centos-3.10-i686-fix-pcid-bug17925.patch https://bugs.centos.org/view.php?id=17925 When booting a recent 32-bit i686 kernel on a multi-cpu system with 'pcid' cpu feature, only the boot cpu is correctly initialized. The other cpu's fail to initialize, resulting in a badly running or crashing kernel. The reason is two missing patches present in vanilla upstream kernels: x86/mm: Disable PCID on 32-bit kernels x86/mm/32: Move setup_clear_cpu_cap(X86_FEATURE_PCID) earlier Submitted-by: Jerome Borsboom Applied-by: Akemi Yagi --- a/arch/x86/kernel/cpu/common.c 2020-10-21 10:17:08.000000000 -0700 +++ b/arch/x86/kernel/cpu/common.c 2020-12-09 22:10:47.945329193 -0800 @@ -1131,6 +1131,14 @@ static void __init early_identify_cpu(st this_cpu->c_bsp_init(c); cpu_set_bug_bits(c); + +#ifdef CONFIG_X86_32 + /* + * Regardless of whether PCID is enumerated, the SDM says + * that it can't be enabled in 32-bit mode. + */ + setup_clear_cpu_cap(X86_FEATURE_PCID); +#endif } void __init early_cpu_init(void)