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This article mainly introduces "What is Cortex, ARMv8, arm architecture, ARM instruction set, soc", in daily operation, I believe many people in what is Cortex, ARMv8, arm architecture, ARM instruction set, soc problems have doubts, small series consulted all kinds of information, sorted out simple and easy to use operation methods, hope to answer "What is Cortex, ARMv8, arm architecture, ARM instruction set, soc" doubts help! Next, please follow the small series to learn together!

ARM Holdings

ARM was originally an acronym for Advanced RISC Machines. But he wasn't originally called that name. Take a look at ARM's growth history.

In 1978, Hermann Hauser, an Austrian Ph.D. physicist, and his friend Chris Curry, a British engineer, founded a company called CPU. The full name of this CPU company is Cambridge Processor Unit, which literally means "Cambridge Processor Unit."

After the establishment of CPU company, mainly engaged in electronic equipment design and manufacturing business. The first order they received was for a microcontroller system for gambling machines.

This microcontroller system was developed and called Acorn System 1.

They were called Acorn because they wanted to be ahead of Apple in the phone book.

After Acorn System 1, they went on to develop Systems 2, 3, 4, and a box computer for consumers, the Acorn Atom.

In 1981, the company had a rare opportunity. The BBC wanted to broadcast a programme to improve computer popularity throughout the UK. They wanted Acorn to produce a computer to go with it.

However, they found that the hardware design of their products did not meet the needs. At that time, the trend of CPU development was changing from 8 bits to 16 bits. Acorn doesn't have the right chip to use.

So they went to Intel, which was at its peak, and asked for some design information and samples of the 80286 processor. However, Intel ruthlessly rejected them.

Acorn, a battered company, decided in a fit of anger to do it itself and make its own chips. (How familiar!)

So Acorn researchers found research from the University of California, Berkeley, on a new type of processor--a simplified instruction set--that met their design requirements.

After years of hard work, computer scientists Sophie Wilson and Steve Furber from Cambridge University finally completed the design of the microprocessor. The former is responsible for instruction set development, while the latter is responsible for chip design.

For this chip, Acorn named it Acorn RISC Machine.

This is where the three letters **"ARM"** come from.

After ARM1, Acorn released several series, such as ARM2 and ARM3.

In 1990, Acorn set up a company called ARM to work with Apple.

Note that ARM here is the company name, not the chip name. ARM is also spelled Advanced RISC Machines.

Previous Chip Name: Acorn RISC Machine Current Company Name: Advanced RISC Machines

In the 1990s, ARM 32-bit RISC(Reduced lnstruction Set Computer) processor expanded to the international scope, occupying the leading position in the field of embedded system application with low power consumption, low cost and high function.

ARM does not make or sell chips, it sells only licensing of chip skills.

Formal formulation of this policy, let ARM company get rid of cash flow problems, can devote themselves to chip research and development.

On April 17, 1998, ARM Holdings, a fast-growing company, listed on both the London Stock Exchange and NASDAQ.

In 2007, the epoch-making product-iPhone was introduced. The first generation of iPhone, it is the use of ARM design, Samsung manufacturing chips.

In 2008, Google launched Android, also based on the ARM instruction set. At this point, smart phones have entered a stage of rapid development, and ARM has thus established its dominance in the smart phone market.

July 18, 2016 news, Japan Softbank for 23.4 billion pounds (about 31 billion US dollars) to buy British chip design company ARM.

On September 14,2020, NVIDIA officially announced that it would acquire ARM from SoftBank for $40 billion. Under the agreement, Nvidia will pay SoftBank $21.5 billion worth of Nvidia stock and $12 billion in cash.

At present, the acquisition has been opposed by a number of Silicon Valley technology giants, including Intel, Qualcomm and Tesla, who believe the deal is bad for the industry, and regulators in China and the European Union may also oppose the acquisition.

Just wait and see!

ARM kernel and architecture

Any ARM chip consists of two main parts: the ARM core and peripherals.

ARM core

ARM kernel: includes register set, instruction set, bus, memory mapping rules, interrupt logic and debug components. The kernel is designed by ARM and sold under license to several chip manufacturers (ARM does not make chips itself). For example, Cortex A8 and A9 designed for high speed are ARMv7a architecture;Cortex M3 and M4 are ARMv7m architecture; the former is processor (core), and the latter is instruction set architecture (also referred to as architecture).

Peripherals include timer, A/D converter, memory, i2c, UART, SPI, ROM... And so on, it is completely designed by each chip manufacturer and matched with ARM core. Different chip manufacturers have different peripherals, so they constitute a large number and specifications of ARM chip industry.

ARM ISA

Instruction Set Architecture (ISA) is the most important part of the processor architecture.

Instruction set can be said to be the soul of CPU design, is to open the CPU Pandora's Box spell, to use CPU, we can only operate CPU through these instructions.

For a 32-bit cpu, these instructions are sequences of 32-bit 01s, different values represent different machine instructions, and cpu hardware can perfectly parse and execute these instructions, such as addressing, arithmetic, exception handling, and so on.

When we play Glory of Kings on our mobile phones, we must know that every move we make is actually translated into a series of machine instructions.

From the birth of ARMv1 architecture in 1985 to 2011, ARM architecture has evolved to the eighth generation ARMv8.

The Cortex-A32/35/53/57/72/73/77/78 are based on ARMv8 architecture, ARM's first processor architecture to support 64-bit instruction sets.

Processor and Instruction Set Architecture Prior to ARM11

Before ARM11 chips, the architecture relationship corresponding to each chip is as follows:

Post ARM11 Processor and Instruction Set Architecture

After the ARM11 chip, that is, starting with the ARMv7 architecture, the naming of ARM has changed.

The new processor family, renamed Cortex, is divided into three families: Cortex-A, Cortex-R, and Cortex-M.

Coincidentally, it was those three letters A, R, and M again.

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Cortex-A Series (A: Application)

Designed for growing consumer entertainment and wireless products for applications with high computing requirements, running rich operating systems and providing interactive media and graphics experiences, such as smartphones, tablets, automotive entertainment systems, digital TVs, smart books, e-readers, home networks, home gateways and a variety of other products.

Cortex-R Series (R: Real-time)

For system applications that require real-time operation, deep embedded real-time applications such as automotive braking systems, powertrain solutions, mass storage controllers, etc.

Cortex-M Series (M: Microcontroller)

The family is geared towards the microcontroller sector and is aimed at cost and power sensitive applications such as smart measurement, human interface devices, automotive and industrial control systems, household appliances, consumer products and medical devices.

Cortex-SC Series (SC: SecurCore)

In fact, in addition to the above three series, there is also a main security Cortex-SC series (SC: SecurCore), mainly used for government security chips.

ARM's product ladder

The ARM11 family includes the ARM11MPCore processor, ARM1176 processor, ARM1156 processor, and ARM1136 processor, which are based on the ARMv6 architecture.

ARM Cortex-A5 processor, Cortex-A7 processor, Cortex-A8 processor, Cortex-A9 processor, Cortex-A15 processor belong to Cortex-A series, based on ARMv7-A architecture.

The Cortex-A53 and Cortex-A57 processors belong to the Cortex-A50 family and adopt the 64-bit ARMv8 architecture for the first time.

ARM recently released a new CPU architecture Cortex-A78 based on the ARMv8.2 instruction set.

What is SOC?

The full name of SoC is System-on-a-Chip, which means "putting the system on one chip" in Chinese.

SoC integrates many of the most critical components on mobile phones, such as CPU, GPU, memory, that is to say, although it exists on the motherboard as a chip, it is composed of many components packaged inside.

For example, what we usually call Qualcomm 801, Kirin 950. Samsung's exynos 4412, A6, etc. are just the general name of the system component package (SoC). However, the contents of each package are different, and the reasons are different.

The classic ARM system-on-chip or so-called SoC contains many components, only some of which originate directly from ARM. First, the core itself is usually deeply embedded within the device and is usually not directly visible within the device, while the debug port is usually the only exposed part connected to the core itself, with some glue logic, such as clock and reset integrated circuits.

Since the ARM core has only two interrupt inputs, the most common peripheral is some kind of interrupt controller, which is internal to the peripheral and the components are connected to each other through an on-chip interconnect bus architecture, which is standard AMBA interconnect for most ARM-based devices.

AMBA specifies two buses, a high-performance system bus called AXI, and a low-power peripheral bus called APB, APB is usually used to connect all peripherals, AXI is used for memory and other high-speed devices, most devices have a certain amount of on-chip storage and interface to connect peripheral memory devices, but note that the external connection to the device is not the AMBA bus, which is only used inside the device and is not exposed.

Exynos 4412 SCP

Let's take Exynos(Orion) 4412 SCP as an example to explain these concepts.

Samsung's Exynos 4412 SCP is a Cortex-A9-based SOC;

As shown in the figure below, Exynos 4412 contains 4 Cortex-A9 processors (cores);

Cortex-A9 is based on ARMv7-A architecture (instruction set).

As can be seen from the above figure, the exynos 4412 contains four Cortex-A9 cores and a large number of peripheral controllers: DRAM Controller, SROM Controller, Camera IF, JPEG, GPS/GLONASS, Power Management, USB Host, I2C, UART, SPI, etc.

Samsung and the same other major manufacturers and arm cooperation will usually put its CPU and all kinds of peripheral IP together, and then take their own drawings to flow out, the production is also a square, there are a lot of pins below, this thing not only contains the CPU, but also contains other controllers, this thing is called SOC(system on chip).

As shown in the figure below, it is Samsung's final Exynos 4412. Of course, this soc alone cannot run Android, and a large number of peripherals are needed to form a complete system, but most of the most complex hardware modules have been integrated into this soc.

At present, what major manufacturers do is to buy ARM authorization, get the source code of ARM processor, and then make some peripheral IP(or buy or design it yourself), and then form a SOC and go to the stream. Different SOCs have different architectures (that is, how CPU and IP are connected, some with bus as the core, some with DDR as the core).

HiSilicon is an SOC architecture with independent property rights. However, no matter how much trouble any manufacturer has, they have not moved the CPU, and the ARM core is well there, that is, the central processor.

ARM Licensing

How to understand ARM licensing?

For example, we manufacture cars, ARM has the most advanced 'engine' design scheme, but he does not 'produce engine', but licenses the design scheme to major' automobile manufacturers 'to produce, and the money earned continues to develop more advanced' engine'.

ARM authorization is divided into ARM architecture authorization, IP core authorization, and use level authorization.

If a company wants to use ARM's kernel to make its own processor, such as ST, Apple, Samsung, TI, Qualcomm, Huawei, etc., it must purchase different levels of authorization under its architecture from ARM, and purchase corresponding levels of authorization according to the use needs.

There are three ways to authorize architecture: architecture-level authorization, kernel-level authorization (ip core authorization), and usage-level authorization.

1. Architecture level authorization means that ARM architecture can be greatly modified, and even ARM instruction set can be expanded or reduced. Apple is a good example. Based on ARMv7-A architecture, Apple has extended its own swift architecture.

2. Kernel-level authorization means that you can take a kernel as the basis and then add your own peripherals, such as USART, GPIO, SPI, ADC, etc., and finally form your own MCU. There are many such companies, such as Samsung and TI.

3. Using hierarchical authorization, to use a processor, obtaining authorization to use the hierarchy is the most basic, which means that you can only use the defined ip provided by others to embed in your design, you cannot change others 'ip, and you cannot use others' ip to create your own packaging products based on the ip.

Therefore, if Huawei obtains architecture authorization and ip core authorization respectively, it means that it can create its own kernel architecture based on ARM instruction set according to needs, and can add various on-chip peripherals such as communication interface, display control interface, GPIO, etc., so as to produce its own "processor chip."

In fact, just like I wrote an article, I told A that you can use it after modification, that is, architecture level authorization, I told B that you can quote my article in your article, that is, kernel-level authorization, I told C that you can only forward my article, can not change, can not add embellishment, that is, use hierarchical authorization.

At this point, the study of "what is Cortex, ARMv8, arm architecture, ARM instruction set, soc" is over, hoping to solve everyone's doubts. Theory and practice can better match to help everyone learn, go and try it! If you want to continue learning more relevant knowledge, please continue to pay attention to the website, Xiaobian will continue to strive to bring more practical articles for everyone!

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