C-SKY is a RISC-based 32-bit architecture developed by C-SKY Microsystems, a subsidiary of Alibaba Group's T-Head semiconductor division. The instruction set was derived by the M·CORE.
History C-SKY Microsystems was founded in Hangzhou, China, in 2001. The architecture was developed to provide a domestic Chinese alternative to ARM and MIPS for embedded applications.
In April 2018, Alibaba Group acquired C-SKY Microsystems to bolster its chip-making capabilities. Following the acquisition, the company was integrated into Alibaba's "T-Head" (Pingtouge) semiconductor arm.
While T-Head has since pivoted heavily toward RISC-V (with the XuanTie series), C-SKY remains a supported legacy architecture with millions of units in the field.
Architecture The C-SKY ISA is designed for high code density and low power consumption. It features two primary versions:
V1: The legacy version, focused on basic embedded control. V2: The modern version, which introduced a 16/32-bit mixed-length instruction set (similar to ARM’s Thumb-2). This version supports hardware floating-point units (FPU), DSP extensions, and multi-core configurations.
Common CPU Cores:
CK801 / CK802: Ultra-low power, 2-stage pipeline. CK803: Low power with optional FPU and DSP extensions. CK810: High-performance application processor with a 10-stage pipeline and MMU support for Linux. CK860: High-end multi-core variant with SMP support.
Software Support Linux Kernel: Support was officially merged in Kernel 4.20 (late 2018). GCC: Official support was added in GCC 9 (2019), allowing for cross-compilation of C/C++ applications. Glibc: The GNU C Library added C-SKY support in version 2.29. Operating Systems: In addition to Linux, it is supported by various RTOS like AliOS Things and Zephyr.
See also Alibaba Group RISC-V Loongson (Another Chinese ISA)
References