Messages in this thread | | | Subject | Re: [PATCH v1 2/3] x86/cpu: Set low performance CRC32C flag on some Zhaoxin CPUs | From | Dave Hansen <> | Date | Thu, 7 Jan 2021 07:52:49 -0800 |
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On 1/6/21 10:19 PM, Tony W Wang-oc wrote: > + /* > + * These CPUs declare support SSE4.2 instruction sets but > + * having low performance CRC32C instruction implementation. > + */ > + if (c->x86 == 0x6 || (c->x86 == 0x7 && c->x86_model <= 0x3b)) > + set_cpu_cap(c, X86_FEATURE_CRC32C); > }
On the Intel side, we've tried to move away from open-coded model numbers. Say another CPU is released that has a microarchitecture close to 0x3b, but has a model of 0x3c. It's a *LOT* easier to grep for INTEL_FAM6_NEHALEM (or whatever) than 0x3c. See:
arch/x86/include/asm/intel-family.h
for examples.
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