Re: [PATCH] ACPI: processor_idle: Skip dummy wait for processors based on the Zen microarchitecture

On 9/20/22 23:36, K Prateek Nayak wrote:

• /*

• * No delay is needed if we are in guest or on a processor
  

• * based on the Zen microarchitecture.
  

• */
  

• if (boot_cpu_has(X86_FEATURE_HYPERVISOR) || boot_cpu_has(X86_FEATURE_ZEN)) return;

In the end, the delay is because of buggy, circa 2006 chipsets? So, we use a CPU vendor specific check to approximate that the chipset is recent and not affected by the bug? If so, is there no better way to check for a newer chipset than this?

Do X86_FEATURE_ZEN CPUs just have unusually painful inl(acpi_fadt.xpm_tmr_blk.address) implementations? Is that why we noticed all of a sudden?