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Date:   Mon, 14 Dec 2020 10:28:19 +0800
From:   Tony W Wang-oc <>
To:     Eric Biggers <>
CC:     <>, <>,
        <>, <>, <>,
        <>, <>, <>,
        <>, <>,
        <>, <>,
        <>, <>,
Subject: Re: [PATCH] crypto: x86/crc32c-intel - Don't match some Zhaoxin CPUs

On 12/12/2020 01:43, Eric Biggers wrote:
> On Fri, Dec 11, 2020 at 07:29:04PM +0800, Tony W Wang-oc wrote:
>> The driver crc32c-intel match CPUs supporting X86_FEATURE_XMM4_2.
>> On platforms with Zhaoxin CPUs supporting this X86 feature, When
>> crc32c-intel and crc32c-generic are both registered, system will
>> use crc32c-intel because its .cra_priority is greater than
>> crc32c-generic. This case expect to use crc32c-generic driver for
>> some Zhaoxin CPUs to get performance gain, So remove these Zhaoxin
>> CPUs support from crc32c-intel.
>> Signed-off-by: Tony W Wang-oc <>
> Does this mean that the performance of the crc32c instruction on those CPUs is
> actually slower than a regular C implementation?  That's very weird.

>From the lmbench3 Create and Delete file test on those chips, I think yes.


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