case itself even as the motherboard and the Port Farm 
evolve.

We took into account the total costs of manufacturing tooling as well. 
For instance, though injection-molded plastic is very cheap on a 
per-unit basis, the steel tools that produce it are not. You need an 
oil-cooled block weighing about a ton, capable of handling pressures 
found at the bottom of the Mariana Trench, machined internally to a 
tolerance less than the width of a human hair, with a moving clockwork 
of dozens of ejector pins, sliders, lifters, and parting surfaces 
separating and coming back together again smoothly over thousands of 
cycles. Itcan easily cost $250,000 
<http://medicaldesign.com/contract-manufacturing/changing-face-injection-molding>, 
which is why the injection molding process can pay for itself only in 
very large manufacturing runs. We instead used a combination of CNC 
aluminum, optimized plastic design, and family molds (whose various 
parts each form a different aspect of a given product). We needed just 
10 machine tools to produce the case, for an up-front investment of 
about $50,000.

As we write this, we’ve shipped all of our standard laptop and desktop 
units to our crowdfunding campaign backers. We’ve marshaled nearly a 
thousand components from dozens of vendors, from Shenzhen, China, to 
Fremont, Calif.

Thanks to the magic of crowdfunding and a slowdown of Moore’s Law, a 
two-person team was able to have the funds and the time to implement an 
everyday-use laptop. Furthermore, this laptop’s schematics, circuit 
board layouts, mechanical design files, kernel, drivers, and application 
programs are all open source and available for anyone to download.

Such transparency is unprecedented. We hope it will encourage other 
engineers to follow in our footsteps and help users reclaim their 
technological independence.

/This article originally appeared in print as “A Laptop With No Secrets.”/


    About the Author

Andrew Huang <http://www.bunniestudios.com/blog/?tag=novena>andSean 
Cross <https://twitter.com/xobs>are self-employed American computer 
scientists living in Singapore.Huang wrote on the death of Moore's Law 
<http://spectrum.ieee.org/semiconductors/design/the-death-of-moores-law-will-spur-innovation>for 
our April issue.

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