Loongson () is the name of a family of general-purpose, MIPS architecture-compatible microprocessors, as well as the name of the Chinese fabless company (Loongson Technology) that develops them. The processors are alternately called Godson processors, which are described as its academic name.
History
The Godson processors, based on MIPS architecture, were initially developed at the Institute of Computing Technology (ICT), Chinese Academy of Sciences (CAS). The chief architect was . The development of the first Loongson chip was started in 2001. The aim of the Godson project was to develop "high performance general-purpose microprocessors in China", and to become technologically self-sufficient as part of the Made in China 2025 plan. The development was supported by funding via the 10th and 11th Five-Year Plans.
In 2010 the company was commercialized as a separate entity, and in April 2010 Loongson Technology Corporation Limited was formally established and settled in Zhongguancun, Beijing, China. The company is a public–private partnership between ICT and Beijing-based chip designer BLX IC Design Corporation. BLX itself was a spin-off from ICT, and was founded in 2002 with Jiangsu Zhongyi Group. As Loongson is a fabless designer, STMicroelectronics fabricates and markets the processors.
The South China Morning Post reported that since 2020, Loongson has partnered with UnionTech and Sunway to develop and promote the Debian Linux-based Deepin operating system to reduce Chinese computers dependency on Microsoft Windows.
In 2021, Loongson filed for an initial public offering on the Shanghai Stock Exchange STAR Market. The company was seeking to raise US$500 million. Details from this time suggested Loongson needing annual funding, for the first 10 years of its existence, and the company only broke even in 2015.
U.S. sanctions
In March 2023, the United States Department of Commerce added Loongson to the Bureau of Industry and Security's Entity List for acquisition of American technology to support the People's Liberation Army (PLA).
Instruction set architectures
MIPS
Loongson began by using the MIPS64 instruction set architecture (ISA). The internal microarchitecture was independently developed by ICT. Early implementations of the family lacked four instructions patented by MIPS Technologies (US4814976A, unaligned load-store) to avoid legal issues.
In 2007, a deal was reached by MIPS Technologies and ICT. STMicroelectronics bought a MIPS license for Loongson, and thus the processor can be promoted as MIPS-based or MIPS-compatible instead of MIPS-like.
In June 2009, ICT licensed the MIPS32 and MIPS64 architectures directly from MIPS Technologies.
In August 2011, Loongson Technology Corp. Ltd. licensed the MIPS32 and MIPS64 architectures from MIPS Technologies, Inc. for continued development of MIPS-based Loongson CPU cores.
LoongISA
The Loongson 3A2000 in 2015 saw the adoption of 1.0, an expanded instruction set that is a superset of MIPS64 release 2. It can be broken down into:
LoongEXT, general-purpose extensions, 148 instructions
LoongVZ, virtualisation extensions to the "VZ" system introduced in MIPS64 release 5, 5 instructions LoongBT, faster x86 and ARM binary translation, 213 instructions LoongSIMD, formerly LoongMMI (in Loongson 2E/F), for 128-bit SIMD, 1014 instructions MIPS SIMD Architecture (MSA), DSP, and VZ modules from MIPS Release 5
The LoongISA instructions were introduced as part of the GS464E cores. The binary translation instructions have the specific benefit of speeding up Intel x86 CPU emulation at a cost of 5% of the total die area. The new instructions help a QEMU hypervisor translate instructions from x86 to MIPS with only a reported 30% performance penalty.
LoongArch
Loongson moved to their own processor instruction set architecture (ISA) in 2021 with the release of the Loongson 3 5000 series. A Loongson developer described it as "...a new RISC ISA, which is a bit like MIPS or RISC-V. LoongArch includes a reduced 32-bit version (LA32R), a standard 32-bit version (LA32S) and a 64-bit version (LA64)". The stated rationale was to make Loongson and China not dependent on foreign technology or authorisation to develop their processor capability, whilst not infringing on any technology patents.
The ISA has been referred to as "a fork of MIPS64r6" due to a perceived lack of changes judging from instruction listings.