Messages in this thread | | | From | Junichi Nomura <> | Subject | Re: [tip:x86/urgent] x86/PAT: Fix Xorg regression on CPUs that don't support PAT | Date | Wed, 31 May 2017 09:39:03 +0000 |
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On 05/31/17 02:59, Mikulas Patocka wrote: >>> 2. use the PAT patch and revert the change to the function pat_ap_init >>> - i.e. change it to the original: >>> static void pat_ap_init(u64 pat) >>> { >>> if (!boot_cpu_has(X86_FEATURE_PAT)) { >> >> Joy. > > It is interesting - does it mean that the boot cpu does have PAT and the > secondary CPUs don't?
It seems pat_init() is called twice for boot cpu, from mtrr_bp_pat_init() and generic_set_all(). The 2nd call ends up calling pat_ap_init() and it's before boot_cpu_data is copied to cpu_data[0].
-- Jun'ichi Nomura, NEC Corporation / NEC Solution Innovators, Ltd.
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