C-SKY CPU Architecture For Linux 5.6 Picks Up Stack Protector, PCI Support

While two weeks past the Linux 5.6 merge window some late changes for the C-SKY CPU architecture were accepted today.

C-SKY's Guo Ren accidentally missed the recent Linux 5.6 merge window but Linus Torvalds was fine with pulling in these late changes that include both fixes and features.

C-SKY is the Chinese 32-bit CPU architecture added for Linux 4.20. C-SKY is a Chinese domestic 32-bit CPU intended for low-power SoCs and deployed for consumer electronic devices from printers and cameras to DVRs. C-SKY is a member of the RISC-V Foundation but this C-SKY architecture within the Linux kernel is a custom CPU architecture.

Performance isn't a major focus for C-SKY and we're unlikely to see these processors make it into any PCs, but the Linux support is there given the number of consumer devices running Linux-based platforms. Along with the Linux kernel support has been GCC compiler toolchain support and related open-source enablement.

It's been a few kernel cycles since last seeing any real patches for C-SKY but these late changes for Linux 5.6 do bring a few features on top of bug fixing.

There is PCI support now for C-SKY though it appears to be primarily intended for virtual environments in supporting the likes of QEMU's virt-pci-9pfs driver. Also new is initial stack protector support in order to report kernel stack corruption in conjunction with the GCC compiler support. Rounding out the feature work is Tightly-Coupled Memory (TCP) / SRAM support on the C-SKY SoC bus.

C-SKY fixes for Linux 5.6 include fixing the cache flushing code, addressing SMP boot problems, Kconfig updates, copy_thread_tls support, and other general code fixes.

The C-SKY changes were merged today ahead of the expected Linux 5.6-rc3 release in a few hours.