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Wed, 21 Jan 2026 02:04:07 +0000 Date: Wed, 21 Jan 2026 10:03:56 +0800 From: Chao Gao To: Dave Hansen CC: Dave Hansen , , , Borislav Petkov , "H. 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>>> + __u8 x86_platform_id; /* Intel-only. 3 bits */ >> Tail comments are not preferred. I've seen tglx complain about them a few times. > >Yeah, you're right. It doesn't fit well with the rest of the structure. >I'll fix it. > >> Also, "3 bits" is misleading since x86_platform_id actually stores a bit mask. > >Remember, there are two structures in play here. From the cover letter: > >> Treat the platform ID as a peer of model/family/stepping. Store it >> in 'struct cpuinfo_x86', enable matching on it with with 'struct >> x86_cpu_id', and flesh out the 'old_microcode' list with it. > >This hunk is patching 'cpuinfo_x86' which stores the 3 bits explicitly. Hi Dave, This patch has: c->x86_platform_id = intel_get_platform_id(); but intel_get_platform_id() doesn't return the 3 bits; it returns a single-bit mask (or 0 on old CPUs). +static inline u32 intel_get_platform_id(void) +{ + unsigned int val[2]; + + /* + * This can be called early. Use CPUID directly to + * generate the VFM value for this CPU. + */ + if (intel_cpuid_vfm() < INTEL_PENTIUM_III_DESCHUTES) + return 0; + + /* get processor flags from MSR 0x17 */ + native_rdmsr(MSR_IA32_PLATFORM_ID, val[0], val[1]); + return 1 << ((val[1] >> 18) & 7); +} > >I think you're thinking of the mask in 'x86_cpu_id' which is used for >_matching_ this field in patch 5. > >Could you double check that you're asking about the right structure, >please? I've certainly gotten the two structures mixed up before.