Loongson is a Chinese company better known for its MIPS processors, and we often see the company being mentioned in mainline Linux changelogs with regards to updated to Loongson MIPS SoC’s.
But with the MIPS architecture fading away, the company has decided to create its own CPU instruction set architecture (ISA) called LoongArch, short for Loongson Architecture, that is independent of x86, Arm, and even RISC-V architecture.
The reason for the move is that foreign CPU manufacturers use the instruction system as a means to control the ecology, and manufacturers like Loongsoon need to obtain “authorization” to develop compatible CPUs, meaning it’s impossible to develop an independent industrial ecosystem. Loongsoon further illustrates the point by saying “Chinese people can write novels in English, but it is impossible to form Chinese national culture based on English”.
That makes sense considering the trade sanctions regularly imposed by the United States that make it hard to plan ahead, and for instance, caused Huawei to stop making new Kirin processors.
LoongArch includes extensions such as vector instructions, virtualization, and binary translation, with around 2500 instructions. EET China has more details about the “first self-developed ISA” in China. Loongsoon notably designed binary translation tools for MIPS Linux, ARM Android, x86 Linux, and x86 Windows instructions into LoongISA so that existing software can be reused. MIPS Linux to LoongISA performance is same to be the same, but there’s a noticeable performance hit for other architecture/OS combos with for instance, x86 Windows to LoongISA only achieving 70% of the native performance.
All new Loongson CPUs developed since 2020 are said to support the new LoongArch architecture, and one of the first LoongArch processors will be Loongsoon LS3C5000 16-core processor clocked at up to 2.5 GHz, manufactured using a 12nm process, and aiming to compete with AMD and Intel server processors.
Loongson said they’ve made sure LoongArch ISA does not infringe existing patents, and EET China says the company has released a LoongArch infrastructure instruction system manual with basic/limited information, and that a more complete version will be released in the future. I could not find any link to the document, so it may not be public yet.