Following [1]Linux 7.1 beginning to phase out i486 CPU support and in turn [2]drivers like those for the old AMD Elan SoCs now being removed , for Linux 7.2 the processor support removal is going further to now include some i586 and i686 class processors.

Following the i486 farewell, TSC-less i586/i686 processors are being removed. Supporting those vintage GPUs without the Time Stamp Counter "TSC" instruction are becoming a burden on Linux kernel developers and thus the support is being removed. TSC-capable Intel Pentium processors and the likes will still be supported with this just being for TSC-less i586/i686 CPUs.

Among the CPUs impacted by this latest change is the AMD K5 as well as various Cyrix processor models. The K5 was AMD's first entirely in-house designed processor that was first introduced in 1996 to counter the Intel Pentium CPU.

[3]This patch removing TSC-less CONFIG_M586 support for Linux was queued into tip/tip.git's "x86/cpu" branch. With this removal patch now part of TIP's x86/cpu branch, it's expected to be submitted for the upcoming Linux 7.2 merge window.

With this removal, TSC support can now be assumed as a boot requirement for modern Linux with CONFIG_X86_TSC in turn going to be made unconditional and then being able to remove the various non-TSC code paths from the x86 code in the Linux kernel.



[1] https://www.phoronix.com/news/Linux-7.1-Begins-Removing-i486

[2] https://www.phoronix.com/news/AMD-Elan-Linux-Driver-Removal

[3] https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?h=x86/cpu&id=dbafa16ec2b6be40055db181c99f2529b20dd951