New Scientist - USA (2021-03-06)

14 | New Scientist | 6 March 2021

News

TESTING new computer chips for

security and reliability often takes

longer than designing them. A

new method for modelling them

virtually and testing them with

programs conventionally used

for software instead of hardware

could reduce development time.

Current hardware testing either

randomly probes a chip to find

flaws or seeks to formally test

every single possible input and

output on each computer chip.

The first approach can easily

miss problems and the second

quickly becomes infeasible for

all but the simplest designs.

Either way, testing can take

months, but a single flaw in a piece

of hardware can make computers

unreliable or vulnerable to

hacks and, unlike a software flaw,

cannot be fixed with an update

after shipping. Now, a team of

researchers at the University

of Michigan, Google and Virginia

Tech has sped up the testing

process by simulating computer

chips and using advanced software

testing tools to analyse them.

Chip designs were translated into

code and given a layer of software

on top to make them operate as

they would in real-world use.

Testing chips virtually enables

engineers to use an approach

called fuzzing, which watches

for unexpected results or crashes

that can then be examined and

fixed. The problematic inputs

that caused them are mutated

and adapted to probe for

similar problems in the rest

of the chip. This covers ground

more productively than purely

random tests.

One problem that the team had

to overcome is that chips and

code work in very different ways.

Chips churn through a constant

stream of inputs and outputs,

conducting thousands of simple

operations to achieve a larger

task, whereas software tests often

involve submitting single inputs

like text or a file and observing

the output. The team had to adapt

software fuzzers to run over time

rather than fire off a single input

and wait for the response.

“We had to trick these software

fuzzers into interpreting inputs

differently than they do in the

software space. In a sense, what

we were doing is we were taking

inputs in a single dimension and

extracting multiple dimensions,”

says Timothy Trippel at the

University of Michigan.

This method reduced the time

taken to test a chip design by two

orders of magnitude – a chip that

would usually take 100 days to test

can be analysed in a single day

(arxiv.org/abs/2102.02308).

The team later used the

approach on an OpenTitan

chip designed by Google.

Within an hour, it had covered

88 per cent of the lines of code

that made up the software model

among three of the sections,

and 65 per cent of the fourth.

Faster hardware testing

could bring the next generation

of chips to consumers faster,

and in a more reliable and

secure state, says the team.

Rob Hierons at the University

of Sheffield, UK, agrees that

testing hardware before

production would be desirable,

faster and cheaper, but cautions

that no approach could ever

guarantee a design is free of flaws.

“Fuzzing adds some direction

to random [testing], but in the end

it will often be limited,” he says. ❚

Matthew Sparkes

Animal behaviour

Ship noise affects

dolphins that help

humans catch fish

SOME dolphins help humans catch

fish – but perhaps not for much

longer. An uptick in noise pollution

from ships is changing the way

these dolphins communicate. It is

possible that this may reduce the

dolphins’ ability to coordinate

their behaviour to their – and the

humans’ – advantage.

Near Laguna in southern Brazil,

a group of Lahille’s bottlenose

dolphins (Tursiops truncatus

gephyreus) works together to drive

schools of fish like mullet into the

shallow water where fishers cast

handheld nets, catching fish and

breaking up the schools. While the

water is murky, the dolphins are

believed to take advantage of the

chaos, snatching up disorientated

fish missed by the nets.

The relationship is at least

a century old, but it might be

imperilled by the increasing noise

made by ships that pass nearby.

Bianca Romeu at the Federal

University of Santa Catarina, Brazil,

and her colleagues found that,

during noisier periods, the dolphins

produced fewer whistles and

increased their pitch (Animal

Conservation, doi. org/fxqp).

In other words, the dolphins

were communicating differently

when boats were around, which

could affect the way they get

organised to forage with the

fishers, says Romeu.

“Probably the noise isn’t

interrupting the activities, but it

can disturb them, can change their

behaviour,” says Romeu. She adds

that it may make the dolphins worse

at working together to drive the fish

towards the fishers.

The problem isn’t easily solved,

but Romeu says that authorities

could perhaps consider introducing

rules to limit how many boats can

pass nearby at any one time. ❚

Joshua Rapp Learn

Technology

Safer computer chips, fast

Virtual testing slashes the time to make and test computer components

The dolphins near Laguna,

Brazil, have been helping

people fish for a century

“ This could test chips faster

and cheaper, but no

method can guarantee

a design is free of flaws”

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