But Ampere solved this with a patch
While modern x86-compatible processors, thanks to AMD, have reached the mark of 128 cores per CPU, processors based on the Arm architecture have long since crossed this mark, and this has become a problem. As it turns out, the Linux operating system is not yet ready for this.
The question was raised by Ampere, which released its 192-core CPUs on Arm. The problem is that two such processors in one system means 384 cores, and today the 64-bit main Linux Arm kernel build only supports up to 256 cores. To solve this problem, Ampere itself introduced a patch that proposes to increase the Linux kernel limit to 512 cores using the “CPUMASK_OFFSTACK” method. In fact, support can be increased to 8192 cores at once, but the limit of 512 was chosen for the sake of economy, since support for each CPU core adds about 8 KB to the size of the kernel image.
It is reported that without patches, support for more than 256 cores in Linux will not appear until next year, when Linux 6.8 is released.