ECE150 (Mobile Embedded Systems) > Application Processors Part 2 > Flashcards

Application Processors Part 2 Flashcards

(23 cards)

Study These Flashcards
1
Q

What are the ARMv7 Cortex-A series features?

A
  • Thumb and Jazelle
  • Vector floating point architecture
  • Single instruction multiple data
  • big.Little System
  • Dynamic voltage and frequency scaling
  • TrustZone
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2
Q

What are the two instruction sets?

A
  • ARM : standard 32-bit instruction set

- Thumb : 16-bit compressed form

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3
Q

What are the important features of THUMB mode?

A
  • Only low registers r0 to r7 are fully accessible
  • Only branch instruction can be conditionally executed
  • Barrel shift operations are separate instructions
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4
Q

What is the interworking of Thumb?

A
  • To call a thumb routine from an ARM routine the core has to change state : T bit in CPSR
  • BX and BLX instruction can be used for the switch.
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5
Q

What is Jazelle?

A

Since Java byte code is executed in hardware, the Java byte code is the result of the compilation of a Java program. Recognized Java byte codes are converted into a string of one or more native ARM instructions

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6
Q

What is Vector Floating Point (VFP)

A

?It is a coprocessor
- CPD() cp, opcode1, Cd, Cn, Cm
– Cp represents coprocessor number between p0 to p15
– Opcode field describes coprocessor operation
– Cd, Cn, Cm coprocessor registers
Coprocessor register transfer and memory transfer instructions are distinct from the main ARM processor

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7
Q

What is VFP registers?

A

32 bit wide VFP register file organized as four register banks, each including 8 registers.
- The first bank is used to hold scalar operands whereas the remaining three banks vector operands

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8
Q

What is VFP operation

A
  • A vector operand may refer to 2 to 8 registers from the same bank
  • The vector length is given in a specific field of a control register
  • The register numbers given in the instruction specify the first registers that contain the first operands and specify the first destination register
  • Each successive element of the vector is taken by incrementing appropriately the register numbers
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9
Q

What is SIMD?

A

Single instruction multiple data.

Single instruction operates on multiple data elements

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10
Q

What is parallelism in SIMD processing?

A
  • Signal instruction operates on multiple data elements
  • Multiple processing elements
  • Time-space duality
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11
Q

What is the time space duality?

A

Array processor: Instruction operates on multiple data elements at the same time
Vector processor: Instruction operates on multiple data elements in consecutive time steps

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12
Q

What is big.Little processing?

A
  • Aims primary at power reduction
  • Workload of smartphones and tablets is dynamically changing
    • High intensity tasks: Games, Video
    • Low intensity tasks: Audio, email, news paper
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13
Q

Advantage of big.Little processing?

A
  • Uses the right processor for the right job
  • Up to 70% energy savings on common workloads
  • Flexible and transparent to apps
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14
Q

What are the three clusters of big.Little?

A
  • 2.5GHz eXtreme performance
  • 2.0GHz bestperf/power balance
  • 1.4GHz Best Power Efficiency
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15
Q

What is DVFS?

A

Dynamic Voltage and Frequency Scaling
- Since energy is proportional to f^2, DVFS can potentially provide significant energy savings through frequency and voltage scaling

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16
Q

Energy with and without DVFS

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A

Without DVFS E1 = K20F^2

With DVFS E2=K20(F/2)^2

17
Q

What are the features of communication chips?

Study These Flashcards
A
  • Less management frame frequency
  • Clock gating
  • Power Islanding
  • Fast napping
  • Fast-scan-and-restore from memory.
18
Q

What type of power management is in smartphones?

Study These Flashcards
A

DC/DC converter provides large capacity power

LDO (Low Drop Out) provides small capacity power

19
Q

What is variable voltage and frequency processors?

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A

Modern processors operate at multiple frequency levels.

20
Q

What is TrustZone?

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A
  • Deals with security features in many digital electronic devices such as set-top boxes, payment and network equipment
  • Software application built directly into the hard drive
  • Ensures that security is an intrinsic feature at the heart of any device
21
Q

How does TrustZone works?

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A
  • Memory Management Unit (MMU) and Caches- uses tables to determine which level a particular level of memory exists in
  • Secure Mode
  • Non-Secure Mode
22
Q

What is in Secure Mode?

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A
  • Ensures vital information is not intercepted by a third party
  • Encryption/decryption according to the Advanced Encryption Standard
23
Q

What is Non-secure Mode?

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A
  • Non-secure mode allows more access to less protected information
ECE150 (Mobile Embedded Systems)
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