RISC-V - Wikipedia

This page or section is a stub. You can help the wiki by accurately risv-v to it. It defines basics and boundaries for a family of implementations.

The specification is published under a Creative Common License and actively developed on github. Hardsare problems, which are addressed by open hardware risc-v 70 of RISC-V are the legal problems with developing real hardware processors, be it for educational, hobbyist or economical purposes of most other architectures and the huge historical baggage of some processor families x The base ISA operates on a little-endian memory system, but non-standard extensions may add support for big-endian or bi-endian.

A hart is defined by its own instruction fetch unit. A processor may contain multiple open hardware risc-v 70at least one. Each hart has an ID associated with it.

In Openn the term Exception refers to an unusual condition at run-time associated with hardwxre instruction in the current hardware thread. A Trap is a synchronous transfer of control to a trap handler and is caused by an exceptional condition within a RISC-V thread.

The trap handlers usually execute in a more privileged environment. An external event that occurs asynchronously to the current thread will cause an Interrupt. When an interrupt occurs, some instruction is selected to experience a trap. The spec defines 4 priviledge modes, of which a open hardware risc-v 70 combination has to be implemented.

The modes are:. RV32I offers 31 general-purpose registers x1-x31 which hold integer values, the x0 register is hardwired to zero, all registers are 32 bits wide. It specifies a number of logical and arithmetic operations and, or, xor, shift left and right, addition and subtractionall of which are available with a source register or an immediate. RV32E reduces the number of general-purpose registers to 15 x1-x15and x0 is still hardwired to constant zero.

RV64I is very similar to its bit counterpart, but offers bit wide registers and can read the CSRs in one operation instead of requiring the programmer to read the upper and lower half separately.

Additionaly, there are some instructions to work with words open hardware risc-v 70 bit instead of double-words.

An extensions can be one of the open hardware risc-v 70 defined ones or a vendor-specific one there is opcode space explicitely reserved for this and can define additional elements, including opcodes and registers.

This extensions defines some kind of secondary address space for Control and Status Registerwhich are used for controlling thins like interrupts, privilege level, hart-local timers and such. These registers can be open hardware risc-v 70 via the CSR instructions.

The RVM Extension adds instructions for multiplying, dividing and computing the remainder of a division. The RVA Extension adds instruction disc-v work atomically with memory, including reserved load and conditional store. Adds additional instructions to work with floating points and also the floating point registers. The different extensions differ in the length precision of the floating point numbers.

Allows bit variants of common instructions with a reduced register set 16 instead of 32 and is intented to increase code density.

It can be freely mixed with bit instructions. For advanced setups multiple privilege modes etc QEMU is probably the way to go. Other simulators existbut the author has not yet tried them The most notable example would probably be the HiFive Unleashed open hardware risc-v 70, which is able to run linux, has lpen cores and is expandable.

The Kendryte K e. Jump to: navigationsearch. Things might and open hardware risc-v 70 change! Look at the official specification for the most up-to-date information.

Personal tools Log in. Namespaces Page Discussion. Views Read View source View history. About This site Joining Editing help Recent changes. This page was last modified open hardware risc-v 70 29 Octoberat This page has been accessed 12, times. Contents 1 Architecture 1.

Mar 01,  · While open source software is taking over the world, a push for open source hardware has been quietly www.- RISC-V foundation has been pushing its open sourced instruction set architecture for chips based on the long-established paradigms for reduced instruction set computing. And one of its most vocal advocates is Calista Redmond, the chief executive of the RISC-V . RISC-V International comprises a large member organization building the first open, collaborative community of software and hardware innovators powering innovation at the edge forward. Through various events and workshops, RISC-V International is changing the way the industry works together and collaborates – creating a new kind of open.

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