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88-616: RISC-V (pronounced "risk-five") is an open standard instruction set architecture (ISA) based on established reduced instruction set computer (RISC) principles. The project began in 2010 at the University of California, Berkeley , transferred to the RISC-V Foundation in 2015, and on to RISC-V International, a Swiss non-profit entity, in November 2019. Like several other RISC ISAs, e.g. Amber (ARMv2) or OpenRISC , RISC-V

176-514: A "free software and open standards law." The decree includes the requirement that the Venezuelan public sector must use free software based on open standards, and includes a definition of open standard: Non-disclosure agreement A non-disclosure agreement ( NDA ), also known as a confidentiality agreement ( CA ), confidential disclosure agreement ( CDA ), proprietary information agreement ( PIA ), or secrecy agreement ( SA ),

264-639: A CPU's complexity and costs slightly less because it reads all sizes of words in the same order. For example, the RISC-V instruction set decodes starting at the lowest-addressed byte of the instruction. Big-endian and bi-endian variants were defined for support of legacy code bases that assume big-endianness. The privileged ISA defines bits in the mstatus and mstatush registers that indicate and, optionally, control whether M-mode, S-mode, and U-mode memory accesses other than instruction fetches are little-endian or big-endian; those bits may be read-only, in which case

352-420: A combinatorial explosion in possible ISA choices. Profiles specify a much smaller common set of ISA choices that capture the most value for most users, and which thereby enable the software community to focus resources on building a rich software ecosystem. The platform specification defines a set of platforms that specify requirements for interoperability between software and hardware. The Platform Policy defines

440-681: A common patent policy under the banner of the WSC . However, the ITU-T definition should not necessarily be considered also applicable in ITU-R, ISO and IEC contexts, since the Common Patent Policy does not make any reference to "open standards" but rather only to "standards." In section 7 of its RFC 2026, the IETF classifies specifications that have been developed in a manner similar to that of

528-586: A contract subject to the rules of contractual interpretation which generally apply in the English courts. NDAs are often used as a condition of a financial settlement in an attempt to silence whistleblowing employees from making public the misdeeds of their former employers. There is law, the Public Interest Disclosure Act 1998 , which allows "protected disclosure" despite the existence of an NDA, although employers sometimes intimidate

616-402: A data format which is made public, is thoroughly documented and neutral with regard to the technological tools needed to peruse the same data. The E-Government Interoperability Framework (e-GIF) defines open standard as royalty-free according to the following text: While a universally agreed definition of "open standards" is unlikely to be resolved in the near future, the e-GIF accepts that

704-606: A definition of "open standards" needs to recognise a continuum that ranges from closed to open, and encompasses varying degrees of "openness." To guide readers in this respect, the e-GIF endorses "open standards" that exhibit the following properties: The e-GIF performs the same function in e-government as the Road Code does on the highways. Driving would be excessively costly, inefficient, and ineffective if road rules had to be agreed each time one vehicle encountered another. The Portuguese Open Standards Law, adopted in 2011, demands

792-535: A definition of open standards, which also is used in pan-European software development projects. It states: The French Parliament approved a definition of "open standard" in its "Law for Confidence in the Digital Economy." The definition is (Article 4): A clear royalty-free stance and far reaching requirements case is the one for India's Government 4.1 Mandatory Characteristics An Identified Standard will qualify as an "Open Standard", if it meets

880-474: A description of a 128-bit flat address space variant, as an extrapolation of 32- and 64-bit variants, but the 128-bit ISA remains "not frozen" intentionally, because as of 2023, there is still little practical experience with such large memory systems. Unlike other academic designs which are typically optimized only for simplicity of exposition, the designers intended that the RISC-V instruction set be usable for practical computers. As of June 2019, version 2.2 of

968-494: A fixed length of 32-bit naturally aligned instructions, and the ISA supports variable length extensions where each instruction can be any number of 16-bit parcels in length. Extensions support small embedded systems , personal computers , supercomputers with vector processors, and warehouse-scale parallel computers . The instruction set specification defines 32-bit and 64-bit address space variants. The specification includes

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1056-605: A full, irrevocable and irreversible way to the Portuguese State; e) There are no restrictions to its implementation. A Law passed by the Spanish Parliament requires that all electronic services provided by the Spanish public administration must be based on open standards. It defines an open standard as royalty-free, according to the following definition (ANEXO Definiciones k): An open standard fulfills

1144-426: A given microarchitecture . The requirements of a large base of contributors is part of the reason why RISC-V was engineered to address many possible uses. The designers' primary assertion is that the instruction set is the key interface in a computer as it is situated at the interface between the hardware and the software. If a good instruction set were open and available for use by all, then it can dramatically reduce

1232-418: A one-way NDA) involves two parties where only one party (i.e., the disclosing party) anticipates disclosing certain information to the other party (i.e., the receiving party) and requires that the information be protected from further disclosure for some reason (e.g., maintaining the secrecy necessary to satisfy patent laws or legal protection for trade secrets, limiting disclosure of information prior to issuing

1320-406: A press release for a major announcement, or simply ensuring that a receiving party does not use or disclose information without compensating the disclosing party). A bilateral NDA (sometimes referred to as a mutual NDA, MNDA, or a two-way NDA) involves two parties where both parties anticipate disclosing information to one another that each intends to protect from further disclosure. This type of NDA

1408-671: A product that may last many years. To address this issue, the RISC-V Foundation was formed in 2015 to own, maintain, and publish intellectual property related to RISC-V's definition. The original authors and owners have surrendered their rights to the foundation. The foundation is led by CEO Calista Redmond , who took on the role in 2019 after leading open infrastructure projects at IBM . The founding members of RISC-V were: Andes, Antmicro, Bluespec, CEVA, Codasip, Cortus, Esperanto, Espressif, ETH Zurich, Google, IBM, ICT, IIT Madras, Lattice, lowRISC, Microchip, MIT (Csail), Qualcomm, Rambus, Rumble, SiFive, Syntacore and Technolution. In November 2019,

1496-492: A public-domain instruction set and are still supported by the GNU Compiler Collection (GCC), a popular free-software compiler. Three open-source cores exist for this ISA, but were never manufactured. OpenRISC , OpenPOWER , and OpenSPARC / LEON cores are offered, by a number of vendors, and have mainline GCC and Linux kernel support. Krste Asanović at the University of California, Berkeley , had

1584-441: A receiving party could later become a disclosing party or vice versa, which is not an entirely uncommon occurrence. A multilateral NDA involves three or more parties where at least one of the parties anticipates disclosing information to the other parties and requires that the information be protected from further disclosure. This type of NDA eliminates the need for separate unilateral or bilateral NDAs between only two parties. E.g.,

1672-532: A research requirement for an open-source computer system, and in 2010, he decided to develop and publish one in a "short, three-month project over the summer" with several of his graduate students. The plan was to aid both academic and industrial users. David Patterson at Berkeley joined the collaboration as he was the originator of the Berkeley RISC, and the RISC-V is the eponymous fifth generation of his long series of cooperative RISC-based research projects at

1760-463: A series of academic computer-design projects, especially Berkeley RISC . RISC-V was originated in part to aid all such projects. To build a large, continuing community of users and thereby accumulate designs and software, the RISC-V ISA designers intentionally support a wide variety of practical use cases: compact, performance, and low-power real-world implementations without over-architecting for

1848-598: A set of principles which have contributed to the exponential growth of the Internet and related technologies. The "OpenStand Principles" define open standards and establish the building blocks for innovation. Standards developed using the OpenStand principles are developed through an open, participatory process, support interoperability, foster global competition, are voluntarily adopted on a global level and serve as building blocks for products and services targeted to meet

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1936-447: A simplified general-purpose computer, with full software support, including a general-purpose compiler. The standard extensions are specified to work with all of the standard bases, and with each other without conflict. Many RISC-V computers might implement the compressed instructions extension to reduce power consumption, code size, and memory use. There are also future plans to support hypervisors and virtualization . Together with

2024-471: A single multiparty NDA entered into by three parties who each intend to disclose information to the other two parties could be used in place of three separate bilateral NDAs between the first and second parties, second and third parties, and third and first parties. A multilateral NDA can be advantageous because the parties involved review, execute, and implement just one agreement. This advantage can be offset by more complex negotiations that may be required for

2112-411: A written contract between the parties. It is a contract through which the parties agree not to disclose any information covered by the agreement. An NDA creates a confidential relationship between the parties, typically to protect any type of confidential and proprietary information or trade secrets . As such, an NDA protects non-public business information. Like all contracts, they cannot be enforced if

2200-462: Is a legal contract or part of a contract between at least two parties that outlines confidential material, knowledge, or information that the parties wish to share with one another for certain purposes, but wish to restrict access to. Doctor–patient confidentiality (physician–patient privilege), attorney–client privilege , priest–penitent privilege and bank–client confidentiality agreements are examples of NDAs, which are often not enshrined in

2288-446: Is a load–store architecture . Its floating-point instructions use IEEE 754 floating-point. Notable features of the RISC-V ISA include: instruction bit field locations chosen to simplify the use of multiplexers in a CPU, a design that is architecturally neutral, and a fixed location for the sign bit of immediate values to speed up sign extension . The instruction set is designed for a wide range of uses. The base instruction set has

2376-409: Is a load–store architecture : instructions address only registers, with load and store instructions conveying data to and from memory. Most load and store instructions include a 12-bit offset and two register identifiers. One register is the base register. The other register is the destination (for a load) or the source (for a store). The offset is added to a base register to get the address. Forming

2464-536: Is a zero register , and the remainder are general-purpose registers. A store to the zero register has no effect, and a read always provides 0. Using the zero register as a placeholder makes for a simpler instruction set. Control and status registers exist, but user-mode programs can access only those used for performance measurement and floating-point management. No instructions exist to save and restore multiple registers. Those were thought to be needless, too complex, and perhaps too slow. Like many RISC designs, RISC-V

2552-451: Is absent, and 1.0 if all of a version number is absent. Thus RV64IMAFD may be written as RV64I1p0M1p0A1p0F1p0D1p0 or more simply as RV64I1M1A1F1D1 . Underscores may be used between extensions for readability, for example RV32I2_M2_A2 . The base, extended integer & floating-point calculations, with synchronization primitives for multi-core computing, are considered to be necessary for general-purpose computing, and thus we have

2640-414: Is addressed as 8-bit bytes, with instructions being in little-endian order, and with data being in the byte order defined by the execution environment interface in which code is running. Words, up to the register size, can be accessed with the load and store instructions. RISC-V was originally specified as little-endian to resemble other familiar, successful computers, for example, x86 . This also reduces

2728-455: Is common for businesses considering some kind of joint venture or merger. When presented with a unilateral NDA, some parties may insist upon a bilateral NDA, even though they anticipate that only one of the parties will disclose information under the NDA. This approach is intended to incentivize the drafter to make the provisions in the NDA more "fair and balanced" by introducing the possibility that

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2816-714: Is determined by the market. The ITU-T is a standards development organization (SDO) that is one of the three sectors of the International Telecommunication Union (a specialized agency of the United Nations ). The ITU-T has a Telecommunication Standardization Bureau director's Ad Hoc group on IPR that produced the following definition in March 2005, which the ITU-T as a whole has endorsed for its purposes since November 2005: The ITU-T , ITU-R , ISO , and IEC have harmonized on

2904-557: Is here meant in the sense of fulfilling the following requirements: The Network Centric Operations Industry Consortium (NCOIC) defines open standard as the following: Specifications for hardware and/or software that are publicly available implying that multiple vendors can compete directly based on the features and performance of their products. It also implies that the existing open system can be removed and replaced with that of another vendor with minimal effort and without major interruption. The Danish government has attempted to make

2992-533: Is offered under royalty-free open-source licenses . The documents defining the RISC-V instruction set architecture (ISA) are offered under a Creative Commons license or a BSD License . Mainline support for RISC-V was added to the Linux 5.17 kernel, in 2022, along with its toolchain . In July 2023, RISC-V, in its 64-bit variant called riscv64, was included as an official architecture of Linux distribution Debian , in its unstable version. The goal of this project

3080-506: Is then published in the form of RFC 6852 in January 2013. The European Union defined the term for use within its European Interoperability Framework for Pan-European eGovernment Services, Version 1.0 although it does not claim to be a universal definition for all European Union use and documentation. To reach interoperability in the context of pan-European eGovernment services, guidance needs to focus on open standards. The word "open"

3168-759: The GSM phones (adopted as a government standard), Open Group which promotes UNIX , and the Internet Engineering Task Force (IETF) which created the first standards of SMTP and TCP/IP. Buyers tend to prefer open standards which they believe offer them cheaper products and more choice for access due to network effects and increased competition between vendors. Open standards which specify formats are sometimes referred to as open formats . Many specifications that are sometimes referred to as standards are proprietary, and only available (if they can be obtained at all) under restrictive contract terms from

3256-607: The New Zealand , South African and the Venezuelan governments. On the standard organisation side, the World Wide Web Consortium (W3C) ensures that its specifications can be implemented on a royalty-free basis. Many definitions of the term standard permit patent holders to impose " reasonable and non-discriminatory licensing" royalty fees and other licensing terms on implementers or users of

3344-483: The United Kingdom , the term "back-to-back agreement" refers to an NDA entered into with a third party who legitimately receives confidential information, putting them under similar non-disclosure obligations as the initial party granted the information. Case law in a 2013 Court of Appeal decision ( Dorchester Project Management v BNP Paribas ) confirmed that a confidentiality agreement will be interpreted as

3432-440: The contracted activities are illegal . NDAs are commonly signed when two companies, individuals, or other entities (such as partnerships, societies, etc.) are considering doing business and need to understand the processes used in each other's business for the purpose of evaluating the potential business relationship. NDAs can be "mutual", meaning both parties are restricted in their use of the materials provided, or they can restrict

3520-480: The trademarked compatibility logo. RISC-V has a modular design, consisting of alternative base parts, with added optional extensions. The ISA base and its extensions are developed in a collective effort between industry, the research community and educational institutions. The base specifies instructions (and their encoding), control flow, registers (and their sizes), memory and addressing, logic (i.e., integer) manipulation, and ancillaries. The base alone can implement

3608-611: The "Simplified BSD License" as stated in the IETF Trust Legal Provisions and Copyright FAQ based on RFC 5377. In August 2012, the IETF combined with the W3C and IEEE to launch OpenStand and to publish The Modern Paradigm for Standards. This captures "the effective and efficient standardization processes that have made the Internet and Web the premiere platforms for innovation and borderless commerce". The declaration

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3696-495: The IETF and ITU-T explicitly refer to their standards as "open standards", while the others refer only to producing "standards". The IETF and ITU-T use definitions of "open standard" that allow "reasonable and non-discriminatory" patent licensing fee requirements. There are those in the open-source software community who hold that an "open standard" is only open if it can be freely adopted, implemented and extended. While open standards or architectures are considered non-proprietary in

3784-518: The IETF itself as being "open standards," and lists the standards produced by ANSI , ISO , IEEE , and ITU-T as examples. As the IETF standardization processes and IPR policies have the characteristics listed above by ITU-T, the IETF standards fulfill the ITU-T definition of "open standards." However, the IETF has not adopted a specific definition of "open standard"; both RFC 2026 and the IETF's mission statement (RFC 3935) talks about "open process," but RFC 2026 does not define "open standard" except for

3872-483: The RISC instruction set DLX for the first edition of Computer Architecture: A Quantitative Approach in 1990 of which David Patterson was a co-author, and he later participated in the RISC-V origination. DLX was intended for educational use; academics and hobbyists implemented it using field-programmable gate arrays (FPGA), but it was never truly intended for commercial deployment. ARM CPUs, versions 2 and earlier, had

3960-490: The RISC-V Foundation announced that it would relocate to Switzerland, citing concerns over U.S. trade regulations. As of March 2020, the organization was named RISC-V International, a Swiss nonprofit business association. As of 2019, RISC-V International freely publishes the documents defining RISC-V and permits unrestricted use of the ISA for design of software and hardware. However, only members of RISC-V International can vote to approve changes, and only member organizations use

4048-721: The University of California, Berkeley ( RISC-I and RISC-II published in 1981 by Patterson, who refers to the SOAR architecture from 1984 as "RISC-III" and the SPUR architecture from 1988 as "RISC-IV"). At this stage, students provided initial software, simulations, and CPU designs. The RISC-V authors and their institution originally sourced the ISA documents and several CPU designs under BSD licenses , which allow derivative works—such as RISC-V chip designs—to be either open and free, or closed and proprietary. The ISA specification itself (i.e.,

4136-467: The address as a base register plus offset allows single instructions to access data structures. For example, if the base register points to the top of a stack, single instructions can access a subroutine's local variables in the stack. Likewise the load and store instructions can access a record-style structure or a memory-mapped I/O device. Using the constant zero register as a base address allows single instructions to access memory near address zero. Memory

4224-489: The cost of software by enabling far more reuse. It should also trigger increased competition among hardware providers, who can then devote more resources toward design and less for software support. The designers maintain that new principles are becoming rare in instruction set design, as the most successful designs of the last forty years have grown increasingly similar. Of those that failed, most did so because their sponsoring companies were financially unsuccessful, not because

4312-403: The costs of such a team, commercial vendors of processor intellectual property (IP), such as Arm Ltd. and MIPS Technologies , charge royalties for the use of their designs and patents . They also often require non-disclosure agreements before releasing documents that describe their designs' detailed advantages. In many cases, they never describe the reasons for their design choices. RISC-V

4400-796: The court agreed that the relevant wording "went further than could reasonably be required" to protect commercial information. The agreement was held to be in breach of Article 101 of the Treaty on the Functioning of the European Union , which prohibits agreements which had the object or effect of distorting competition, and was therefore unenforceable. NDAs are very common in the United States, with more than one-third of jobs in America containing an NDA. The United States Congress passed

4488-412: The current ratified Unprivileged ISA Specification. The instruction set base is specified first, coding for RISC-V, the register bit-width, and the variant; e.g., RV64I or RV32E . Then follows letters specifying implemented extensions, in the order of the above table. Each letter may be followed by a major optionally followed by "p" and a minor option number. It defaults to 0 if a minor version number

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4576-649: The degree of openness will be taken into account when selecting an appropriate standard: The UK government 's definition of open standards applies to software interoperability, data and document formats. The criteria for open standards are published in the "Open Standards Principles" policy paper and are as follows. The Cabinet Office in the UK recommends that government departments specify requirements using open standards when undertaking procurement exercises in order to promote interoperability and re-use, and avoid technological lock-in. The Venezuelan Government approved

4664-555: The encoding of the instruction set) was published in 2011 as open source, with all rights reserved. The actual technical report (an expression of the specification) was later placed under a Creative Commons license to permit enhancement by external contributors through the RISC-V Foundation, and later RISC-V International. A full history of RISC-V has been published on the RISC-V International website. Commercial users require an ISA to be stable before they can use it in

4752-595: The endianness of the implementation is hardwired, or may be writable. An execution environment interface may allow accessed memory addresses not to be aligned to their word width, but accesses to aligned addresses may be faster; for example, simple CPUs may implement unaligned accesses with slow software emulation driven from an alignment failure interrupt . Like many RISC instruction sets (and some complex instruction set computer (CISC) instruction sets, such as x86 and IBM System/360 and its successors through z/Architecture ), RISC-V lacks address-modes that write back to

4840-452: The events complained about. Such conditions in an NDA may not be enforceable in law, although they may intimidate the former employee into silence. A similar concept is expressed in the term "non-disparagement agreement", which prevents one party from stating anything ' derogatory ' about the other party. A non-disclosure agreement (NDA) may be classified as unilateral, bilateral, or multilateral: A unilateral NDA (sometimes referred to as

4928-506: The following conditions: The South African Government approved a definition in the "Minimum Interoperability Operating Standards Handbook" (MIOS). For the purposes of the MIOS, a standard shall be considered open if it meets all of these criteria. There are standards which we are obliged to adopt for pragmatic reasons which do not necessarily fully conform to being open in all respects. In such cases, where an open standard does not yet exist,

5016-581: The following criteria: Italy has a general rule for the entire public sector dealing with Open Standards, although concentrating on data formats, in Art. 68 of the Code of the Digital Administration ( Codice dell'Amministrazione Digitale ) [applications must] allow representation of data under different formats, at least one being an open data format. [...] [it is defined] an open data format,

5104-488: The former employee into silence despite this. In some legal cases where the conditions of a confidentiality agreement have been breached, the successful party may choose between damages based on an account of the commercial profits which might have been earned if the agreement had been honoured, or damages based on the price of releasing the other party from its obligations under the agreement. Commercial entities entering into confidentiality agreements need to ensure that

5192-480: The instruction sets were technically poor. Thus, a well-designed open instruction set designed using well-established principles should attract long-term support by many vendors. RISC-V also encourages academic usage. The simplicity of the integer subset permits basic student exercises, and is a simple enough ISA to enable software to control research machines. The variable-length ISA provides room for instruction set extensions for both student exercises and research, and

5280-608: The loads and stores. They set the upper 16 bits by a load upper word instruction. This permits upper-halfword values to be set easily, without shifting bits. However, most use of the upper half-word instruction makes 32-bit constants, like addresses. RISC-V uses a SPARC -like combination of 12-bit offsets and 20-bit set upper instructions. The smaller 12-bit offset helps compact, 32-bit load and store instructions select two of 32 registers yet still have enough bits to support RISC-V's variable-length instruction coding. RISC-V handles 32-bit constants and addresses with instructions that set

5368-712: The loss of R&D knowledge through employee turnover in Indian IT firms". They are often used by companies from other countries who are outsourcing or offshoring work to companies in India. Companies outsourcing research and development of biopharma to India use them, and Indian companies in pharmaceuticals are "competent" in their use. In the space industry , NDAs "are crucial". "Non-disclosure and confidentiality agreements ... are ... generally enforceable as long as they are reasonable." Sometimes NDAs have been anti-competitive and this has led to legal challenges. In

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5456-400: The needs of markets and consumers. This drives innovation which, in turn, contributes to the creation of new markets and the growth and expansion of existing markets. There are five, key OpenStand Principles, as outlined below: 1. Cooperation Respectful cooperation between standards organizations, whereby each respects the autonomy, integrity, processes, and intellectual property rules of

5544-607: The openness of the resulting specification, the openness of the drafting process, and the ownership of rights in the standard. The term "standard" is sometimes restricted to technologies approved by formalized committees that are open to participation by all interested parties and operate on a consensus basis. The definitions of the term open standard used by academics, the European Union , and some of its member governments or parliaments such as Denmark , France , and Spain preclude open standards requiring fees for use, as do

5632-411: The organization that owns the copyright on the specification. As such these specifications are not considered to be fully open . Joel West has argued that "open" standards are not black and white but have many different levels of "openness". A more open standard tends to occur when the knowledge of the technology becomes dispersed enough that competition is increased and others are able to start copying

5720-711: The others. 2. Adherence to Principles – Adherence to the five fundamental principles of standards development, namely 3. Collective Empowerment Commitment by affirming standards organizations and their participants to collective empowerment by striving for standards that: 4. Availability Standards specifications are made accessible to all for implementation and deployment. Affirming standards organizations have defined procedures to develop specifications that can be implemented under fair terms. Given market diversity, fair terms may vary from royalty-free to fair, reasonable, and non-discriminatory terms (FRAND). 5. Voluntary Adoption Standards are voluntarily adopted and success

5808-419: The parties involved to reach a unanimous consensus on a multilateral agreement. A NDA can protect any type of information that is not generally known. They may also contain clauses that will protect the person receiving the information so that if they lawfully obtained the information through other sources they would not be obligated to keep the information secret. In other words, the NDA typically only requires

5896-425: The prefix. They should be specified after all standard extensions, and if multiple non-standard extensions are listed, they should be listed alphabetically. Profiles and platforms for standard ISA choice lists are under discussion. ... This flexibility can be used to highly optimize a specialized design by including only the exact set of ISA features required for an application, but the same flexibility also leads to

5984-647: The purpose of defining what documents IETF standards can link to. RFC 2026 belongs to a set of RFCs collectively known as BCP 9 (Best Common Practice, an IETF policy). RFC 2026 was later updated by BCP 78 and 79 (among others). As of 2011 BCP 78 is RFC 5378 (Rights Contributors Provide to the IETF Trust), and BCP 79 consists of RFC 3979 (Intellectual Property Rights in IETF Technology) and a clarification in RFC 4879. The changes are intended to be compatible with

6072-644: The receiving party to maintain information in confidence when that information has been directly supplied by the disclosing party Some common issues addressed in an NDA include: Deeds of confidentiality and fidelity (also referred to as deeds of confidentiality or confidentiality deeds) are commonly used in Australia . These documents generally serve the same purpose as and contain provisions similar to NDAs used elsewhere. NDAs are used in India . They have been described as "an increasingly popular way of restricting

6160-428: The registers. For example, it does not auto-increment. RISC-V manages memory systems that are shared between CPUs or threads by ensuring a thread of execution always sees its memory operations in the programmed order. But between threads and I/O devices, RISC-V is simplified: it doesn't guarantee the order of memory operations, except by specific instructions, such as fence . A fence instruction guarantees that

6248-571: The results of predecessor operations are visible to successor operations of other threads or I/O devices. fence can guarantee the order of combinations of both memory and memory-mapped I/O operations. E.g. it can separate memory read and write operations, without affecting I/O operations. Or, if a system can operate I/O devices in parallel with memory, fence doesn't force them to wait for each other. One CPU with one thread may decode fence as nop . Some RISC CPUs (such as MIPS , PowerPC , DLX , and Berkeley's RISC-I) place 16 bits of offset in

6336-424: The same way using "S" for prefix. Extensions specific to hypervisor level are named using "H" for prefix. Machine level extensions are prefixed with the three letters "Zxm". Supervisor, hypervisor and machine level instruction set extensions are named after less privileged extensions. RISC-V developers may create their own non-standard instruction set extensions. These follow the "Z" naming convention, but with "X" as

6424-531: The same. The first letter following the "Z" by convention indicates the most closely related alphabetical extension category, IMAFDQLCBJTPVN . Thus the Zam extension for misaligned atomics relates to the "A" standard extension. Unlike single character extensions, Z extensions must be separated by underscores, grouped by category and then alphabetically within each category. For example, Zicsr_Zifencei_Zam . Extensions specific to supervisor privilege level are named in

6512-503: The scope of their agreement does not go beyond what is necessary to protect commercial information. In the case of Jones v Ricoh , heard by the High Court in 2010, Jones brought an action against the photocopier Ricoh for breach of their confidentiality agreement when Ricoh submitted a tender for a contract with a third party. Ricoh sought release from its obligations under the agreement via an application for summary judgment , and

6600-485: The sense that the standard is either unowned or owned by a collective body, it can still be publicly shared and not tightly guarded. The typical example of "open source" that has become a standard is the personal computer originated by IBM and now referred to as Wintel , the combination of the Microsoft operating system and Intel microprocessor. There are three others that are most widely accepted as "open" which include

6688-503: The separated privileged instruction set permits research in operating system support without redesigning compilers. RISC-V's open intellectual property paradigm allows derivative designs to be published, reused, and modified. The term RISC dates from about 1980. Before then, there was some knowledge (see John Cocke ) that simpler computers can be effective, but the design principles were not widely described. Simple, effective computers have always been of academic interest, and resulted in

6776-589: The settlement. Examples of such agreements are The Dolby Trademark Agreement with Dolby Laboratories , the Windows Insider Agreement, and the Halo CFP (Community Feedback Program) with Microsoft . In some cases, employees who are dismissed following their complaints about unacceptable practices ( whistleblowers ), or discrimination against and harassment of themselves, may be paid compensation subject to an NDA forbidding them from disclosing

6864-470: The shorthand, "G". A small 32-bit computer for an embedded system might be RV32EC . A large 64-bit computer might be RV64GC ; i.e., RV64IMAFDCZicsr_Zifencei . With the growth in the number of extensions, the standard now provides for extensions to be named by a single "Z" followed by an alphabetical name and an optional version number. For example, Zifencei names the instruction-fetch extension. Zifencei2 and Zifencei2p0 name version 2.0 of

6952-525: The standard. For example, the rules for standards published by the major internationally recognized standards bodies such as the Internet Engineering Task Force (IETF), International Organization for Standardization (ISO), International Electrotechnical Commission (IEC), and ITU-T permit their standards to contain specifications whose implementation will require payment of patent licensing fees. Among these organizations, only

7040-539: The supervisor extension, S, an RVGC instruction set, which includes one of the RV base instruction sets, the G collection of extensions (which includes "I", meaning that the base is non-embedded), and the C extension, defines all instructions needed to conveniently support a general purpose operating system . To name the combinations of functions that may be implemented, a nomenclature is defined to specify them in Chapter 27 of

7128-702: The technology as they implement it. This occurred with the Wintel architecture as others were able to start imitating the software. Less open standards exist when a particular firm has much power (not ownership) over the standard, which can occur when a firm's platform "wins" in standard setting or the market makes one platform most popular. On August 12, 2012, the Institute of Electrical and Electronics Engineers (IEEE), Internet Society (ISOC), World Wide Web Consortium (W3C), Internet Engineering Task Force (IETF) and Internet Architecture Board (IAB), jointly affirmed

7216-492: The upper 20 bits of a 32-bit register. Load upper immediate lui loads 20 bits into bits 31 through 12. Then a second instruction such as addi can set the bottom 12 bits. Small numbers or addresses can be formed by using the zero register instead of lui . Open standard The terms open and standard have a wide range of meanings associated with their usage. There are a number of definitions of open standards which emphasize different aspects of openness, including

7304-667: The use of Open Standards, and is applicable to sovereign entities, central public administration services (including decentralized services and public institutes), regional public administration services and the public sector. In it, Open Standards are defined thus: a) Its adoption is fruit off an open decision process accessible to all interested parties; b) The specifications document must have been freely published, allowing its copy, distribution and use without restrictions; c) The specifications document cannot cover undocumented actions of processes; d) The applicable intellectual property rights, including patents, have been made available in

7392-408: The use of material by a single party. An employee can be required to sign an NDA or NDA-like agreement with an employer, protecting trade secrets. In fact, some employment agreements include a clause restricting employees' use and dissemination of company-owned confidential information. In legal disputes resolved by settlement , the parties often sign a confidentiality agreement relating to the terms of

7480-516: The user-space ISA and version 1.11 of the privileged ISA are frozen , permitting software and hardware development to proceed. The user-space ISA, now renamed the Unprivileged ISA, was updated, ratified and frozen as version 20191213. An external debug specification is available as a draft, version 0.13.2. CPU design requires design expertise in several specialties: electronic digital logic , compilers , and operating systems . To cover

7568-511: The various terms used in this platform specification. The platform policy also provides the needed detail regarding the scope, coverage, naming, versioning, structure, life cycle and compatibility claims for the platform specification. RISC-V has 32 integer registers (or 16 in the embedded variant), and when the floating-point extension is implemented, an additional 32 floating-point registers. Except for memory access instructions, instructions address only registers . The first integer register

7656-408: Was "to have Debian ready to install and run on systems implementing a variant of the RISC-V ISA." Some RISC-V International members, such as SiFive , Andes Technology , Synopsys , Alibaba's Damo Academy , Raspberry Pi , and Akeana, are offering or have announced commercial systems on a chip (SoCs) that incorporate one or more RISC-V compatible CPU cores. As a RISC architecture, the RISC-V ISA

7744-399: Was begun with a goal to make a practical ISA that was open-sourced, usable academically, and deployable in any hardware or software design without royalties. Also, justifying rationales for each design decision of the project are explained, at least in broad terms. The RISC-V authors are academics who have substantial experience in computer design, and the RISC-V ISA is a direct development from

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